ESE's works engine tuner

[Farmaken]

Thank you Frits, my engine was piston port/reed induction ( suzuki ) now converted to full crankcase reed - I guess there could be some degree of all three conditions contributing to the current situation ??

It does seem to get worse as the engine gets hotter through the course of a race

[TZ350]

Don't you weigh more than your rig?

I think I weigh about the same as my rig and I am hoping to weigh 135% of my new rig.

[TZ350]

Hey guys, tz i have been away for a bot how are you going with that cvt setup. Happy to help you where I can. Do you still want to get hold of some cases

Hi Wax

277120

I purchased some new GY6 125/150 CVT parts, because they are pretty cheap here and there are after market parts available for them. The parts come in plain brown box's without any of the naughty words that would define them as illegal for Moto4 (Bucket) racing.

I need an old crank half and reduction box input shaft for their splines. I plan on extending the shafts so they can be run in carrier brgs mounted in the engine plates.

As best as I can figure out the CVT has a range of 3.25:1 to 0.8:1 which is pretty much the same as the GP gear box. So all I would need is a 3:1 primary or final gear reduction ratio.

So the plan is to have on the right hand side of the engine, a 3:1 straight cut reduction gear set to a cross shaft to the front CVT sheave mounted on the left side (keeps the rotation direction correct that way).

And the front chain sprocket behind the rear CVT sheave. That should put the front chain sprocket in the right place relative to the swing arm. The front reduction gear set could be lubed between races with a squirt of chain grease, life expectance does not have to be great.

If you can find an old crank half and reduction box input shaft for a GY6 125-150 I would be very greatful.

[husaberg]

Can you define 'competition part'? I guess anyone can put it on his street bike and go shopping... But yes, it is primarily meant to win races. So what is decisive? The text on the box?


I can (The MNZ can't you grammar so it doesn't matter LOL)
but It maters not its a bit iffy for me even if it as inside the rules (which by the wording, oh bugger this other people can argue it )
I are going a different path anyway.

Did you happen to see my question about the disk vale RSW VS RSA

it probably got lost amongst the hundred others i annoy you with (sorry)




I had a look through the RSA125 and RSW125 manuals i was surprised to see the RSA has a much larger o ring on the disk valve cover.120 vs 126mm
Does this mean that the Rotary valve on the RSA is 4-6mm larger in diameter than the RSW or just the o-ring is out further?
I always assumed they were the same size?
<img src="http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=275751&d=1357450068" width="540px"/>

[twotempi]

I have found a $40 solution to your power to weight problem. Can post details if anyone interested.

[TZ350]

I have found a $40 solution to your power to weight problem. Can post details if anyone interested.

Ok Ill bite ..... but it had better not involve diet and exercise .... :laugh:

[Frits Overmars]

Did you happen to see my question about the disk vale RSW VS RSAI did. But I did not answer it simply because I don't know it off the top of my head. I haven't been in Holland for some time but my archive still is...

[husaberg]

Hi Wax

277120

I purchased some new GY6 125/150 CVT parts, because they are pretty cheap here and there are after market parts available for them. The parts come in plain brown box's without any of the naughty words that would define them as illegal for Moto4 (Bucket) racing.

I need an old crank half and reduction box input shaft for their splines. I plan on extending the shafts so they can be run in carrier brgs mounted in the engine plates.


If you can find an old crank half and reduction box input shaft for a GY6 125-150 I would be very greatful.
http://www.ncy-motor.com.tw/product3.php?lang=en&car=&car2=&car3=&search=&page=13
I doubt i came apon the right page (in this link)but pretty sure the shaft you want was there...no crankhalf but i guss Newmanz and co if you can't find SH

I did. But I did not answer it simply because I don't know it off the top of my head. I haven't been in Holland for some time but my archive still is...

Thanks Frits does it sound plausible that the RSA could be bigger (I won't hold you too it you are most patient with me already)
I am not sure you have mentioned where you currently are working? if thats not to intrusive

[wax]

I will see what I can find for you

[TZ350]

Thanks ...

[TZ350]

http://www.ncy-motor.com.tw/product3.php?lang=en&car=&car2=&car3=&search=&page=13 I doubt i came apon the right page (in this link)but pretty sure the shaft you want was there...

Thanks Husa I remember it now, $8 USD each from memory.

[Frits Overmars]

Thanks Frits does it sound plausible that the RSA could be bigger (I won't hold you too it you are most patient with me already). I am not sure you have mentioned where you currently are working? if thats not to intrusivePlausible, yes.
I am working in Beer Country aka Germany and constantly on the phone with Chianti Country. Life is a beach bitch...

[koba]

Chianti

I had to google that.

At least you are in the country with the better beverage.

[husaberg]

I had to google that.

At least you are in the country with the better beverage.

Yeah but its too cold to drink the beer at the moment over there..............:cold:

[koba]

too cold to drink the beer

No such thing! :drinknsin

[TZ350]

277135

Ok ... this and a spare MC16 frame from Husa is the start of my new "Less is More" project, "Less weight" and "More power", for a better, smarter, power to weight project.

[Henk]

Get that Cotswald geezer off the beer and pies, easy 10kg there.

[chrisc]

Tim, the Aprilia looked like it went very well today!

http://christophercain.cc/b/d/mtwelljan13/IMG_1941.jpg

[koba]

277135

Ok ... this and a spare MC16 frame from Husa is the start of my new "Less is More" project, "Less weight" and "More power", a better, smarter, power to weight project.

Some random thoughts that spring to mind from my experience with my MC18 (Similar).

Running one front brake disk was a more noticeable improvement than I would have thought.

The arse will need to be jacked up, a lot.

It's really hard to get the weight bias as far forward as required, husa and I had independently concluded that chopping it down (shortening) would be a desirable course of action.

An R6 shock may work (Farmaken has since tried than and it's looking good for him!)

Dave once showed me all the cutting I could do to lighten the frame without loosing strength/rigidity for my application, there was a lot that could come off.

XXXX XX X XXXX XXXXXXXXXX XXXX XXXXXXX XXXXX XXX XXXX XXX XXXX XXXX XXX X XXXXXXX XXXXXXX XX XXXXXXXXX XXXXXXXX XXX XXXX XXXXXX XXXX X XXXXX XX XX XXXXXXXXXXXX XXXX XXXXX XX XXXXXXXXX XXX XX XXXXXXX.

(Sorry about the X's, I want to try that before I open my mouth)

RS250 forks and other parts of the same vintage are really similar on the outside and would be great but good luck finding some for a good price!

The top mounting of the rear shock is inconvenient to change compared to say, an RGV250.

The forks are OK for what they are but are faeces compared to proper cartridge units, I think even the later NSR's may have been damper rods when RGV's and TZR's had USD Cartrige goodness.

It's really roomy for engine mounting, put it as far forward as you can with the chain still working.

Do everything else you can to keep weight forward, including riding position.

[TZ350]

Thanks for the tips, I may need to ask questions as I go along.

[rgvbaz]

Tim, the Aprilia looked like it went very well today!

http://christophercain.cc/b/d/mtwelljan13/IMG_1941.jpg

Looks nice. I love the handling on these little RS50's... Great fun!

[jasonu]

277135

Ok ... this and a spare MC16 frame from Husa is the start of my new "Less is More" project, "Less weight" and "More power", a better, smarter, power to weight project.

You can save a good 2kg by replaceing the gas tank with a fiberglass top shell with an alloy cell foamed inside. Kel has the one I made, ask him to weigh it and compare it to your NSR tank.

[cotswold]

Get that Cotswald geezer off the beer and pies, easy 10kg there.

I think you will find he is only the interim rider and at 74kg is only 2 more than rick, so leave my pies alone..............

[TZ350]

You can save a good 2kg by replaceing the gas tank with a fiberglass top shell with an alloy cell foamed inside. Kel has the one I made, ask him to weigh it and compare it to your NSR tank.

I have had a good look at that tank and it is very light, I don't have an NSR tank but I do have a FZR one, I will weigh those when I get back.

[kel]

You can save a good 2kg by replaceing the gas tank with a fiberglass top shell with an alloy cell foamed inside. Kel has the one I made, ask him to weigh it and compare it to your NSR tank.
Um not exactly, although TZ will be able to weigh it.
TZ seems to be playing coy about the plans for the NSR frame. I've been helping out with supplying/sourcing parts, I shouldn't say too much but its fair to say it will be very light and very trick :innocent:

[TZ350]

<iframe width="560" height="315" src="http://www.youtube.com/embed/LU-ynRoqDEs" frameborder="0" allowfullscreen></iframe>

Irish Road Racing .... :facepalm:

[wobbly]

Been away racing for a few days and it takes a couple of hours to catch up on the thread, dont you guys have anything better to do.
Saw the comment about so called "trick " spark plugs - calling a BR9EIX a trick plug is like calling a Corolla a trick car compared to a split screen Morris Minor..
The Iridium plugs are useless in the respect of making more power over a bog standard BR9EGV say at 1/4 the price.
And be aware that the instant you get deto, the iridium ceramic will split and drop off.
The R7376 type plug is identical to the special shorty plugs as used on RS125/250 etc except it has a normal body size.
They have iridium fine wire centre electrode, a laser welded fine wire platinum earth strap, and a heaver duty ceramic.
These ARE trick plugs, and show a result on a dyno when pushing the outer limits of 2T tuning.
Unless you are hard out tuning to death - you get jack shit for your money.

I have posted these tests here before - 4 different plugs back to back - 3 runs each test averaged, now tell me plugs make no difference.

[TZ350]

Saw the comment about so called "trick " spark plugs - calling a BR9EIX a trick plug is like calling a Corolla a trick car compared to a split screen Morris Minor.

I think the "Trick" was the bike shop reliving Tim of $29 ??? ....


be aware that the instant you get deto, the (BR9EIX) iridium ceramic will split and drop off.

The R7376 type plug is identical to the special shorty plugs as used on RS125/250 etc except it has a normal body size.

They have iridium fine wire centre electrode, a laser welded fine wire platinum earth strap, and a heaver duty ceramic.

Wob ... will deto cause the same problem with the R7376 too? am I better of using gold pladium and/or std electrode plugs untill I have the over rev deto thing sorted.

[F5 Dave]

I saw a Morris last week morphed into a small scale Monster truck. I didn't have a camera, but it was a laugh.

From my testing of plugs, you have to test what suits your engine & again if you radically alter it. I've had std plugs work as well as EGVs, but I've also seen 1/2 hp increases on a 50 with EGVs as the com was high enough.

I've seen a full hp increase on a friend's 50 with an NGK racing plug (maybe a R7376, can't remember), but same plug on my bike nada, despite 19:1 com ratio (that was an accident, but worked at the time). His chamber was super shallow & shrouded the std plug so a welded side strap helped.

[cotswold]

I was trying to get to this weekends fun day in Auckland with my 1/2 finished GP but could not get it running right, I have put a video on youtube as the file is from an Ipad and I also cant make that work for this forum.

http://youtu.be/eaHpanau3Yw

It starts, idles and revs with the choke open, when the choke is off it backfires and dies, I am on 125 main and the needle on the top clip, I ran out of jets at 125 but am I right in thinking it's still too lean?

Kx100 ignition set by the suck it and see method

[Frits Overmars]

... I am on 125 main and the needle on the top clip, I ran out of jets at 125 but am I right in thinking it's still too lean?A bit more information couldn't hurt. There are numbers on needles and needle jets, you know...
But checking if the main jet is too small is easy: leave it out. If things improve, it was too small.

[TZ350]

Kx100 ignition set by the suck it and see method

277210

KX 80/100 ignitions like this one have timing marks that line up with a pointer cast into the GP engine case for 20 deg BTDC. Which is a pretty handy place to start with. The ESE bikes running KX ignitions all had final settings somewhere in the range of +-5deg from there, my engine with a squish band liked 16, others with the original open chamber, 20 or 25.

[cotswold]

A bit more information couldn't hurt. There are numbers on needles and needle jets, You know...
But checking if the main jet is still too small is easy: leave it out. If things improve, it was too small.

Thanks Frits,

The main is a 125
The pilot is a 40
the needle is 4 ej14

I removed the main and the bike will start and tick over but will not rev

[cotswold]

277210

KX 80/100 ignitions like this one have timing marks that line up with a pointer cast into the GP engine case for 20 deg BTDC. Which is a pretty handy place to start from and the final setting will be +-5deg from there.

Thanks Rob,

I was thinking it was a carb issue due to it revving freely with the choke on but back firing with the choke off, I was sort of hoping someone could point me in the right direction as I will need to order some more jets. I have from 97.5 up to 125, not all of them are original and after our experience with the pattern parts I would be looking at original part jets.

[speedpro]

It runs with the choke on but fluffs about with the choke off - reasonably obvious to me. I'd put the needle clip in the middle just as a place to start and start with BIG jets and work down until it runs. Rob should be able to tell you what is a big jet for your engine. Testing with no main jet fitted at all is good but only confirms that the needle jet is not a restriction to fuel flow. I've drilled jets out to see what happens and soldered them back up and redrilled them. It's a good way of getting in the ballpark without buying a box of jets most of which you don't need after you've tuned it. I then buy a small range of the correct size jets once I know what is needed. Plus the last dyno session nobody had jets big enough and the actual size was a surprise, to me anyway.

[cotswold]

It runs with the choke on but fluffs about with the choke off - reasonably obvious to me. I'd put the needle clip in the middle just as a place to start and start with BIG jets and work down until it runs. Rob should be able to tell you what is a big jet for your engine. Testing with no main jet fitted at all is good but only confirms that the needle jet is not a restriction to fuel flow. I've drilled jets out to see what happens and soldered them back up and redrilled them. It's a good way of getting in the ballpark without buying a box of jets most of which you don't need after you've tuned it. I then buy a small range of the correct size jets once I know what is needed. Plus the last dyno session nobody had jets big enough and the actual size was a surprise, to me anyway.

Thanks Mike,

I have played with the clip position and it made no difference but the idea of drilling out one of the pattern jets sounds like a plan......

[TZ350]

If its a Mikuni round head main jet 125 sounds bigish, but a Kehien 125 would be to small, drills and spare jets at work, pop around tomorrow and borrow them, quickest way to find what you need.

[cotswold]

125 sounds big, drill and spare jets at work, pop around and borrow them, quickest way to find what you need.

You are right, I drilled one of the TM jets and it was like having no main, so put the clip down 2 and put in a proper 100 main and it is much better, it still pops if I hold it half open but revs freely on the stand, I'll take it to work tomorrow and try it up the road.
I am saving for an ignitech so may just flick off the kx one and wait.

[F5 Dave]

I think the "Trick" was the bike shop reliving Tim of $29 ??? ....



Wob ... will deto cause the same problem with the R7376 too? am I better of using gold pladium and/or std electrode plugs untill I have the over rev deto thing sorted.

Sweet $207 ea (R7376 at bottom of page)
http://www.bits4bikes.co.nz/accessories/engine/1667.aspx

or I've just now bought a couple off Amazon for $45ea landed. My they do vary in price somewhat.

[wobbly]

The old BR10EGV isnt prone to ceramic cracking at all, and the 7376 at 4 times the price of those is virtually indestructible.
I get the plugs off Amazon as well when a good deal comes up occasionally - best i have done was 52nzd landed.
One retailer i saw wanted 300nzd for the genuine shorty NGK plug cap for RS125, that is why I went searching and contacted NGK in USA who told me about the
exact same configuration plug with a normal body shape.

[cotswold]

Sweet $207 ea (R7376 at bottom of page)
http://www.bits4bikes.co.nz/accessories/engine/1667.aspx

or I've just now bought a couple off Amazon for $45ea landed. My they do vary in price somewhat.

http://www.ebay.com/itm/NGK-R7376-10-4457-4p-Racing-Spark-for-RS125-87-97-KX125-04-TZ125-94-99-ROTAX-130-/300384577275?pt=Motorcycles_Parts_Accessories&hash=item45f050e6fb&vxp=mtr

[TZ350]

The old BR10EGV isnt prone to ceramic cracking at all, and the 7376 at 4 times the price of those is virtually indestructible.

Thanks ...

[F5 Dave]

http://www.ebay.com/itm/NGK-R7376-10-4457-4p-Racing-Spark-for-RS125-87-97-KX125-04-TZ125-94-99-ROTAX-130-/300384577275?pt=Motorcycles_Parts_Accessories&hash=item45f050e6fb&vxp=mtr

yes I saw those. $47ea landed + I didn't want to spring for 4 just at the moment. Much better shipping rate than the $18 I paid. But end cost is similar.

[chrisc]

Another of Tim (Fixer) but this time on the RS GP125 bike during the 'borrowed bike race' on Sunday.

http://christophercain.cc/b/d/mtwelljan13/2585.jpg

And Cully's FZR GP (not the beast which looks very similar). The exhaust looked like it was getting very close to the ground at times! Was it rubbing the floor?

http://christophercain.cc/b/d/mtwelljan13/2399.jpg

[bucketracer]

Another of Tim (Fixer) but this time on the RS GP125 bike during the 'borrowed bike race' on Sunday.

I heard he came second in the first leg of the borrowed bike race and lead the second for most of the race to take the win.

[chrisc]

I heard he came second in the first leg of the borrowed bike race and lead the second for most of the race to take the win.

I couldn't comment because he was far ahead of me and I didn't see the result but that doesn't sound incorrect at all

[bucketracer]

TeeZee has the result sheets, hopefully when he gets back to work tomorrow he can get them scanned and posted up.

[TZ350]

Mt Wellington Fun Day Results.

There are a few anomalies, like the races run anti clockwise had to do a lap before triggering the timer and I have forgotten which races ran the oval and which included the infield, it was a fun day and I wasn't paying to much attention. Maybe someone else can fill us in.

277497

And another :first: for the Team ESE bike prepared by Chambers and Thomas and piloted by Tim F, (Round 2 of the Borrowed Bike race).

[fixer]

Tim, the Aprilia looked like it went very well today!

http://christophercain.cc/b/d/mtwelljan13/IMG_1941.jpg


Thanks for that pic Chris ... yeah, I had a ball! 8hp is all you really need to have fun. That said, I don't think Renee's 13mm carb is going to be attached to her for much longer. (Yes, she is an Italian bike with a French name - apologies to anyone who is offended).

I also had the chance to ride Avalon's bike at the weekend thanks to team ESE (RS125 chassis with ESE GP125 motor). I have to admit that it was an adrenalin-filled few laps. There's no doubt that it's got a strong engine, little weight, handles well and brakes like you've hit a brick wall, but it's a certainly a challenge to ride on a tight track. The power really comes on strong through the esses. And it was so fast on the straight bits, that I was constantly in danger of running into the back of slower riders.

I think that with a decent amount of practice, a good (and fit) rider would be very hard to beat riding that bike. An average rider would struggle to come to grips with it. I take my hat off to Avalon - she's clearly a very good rider.

Tim

[fixer]

Mt Wellington Fun Day Results.

There are a few anomalies, like the races run anti clockwise had to do a lap before triggering the timer and I have forgotten which races ran the oval and which included the infield, it was a fun day and I wasn't paying to much attention. Maybe someone else can fill us in.

277497

And another :first: for the Team ESE bike prepared by Chambers and Thomas and piloted by Tim F, (Round 2 of the Borrowed Bike race).


Each of the 3 fields (F4 A-grade, F4 B-grade, F4 C-grade plus F5) got 4 races:
Race 1 - full track anticlockwise
Race 2 - full track clockwise
Race 3 - oval track anticlockwise
Race 4 - oval track clockwise

Plus at the end we had the two all-in "borrowed bike races":
Race 1 - oval track anticlockwise
Race 2 - oval track clockwise

My thanks again to team ESE for the use of their little rocket. If I had more time to get used to the riding position, the race pattern shift and to figure out how far you can actually lean an RS125 chassis over, I would have gone a bit faster. :-)

Tim

[fixer]

By the way ... my apologies for the rather dodgy-looking differences in laptimes later in the day in the results that show each rider's individual laptimes (eg 4 hours). Not sure quite what happened there, but the race results and actual laptimes should be ok.
I think a couple of the full-track races were actually 4 laps rather than 5 laps, but hey ... we all had fun.

Though I must apologise to Max Olsen for rather vigorously removing my Aprilia from his bike after Rick, Max and I all fell down in a heap in the esses. This action may have further damaged his tailpiece. My enthusiasm to get back in the race might have got the better of me. I'm happy to donate a large roll of duct tape if it will help!

Tim

[husaberg]

The Rotax cylinder only has a single blade. The Aprilias have a two-stage powervalve system: first only the lower blade opens; then it takes the upper blade with it.
The drawing above left is from the RSA manual; the drawing above right is from the RSW manual. In typical Italian fashion the numbering of the parts differs between the two drawings.

RSW (right): When the shaft 7 turns, the lower blade 14 is lifted by the arm 2. When the lower blade hits the upper blade 13, both blades are lifted further together.

RSA (left): When the shaft 14 turns, the lower blade (not numbered) is lifted by the arm 15. When the lower blade hits the upper blade (also not numbered), both blades are lifted further together.

All other parts are to do with spring-loading the blades, converting the cable movement into turning of the shaft and fixing the cables to the cylinder.
In the 250 cc twins the shafts are coupled by push-pull rods which in turn are cable-operated. The 125 cc singles ared directly cable-operated. The picture shows the RSA's cables.


The idea behind the two stage blade is that with a single PV, as it is retracted it pulls away from the piston.
At 1/2 sroke it is virtually useless due to excessive leakage.
With the two stage as the lower blade retracts, the upper blade is still close to the piston.
At 1/2 stroke the lower blade is sitting flush with the uppers bottom edge.
They then both retract up flush with the roof.
This gives a sealed blade when down at say 100* atdc, and it is still sealed against the piston at 1/2 stroke, say 90* atdc.
This is why the Aprilia PV still works effectively, such that the blades are not fully up at the 80* atdc point till around 12,000rpm.
Exactly the same system in the RZ400, and that PV isnt fully up till 10500, in an engine that peaks at 11500.
The Honda dropping gate or the Yamaha rotary spool valve overcome this by keeping the seal face close to the piston throughout the entire stroke.

I found this today. I missed it earlier (its was in a link elsewhere)
this is a neat little manual.
Both the pictures and words are in English:laugh:
Interestingly the last of the RM250 the X model had a very similar looking valve set up.
http://i.ebayimg.com/t/1997-Suzuki-RM250-power-exhaust-valve-valves-components-parts-97-RM-250-/00/s/NzY4WDEwMjQ=/$(KGrHqZHJDUE63ZSDFoTBPsl)U,2iw~~60_35.JPGhttp://i.ebayimg.com/t/1997-Suzuki-RM250-power-exhaust-valve-valves-components-parts-97-RM-250-/00/s/NzY4WDEwMjQ=/$(KGrHqJHJB!E-EtEG7n)BPsl),J7Hg~~60_35.JPGhttp://i.ebayimg.com/t/1997-Suzuki-RM250-power-exhaust-valve-valves-components-parts-97-RM-250-/00/s/NzY4WDEwMjQ=/$(KGrHqVHJFQE-lFzmvGUBPsl)(T!G!~~60_35.JPG

[bucketracer]

277497

And another :first: for the Team ESE bike prepared by Chambers and Thomas.

Whats that make it, 11th ''A '' grade win this season.


I would be impressed with ESE winning.

There you are SS, its your opportunity to say something sincere and congratulatory.

[Moooools]

Though I must apologise to Max Olsen for rather vigorously removing my Aprilia from his bike after Rick, Max and I all fell down in a heap in the esses. This action may have further damaged his tailpiece. My enthusiasm to get back in the race might have got the better of me. I'm happy to donate a large roll of duct tape if it will help!

Tim

Haha it is not a problem. That's just how racing goes sometimes. I have two new tail pieces on the way so I will have a spare lined up for next time. Although I would love to stay on 2 wheels for a bit longer next race. And beat you. Definitely Beat you. I am a bit worried about you getting more power though. Certainly a bit disappointing to not be able to finish those races off. I think the warm up laps are pretty important on the 50s where they don't get as much heat as quickly. And not having them left us a bit cold for those first corners. Especially on the colder (right) side of the tyre. Something to keep in mind for the organisers I guess.

[chrisc]

http://www.youtube.com/watch?v=OKqLZjYTQIE

[chrisc]

Sigh. I can't sleep.

Here you go guys, a Suzuki GP125 and GP125U service manual... all 136 pages of it. Thanks to Rob for the manual and may it serve to help many in their journey towards 2 stroke euphoria :drinkup:

Be patient, it's a large file (for those who still use windows 98) at 18.0 MB

Suzuki GP125 Service Manual (http://christophercain.cc/b/suzuki-gp125.pdf)

[Perra.S]

Hi everyone, my name is Per-Erik Sandblom, I'm from Sweden and I'm 22 years old and I got this PM from TZ350


50cc dragster
Hi, we would love to see some photos of your 50cc dragster and other small bike dragsters.

So, a year ago I built a turbocharged 50cc. At that time I didn't know as much as I do know so the project flopped. Well, it revved to over 18.000 rpm but it didn't produce any power to speak of. (And now after finding this forum and pit-lane and all the info posted from Jan, Frits, wobbly and everyone else I have understand the reason why it didn't and also learned a lot lot more of twostrokes.. Big Thanks to you all!) I also used a too big turbo, a garret gt15, and after doing some research now I think a MHI td02 or td015 would have been a much better choice.
http://i1210.photobucket.com/albums/cc401/Perra-S/_DSC2467-1.jpg

A new frame was built thus the old one from the turbotesting was really useless
http://i1210.photobucket.com/albums/cc401/Perra-S/_DSC2812.jpg

I then started to playing with n/a engines and building/testing different exhausts of my own design, in the end of the summer I had made around ~10 different. The exhaust nearest to the camera turned out to be the best and produced more power then a very respected exhaustbuilding company here in Europe. It produced 360hp/liter (50cc cylinder) with a smal 21mm carburettor and I'm feeling pretty confident it would have produced even more with a bigger carb.
http://i1210.photobucket.com/albums/cc401/Perra-S/_DSC2806.jpg

Then there was some testing with methanol/nitromethane. I had some problems with the fuel not atomizing correctly so if I ever is going to try it again it would be with EFI.

60%methanol, 35%nitromethane, 5%oil

http://youtu.be/FrP45G9KU30


90%nitromethane, 5%acetone, 5%oil (Im just testing on gravel outside the garage so therefore the backwheel spinns the whole way, didn't got the chance to test it on asphalt because a too weak cylinderstud snapped and caused some damage)

http://youtu.be/NplgLRY84gs


So, I'm not sure if any of this is interesting for you but I posted it on request so I hope someone will enjoy reading it :)


By the way, Regarding Frits talking about rear pulleys with axial slots http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130482536#post1130482536

There is some pulleys were there is room to machine in you're own slots. Like this one from a Yamaha Aerox, and because it's a std. part you're allowed to use it right?
http://mopshop.de/shop/product_info.php?cPath=1_327_1585_5_17805&osCsid=tgi229mb1ggs5g91mir0trpv33&osCsid=tgi229mb1ggs5g91mir0trpv33

Thus it's a std. parts and may not be any suitable in racing, just a tip though.

[Frits Overmars]

Hey Per-Erik, seeing your practice roads makes me jealous. I've looked it up:
Sweden: . . . .20 inhabitants per km².
Netherlands: 448 inhabitants per km². It's a wonder we can even breathe :( .
(By the way: the number for New Zealand is 16. Lucky devils).

PS: Perra, did you try pulleys with axial slots?

[Perra.S]

Hey Per-Erik, seeing your practice roads makes me jealous. I've looked it up:
Zweden: . . . .20 inhabitants per km².
Netherlands: 448 inhabitants per km². It's a wonder we can even breathe :( .
(By the way: the number for New Zealand is 16. Lucky devils).

PS: Perra, did you try pulleys with axial slots?

Yeah, living on the countryside in Sweden is really nice. It's just to bad I don't do that anymore.

No, I never tried that. But it's certainly a thing that I will try in the future.

[wobbly]

Looks like Gannet Guns are popular in Sweden as well.

[TZ350]

60%methanol, 35%nitromethane, 5%oil ..... 90%nitromethane, 5%acetone, 5%oil

(Im just testing on gravel outside the garage so therefore the backwheel spinns the whole way, didn't got the chance to test it on asphalt because a too weak cylinderstud snapped and caused some damage)

There is some pulleys were there is room to machine in you're own slots. Like this one from a Yamaha Aerox, and because it's a std. part you're allowed to use it right?
http://mopshop.de/shop/product_info.php?cPath=1_327_1585_5_17805&osCsid=tgi229mb1ggs5g91mir0trpv33&osCsid=tgi229mb1ggs5g91mir0trpv33

Just love these small engines, turbo and nitro what fun.... and thanks for the link to the pullys

[F5 Dave]

. . . I am a bit worried about you getting more power though. . . .

We should talk.

[wax]

tbm has a rear pulley with straight slots from the factory. Its what we used on our race bike in the 24 hour.
It works awesome.

[Farmaken]

Got a bit excited about creating more Ex blow down and after a trial run in a sacrificial test barrel got stuck in and came up with this ( pic 1)

Also took on board the less is more comment from Wob a while back and with a pic of an Aprilia cylinder in hand and a pot of Devcon came up with this ( pic 3 )

Pic two is a standard unmolested cylinder

[Moooools]

We should talk.

Haha I have just had a bit of work done on the fiddy by RMS Engineering. It is pretty nice as it stands at the moment and is completely ridable without having to use the clutch. I think there is still a second to drop in lap time just with learning to ride the thing a bit better. And from what I hear you are a bit of a dodgy bastard Dave. :innocent:

[Perra.S]

tbm has a rear pulley with straight slots from the factory. Its what we used on our race bike in the 24 hour.
It works awesome.

You run a horizontal minarelli as well right? Have you any links to some shop where I can buy such a pulley? Because I never ever heard of that company here in Europe.

[FastFred]

Got a bit excited about creating more Ex blow down and after a trial run in a sacrificial test barrel got stuck in and came up with this

That is a clever looking piece of work.

[F5 Dave]

Yeah shame there is no room to do aux ex on the 50 as its is crying out for them, but the water jacket is too close.

Would be interesting to see the ex port interface with the aux, but it looks pretty good.

[F5 Dave]

. . . And from what I hear you are a bit of a dodgy bastard Dave. :innocent: Cool, Chris will see you right & does good work, but depending on your definition of dodgy. . .I've heard of sheep going missing in the area & returning Pregnent. I'm just saying.

[ac3_snow]

Got a bit excited about creating more Ex blow down and after a trial run in a sacrificial test barrel got stuck in and came up with this ( pic 1)

Also took on board the less is more comment from Wob a while back and with a pic of an Aprilia cylinder in hand and a pot of Devcon came up with this ( pic 3 )

Pic two is a standard unmolested cylinder

Shit your all ready fast enough! Looks really good will be interesting to see what you think after testing/riding it.
Are you going down to Wellington?

[Farmaken]

Yes would have been good to do before and after dyno testing but dont have one of those - will have to rely on on track comparisons.

Yes again to Wellington - not been there before and looks like a groovy track. See you there ??

[kel]

Also took on board the less is more comment from Wob a while back and with a pic of an Aprilia cylinder in hand and a pot of Devcon came up with this ( pic 3 )

Thats some good looking work, especially like the radius you have added to the inner corners of the transfer ducts. I imagine the motor is producing excellent torque what with the exhaust resonator and the triple port, would really like to see a dyno graph ...

[TZ350]

Got a bit excited about creating more Ex blow down and after a trial run in a sacrificial test barrel got stuck in and came up with this

Thats pretty good, I have ordered one of the mini angle grinders you put me onto, thanks.

[Yow Ling]

Thats pretty good, I have ordered one of the mini angle grinders you put me onto, thanks.

Could you post a link for them please

[twotempi]

Mini-angle grinder link - Yes please post .

[Farmaken]

Thats pretty good, I have ordered one of the mini angle grinders you put me onto, thanks.

Cheers TZ, thanks for doing it first and letting us follow :msn-wink:

Grinder is great, TZ will have to do the linky thing - I am still a computer retard

[husaberg]

Cheers TZ, thanks for doing it first and letting us follow :msn-wink:

Grinder is great, TZ will have to do the linky thing - I am still a computer retard

http://sharkshifter.com/zc/index.php?main_page=index&cPath=185_186&sort=20a&page=3
above is a random link not the TZ one
:msn-wink:
depending on your set up you may need to remove an extra http://

this triple port seems to be a great idea mmmmmm.......I wonder if it will catch on..................Maybe next week.
<img src="http://img853.imageshack.us/img853/7363/89413056.jpg" width="509px"/><img src="http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=251856&d=1322825780" width="326px"/><img src="http://www.deraceheldenvanweleer.nl/index.php?PHPSESSID=bbobq0gv5ajsklgubq0c2ehnu0&action=dlattach;topic=51.0;attach=16717;image" width="298px"/>
<img src="http://i32.servimg.com/u/f32/14/82/67/76/dsc06510.jpg" width="260px"/><img src="http://fpe-racing.pagesperso-orange.fr/Moteurs_fichiers/Cyl%20FPE1.JPG" width="365px"/><img src="http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=277704&d=1359624836" width="505px"/>

[TZ350]

Farmaken put me onto this.

277602

Sioux model 5977 1/8" collet right angle precision pencil die grinder from Progressive tools - www.e-progressivetools.com (http://www.e-progressivetools.com) E-mail jsgilbert1@msn.com ph. 336 933 9830 fax 336 993 9840

also

http://www.use-enco.com/1/3/pneumatic-pencil-grinder

also

http://www.browntool.com

[wobbly]

The only problem with the Sioux is its head is too big to fit a 50mm bore with a cutter installed.

The best tool for the job is this, though more expensive initially its the only way to get the job done.

http://ccspecialtytool.com/182a-mc-small-right-angle-handpiece-adapter.

The other issue is that even the 182 tool will not allow you to fit counter rotating burrs, by fitting them backwards into the head.

The only one that does this is the 1MC head, means you can rub the bur in both directions across the port roof to get equal cutting action on both sides of the cylinder.

http://ccspecialtytool.com/1mc-right-angle-handpiece

The 182 works fine in both directions with fine diamond cutters, or cotton polishing mops, but for hogging out tripple ports etc the 1MC is the best.

Whatever you decide you have to settle on 1/8 or 3mm cutters and stick with that for everything or buy expensive collets and change all the time - a butt pain, I know.

[Bert]

Here's something to have a giggle about (GPR thread):

277670


Huummmm Interesting.

now that the GPR DYNO is up and running it was time to test the GPR100 (TZR).
At Minefield the other weekend it was noticeable that the power dropped off during the mid range.
However none of us expected it to be as interesting as this.

Some work to do..... :facepalm:
Dyno plot is 6000 - 12000


The ignition curve and servo opening are attached.
So we leaned it off by dropping the needle (which slightly improved things); but me thinks ignition and servo adjustments may be required.

Specs:
TZR100, 95-RS125 pipe, Exhaust duration = 198, Inlets = 123, comp 13.2:1, crankcase volume ratio 1.55.

[Haufen]

It could be your powervalve opening too early. Doing a couple of dyno runs in fully open and fully closed position will show how much can be gained from the powervalve.

[wobbly]

Lots is wrong - running 500mV Hysteresis means the valve can be almost anywhere and the servo loop will not correct it.
Change to 100mV.
The PV is fully open at 9500, way too early in my opinion, as at 1/2 position the valve is almost useless due to leakage.
As detailed before, do a run with the valve fully down,one held open, and one at 1/2 height.
Then interpolate the positions for max power.
I would guess you will see the hole disappear with the valve fully down - as long as its not down too far.
Also the PV servo works way faster if there is only one or two points along the opening ramp, having more does nothing but slow it down.

The ignition curve is wrong as well.
The hole is at 10,000 with nowhere near enough advance for an engine making bugger all power.

Good thing is that you can do all the various tests of PV position and Ignition advance while sitting on the bike - on the dyno - and reprogram whilst its still running.
You can do every position and ignition combination in an hour, as long as the fan keeps the thing cool enough for consistent tests.

[kel]

[QUOTE=Bert;1130489544]Here's something to have a giggle about (GPR thread):[QUOTE]

22hp. More of a yawn than a giggle :lol:
But seriously, as Wobbly has outlined that dip should be fairly easy to resolve. Look forward to seeing the results.
So another bucket racer home built dyno is up and running, fantastic stuff :niceone:

[F5 Dave]

[QUOTE=Bert;1130489544]Here's something to have a giggle about (GPR thread):[QUOTE]

22hp. More of a yawn than a giggle :lol:
But seriously, as Wobbly has outlined that dip should be fairly easy to resolve. Look forward to seeing the results.
So another bucket racer home built dyno is up and running, fantastic stuff :niceone:

When I rode it it felt seriously low revving & not that fast - looking at the curve I think I was believing the lightweight tacho & changing up before the real power kicked in (Gee I'm a nice guy with other people's bikes). A shame as the chassis has more potential than my NF4 I am sure. With some moved controls, the dip gone & (most important) a 2 tooth smaller front sprocket, I could win local races on this.

[crazy man]

[QUOTE=kel;1130489697][QUOTE=Bert;1130489544]Here's something to have a giggle about (GPR thread):

When I rode it it felt seriously low revving & not that fast - looking at the curve I think I was believing the lightweight tacho & changing up before the real power kicked in (Gee I'm a nice guy with other people's bikes). A shame as the chassis has more potential than my NF4 I am sure. With some moved controls, the dip gone & (most important) a 2 tooth smaller front sprocket, I could win local races on this.going of the graft that every time you change gears it would drop down in hp so much that it took a long time to pull out of it , and it was geared for manfeild lol but like wobbly said it should not take to long to make it some what right

[TZ350]

Now there is another dyno out there competition is really hotting up, great stuff.

[F5 Dave]

Two weeks till next Kaitoke. I'll bet it has the same gearing on it.:Pokey: Here I'll even look up the JT pn pre 93 JTF1263, post 93 JTF558, sure there will be smaller options.

[crazy man]

Two weeks till next Kaitoke. I'll bet it has the same gearing on it.:Pokey: Here I'll even look up the JT pn pre 93 JTF1263, post 93 JTF558, sure there will be smaller options.do you want a bet

[Bert]

Lots is wrong - running 500mV Hysteresis means the valve can be almost anywhere and the servo loop will not correct it.
Change to 100mV.
The PV is fully open at 9500, way too early in my opinion, as at 1/2 position the valve is almost useless due to leakage.
As detailed before, do a run with the valve fully down,one held open, and one at 1/2 height.
Then interpolate the positions for max power.
I would guess you will see the hole disappear with the valve fully down - as long as its not down too far.
Also the PV servo works way faster if there is only one or two points along the opening ramp, having more does nothing but slow it down.

The ignition curve is wrong as well.
The hole is at 10,000 with nowhere near enough advance for an engine making bugger all power.

Good thing is that you can do all the various tests of PV position and Ignition advance while sitting on the bike - on the dyno - and reprogram whilst its still running.
You can do every position and ignition combination in an hour, as long as the fan keeps the thing cool enough for consistent tests.

Thanks Wobs (and others; just not Kel:confused:)
Some really useful info here; I'm looking forward to Saturday testing (and remembering to take my laptop)...
Didn't even think about the number of points effecting the servo response, now that you have said it the lights gone on. I might also recheck the base advance.

Anyway despite Kel making fun of me, I'll post up the next lot of results.

And yes blood good of crazyman to let me loose on his new fully working dyno


Just kidding Kel. :laugh:

[TZ350]

... there was some testing with methanol/nitromethane. I had some problems with the fuel not atomizing correctly so if I ever is going to try it again it would be with EFI. 60%methanol, 35%nitromethane, 5%oil and 90%nitromethane, 5%acetone, 5%oil

If its lean when running Methanol, I am not sure EFI will help.

Back in the day I ran an air cooled Suzuki TR250R on Juice. At 100% Methanol it ran to cold to vaporise all the fuel and consequently ran lean. Increasing the main jet did nothing and in the end there was raw fuel being blown out the exhaust pipes, other riders complained.

The trick was to blend the Methanol with Acetone until the latent heat of evaporation of the fuel blend left enough heat in the engine to evaporate all of the fuel properly.

Acetone has a latent heat of evaporation midway between Methanol and Petrol. Acetone has an Octane rating higher than Methanol and like Methanol, Acetone likes to be run rich.

Acetone is a good fuel and can be run on its own but check how your crank seals cope with it first, soak them in it to see if anything happens to them, Yamaha RD seals with the Teflon lips swell up and create air leaks, Suzuki ones seem OK.

In the end I found a 50/50 mix of Acetone and Methanol (20:1 Castrol R) worked well in the Suzuki but different engines require different ratios and the RD liked 100% Acetone. An air cooled Speedway engine I worked on had TZ750 barrels with big holes cut in the water jackets for cooling air to blow through, it liked a 100% Methanol.

You just have to experiment to find what an engine needs. It’s a balancing act between maximum chilling of the incoming air and enough engine warmth left to vaporise all of the fuel.

You could find that with EFI you can keep firing in ever more Methanol like I did with bigger and bigger main jets but if the engine is running to cold to vaporise it all, you will still be lean.

[Grumph]

Even better is Methanol/Toluene with a dash of acetone to dissolve the oil...

[Frits Overmars]

...Acetone is a good fuel and can be run on its own but check how your crank seals cope with it first, soak them in it to see if anything happens to them, Yamaha RD seals with the Teflon lips swell up and create air leaks.There's more than just the seals to worry about: synthetic main bearing cages do not always take kindly to hydrocarbons. E85 has caused problems and I even seem to remember a two-stroke oil that turned the cage material brittle....

[Perra.S]

If its lean when running Methanol, I am not sure EFI will help.

Back in the day I ran an air cooled Suzuki TR250R on Juice. At 100% Methanol it ran to cold to vaporise all the fuel and consequently ran lean. Increasing the main jet did nothing and in the end there was raw fuel being blown out the exhaust pipes, other riders complained.

The trick was to blend the Methanol with Acetone until the latent heat of evaporation of the fuel blend left enough heat in the engine to evaporate all of the fuel properly.

Acetone has a latent heat of evaporation midway between Methanol and Petrol. Acetone has an Octane rating higher than Methanol and like Methanol, Acetone likes to be run rich.

Acetone is a good fuel and can be run on its own but check how your crank seals cope with it first, soak them in it to see if anything happens to them, Yamaha RD seals with the Teflon lips swell up and create air leaks, Suzuki ones seem OK.

In the end I found a 50/50 mix of Acetone and Methanol (20:1 Castrol R) worked well in the Suzuki but different engines require different ratios and the RD liked 100% Acetone. An air cooled Speedway engine I worked on had TZ750 barrels with big holes cut in the water jackets for cooling air to blow through, it liked a 100% Methanol.

You just have to experiment to find what an engine needs. It’s a balancing act between maximum chilling of the incoming air and enough engine warmth left to vaporise all of the fuel.

You could find that with EFI you can keep firing in ever more Methanol like I did with bigger and bigger main jets but if the engine is running to cold to vaporise it all, you will still be lean.


The main reason why I want to run a EFI is that when you run so much nitromethane you need to deliver huge amounts of fuel to the engine and that is very hard to accomplish with a carb. When running 90% nitro I had to do many mods to the carb and I had to run a fuel pump to feed it, a normal fueltank setup didn't work. Without a fuelpump it emptied the carb in about 40meters of wide open throttle :facepalm:

And of course, I had to run extremely large needle- and main jets (on 90% nitro there was only the needle jet bored to 4.5mm, no main jet) and that resulted in useless atomizing of the fuel so if I'm right a fuel injector that instead deliver a fine mist of fuel would help a lot.


When running on pure methanol there was never any problems with fuel not atomizing correctly (because I still could run normal needle- and main jets), it started when I exceeded ~30% nitro with homemade jets and as you say there was raw fuel blown out the exhaust.

[TZ350]

I can see now why you want to run EFI, your work with the ""chemicals"" is very interesting. I have thought about trying a bit of nitro in the Beast one day on the dyno just for fun. Gigglebutton runs NOS in his 50 on occasions and gets a real boost.

The idea for the Beast, is that Nitro carries slightly more fuel than oxygen and that if an engine was running properly on petrol one could then just dribble some nitro in front of the carb and let it get sucked in or we could run the nitro through a power jet.

Any nitro that's sucked in will only make the existing mixture richer and as long as the compression and ignition are suitable it should run OK, should be fun to try on the dyno sometime.

[FastFred]

Its amazing what TwoTempi can dig out of his junk box.

277728

Now if we could just hack the water jacket off this sucker and glue some fins on with a bit of weld and maybe piston port/case reed it for a good old 6 speed TF125 engine/cylinder conversion we could have ourselves something to putter around on.

[FastFred]

I am sure its off a power restricted Italian old school domestic commuter bike so perfectly legal.

[husaberg]

Its amazing what TwoTempi can dig out of his junk box.

277728

Now if we could just hack the water jacket off this sucker and glue some fins on with a bit of weld and maybe piston port/case reed it for a good old 6 speed TF125 engine/cylinder conversion we could have ourselves something to putter around on.


I am sure its off a power restricted Italian old school domestic commuter bike so perfectly legal.

Ailirpa never heard of them although the dutch crowd do these.http://www.he-ja.nl/2007-RS125-intro.brits.htm
Aprilia top end on a Honda bottom end.
<img src="http://www.he-ja.nl/DSCN9245.JPG" width="340px"/><img src="http://www.he-ja.nl/DSCN9249.JPG" width="340px"/><img src="http://www.he-ja.nl/19-10-inro-21.jpg" width="340px"/>
<img src="http://www.he-ja.nl/19-10-inro-15.jpg" width="340px"/><img src="http://www.he-ja.nl/19-10-inro-17.jpg" width="340px"/><img src="http://www.he-ja.nl/19-10-inro-13.jpg" width="340px"/>
<img src="http://www.he-ja.nl/19-10-inro-14.jpg" width="210px"/><img src="http://www.he-ja.nl/19-10-inro-11a.jpg" width="300px"/><img src="http://www.he-ja.nl/19-10-inro-03.jpg" width="300px"/><img src="http://www.he-ja.nl/19-10-inro-24.jpg" width="300px"/>
<img src=" " width="340px"/>

The HONDA RS125 HE-JA A kit cost in the complete outfit € 9700.= exc. VAT

The B Kit is exactly the same as the A Kit, except the electronic. This one is to obtain from BPS or an other branch to rebuild it yourself. One can also use the standard eCU unit. Price € 6588.= exc. VAT.

It is also possible to obtain only the complete cylinder + Exhaust flange and cylinderhead.

The cost of this C Kit is € 3840.= excl. VAT.
Intersting if you added the disk valve crankcases another company (http://www.crp-racing.com/portal/en/kit-honda-disco-rotante.html) makes for the Honda RS125 you could have a Honda engine that is pretty much an aprilia (actually is anything on the crp engine Honda?)
http://www.crp-racing.com/portal/images/stories/Kit-Honda-Lamellare/honda-disco-rotante-3.jpghttp://www.crp-racing.com/portal/images/stories/Kit-Honda-Lamellare/honda-disco-rotante-4.jpg

Its amazing what TwoTempi can dig out of his junk box.

277728

Now if we could just hack the water jacket off this sucker and glue some fins on with a bit of weld and maybe piston port/case reed it for a good old 6 speed TF125 engine/cylinder conversion we could have ourselves something to putter around on.
But if someone was to cast their own cylinders..... the peanut gallery would no doubt chirp up and cry foul, not in the spirit etc....... i say f-em

Question for Frits or Jan (i see he pops in occasionally) Jan had mentioned a few times that the Crankcase volume for a reed or case reed would be smaller than the RSA RSW
How much smaller would it be? I realise you don't have your notes but i would be interested in knowing what the Reed Derbi was?

[TZ350]

Its amazing what TwoTempi can dig out of his junk box.

277728

Thanks for posting that, I am particuarly interested in the inside radius of the transfer ports.

277746 277747

The inside curves radius is important, as I understand it the wrong shape will promote flow separation, effectively narrowing the transfer duct.

I will have to look back and check on the angles but I think the transfer port (the smaller one) nearest the exhaust is angled up at 24 deg and what is the main transfer port on this cylinder which is next to the boost port and is angled up at 12 deg.

[TZ350]

Frits talks about that new school cylinders transfer port shape and angles. It worth checking the original post out because Frits posted more pictures and there was quite a bit of discussion about transfer ports at the time.


As we were on the subject of scavenging angles, now would be a good time to write something about the radial angles of the A-transfers.
Surely a duct with a radial angle of over 20° offers a smaller cross-section to the flow than a duct that enters the cylinder perpendicularly?
Yes it does. But there are two good reasons to angle it upward anyway.

First, perpendicular mixture streams coming from the A-ports would collide and slow one another right down. The upward angles provide for less velocity losses and less
pressure losses, so despite their smaller cross-section, upward ports may flow as much, if not more, than perpendicular ports.
(Now you may well ask why the B-ports do not get the same treatment; that is because the central scavenging column, resulting from all incoming scavenging streams together, must not have too much radial velocity, or the loop scavenging will result in a loop-loss into the exhaust).

Second, there is a thing called scavenging balance (I invented the word for my personal use, so this may well be the first time you ever saw it).
If you looked closely at the scavenging picture of the MB-cylinder I posted earlier today, you may have noticed that the 'radial scavenging directional resultant'
had a value of 101,045°.
90° would have meant 'straight up'; more than 90° indicates that the central scavenging column is leaning towards the exhaust side of the cylinder.
But we don't want that; it is bad for the scavenging of the rear part of the cylinder, and it is risky because it may provoke scavenging losses straight into the exhaust.

277748

But how can we prevent a scavenging column from toppling over to the exhaust side like the leaning tower of Pisa? Not by pushing against its basis, but by pushing higher up. Hence the radial angle of the A-ports. The pictures will tell the story. (If only the Pisa architect had known a bit more about two-stroke tuning....)

A link to Yamahas paper on whats important in transfer ports. A bit older school now but its basically the shape of transfer port us Bucketeers find in our old school TZR TF TS GP engines.



The Relationship Between Port Shape and Engine Performance for Two-Stroke Engines

277749

In case you missed it earlier. Here is a little bit of a gold mine:- http://www.2stroke-tuning.nl/media/
Port maps etc, some of its in German.

[TZ350]

But if someone was to cast their own cylinders.....

I am enjoying playing with the aircooled moter but I can see a H2O 100 in my future ....

[koba]

I am enjoying playing with the aircooled moter but I can see a H2O 100 in my future ....

I see one in mine too :yes:

[husaberg]

I am enjoying playing with the aircooled moter but I can see a H2O 100 in my future ....

I think and i could be well wrong that the Transfers or at least the b ports are smaller in the RSW vs the RSA the septum on some of the pictures i have seen are more rounded on the RSA too i think, but i could have that backwards?
will add pics and quote later. Can't find the bit i wanted but can frits confirm anything i always assumed the cylinder drawings from the Frits Files were RSW?


The duct entry area of the Aprilia cylinder's B-ports is slightly smaller than their port exit area. This stems from the old obligation to develop cylinders that had to fit the existing crankcases of the Aprilia RSW engine, of which there are hundreds around. the RSA engine did not have this limitation, but simply enlarging the B-duct entries disturbed the scavenging, so the ducts were left as they were (and remember: while the B-ports' exit areas are only open part of the time, the entry areas are open all the time).
The transfer timing is 130° for the A-ports (they are really close to the auxiliary exhaust ports) and 132° for the B-ports and the C-port.


Some more RSA125 development info from Jan Thiel

"No pressure transducers were ever used in our engine development.
And time/aerea was never calculated.
The port timings remained practically the same during 15 years!
What we did was trying different angles and radiuses, mainly onthe transfer ducts. I think we tried 40 different types of transfer ducts
that did not chanche the time/aerea. It was all about in which direction the charge entered the cilinder and how the tranfer streams influenced upon
each other! Also about 200 different exhaust pipes were tried. After 2004nothing much was changed but we improved with different power jet and ignition mapping. It seemed nearly impossible to improve the transfer ductsany more. The exhaust ducts were CNC machined, using different programs,
mainly to reduce exhaust duct volume. Also about 100 head designs were tried"

There is hardly an optimal ratio of duct area to port window. I generally try to obtain a value of 1,5 but when you look at the B-transfers of an Aprilia (A is the set nearest the exhaust; then come the B-ports, then the C-port opposite the exhaust) you will see that the entry at the cylinder base is almost a rectangle, with a width of 19mm and a 'length' (in riding direction) of 16 mm; that gives 304 mm².
The B-window in the cylinder wall has a width of 25 mm, a height of 13,2 mm and an upward angle of 10°; the effective port area is 325 mm²; it's bigger than the entry area 8).
Didnt calculate time area? Im guessing that means the time area requirement hasnt changed any in the last 15+ years.
So there you go its all about the transfer ducts, now where have I heard that before?
Check out the attached photos, I guess the idea of thinning the transfer duct bridge has gone out the window, and the exhaust duct hows that for a crazy shape

You want the aux ports as big as possible to have more blowdown.
You want the most blowdown with a limited exhaust timing in order not to lose power at low revs.But there are limits.
You have to keep away from the transfer ports to prevent fresh charge going into the aux. ports.
That is why their bottom is inclined.The same happens if you make the aux. ports too wide.You loose fresh charge.This also cools the exhaust gases, so you loose revs.Symmetry is also important.We tried a piston with a closed pistonpin hole on one side.
With this piston power was very bad!Worse than with a 'normal' piston!
Closed piston pins did not improve power at all revs.Only at some points in the power curve.Mostly at high revs.
At some points in the power curve you loose something, but not much.

With aux. ports you can use a lower exhaust port, so that you have more power at low revs.

What really counts is blowdown.
But discharging of the burned gases may not be complete until BDC.
In this case you get 'short circuiting' of the fresh charge from the transfer ports into the exhaust.
By using auxiliar exhaust ports you can improve blowdown quite a lot.
So that you might be able to raise the exhaust's 'floor'.This helps improve blowdown flow, as seen on a flowbench.In 2007 we started to raise the underside of the exhaust port.The first results were very promising!But at the end of 2007 I retired, so I could not finish what I started.The idea was to raise the exhaust underside as much as possible until power dropped.
And then, with a smaller exhaust port underside it might have been possible to widen the A-ports more
without losing the fresh charge into the exhaust.The ideal situation would, of course, be that all the burned gases are discharged from the cylinder beforethe transfer ports start opening.So it is difficult to have too much blowdown.But in trying to achieve enough blowdown you can arrive at a too high exhaust port.Which first causes power loss at low revs, and if exaggerated still more also a loss of max. power.Because of shortening the power stroke.

[TZ350]

If you say had a 158cc single 4 stroke with a really nice plain bearing bottom end. Custom light forged piston. Redesigned port layout. An ingitech allowing 14000 to 15000 rpm. Flowed head that can pump 32hp worth of air. Massive titanium valve's and huge cams and a close ratio 6 speed in a good frame and a total bike weight of 82kg. That should go ok don't you think.:innocent:

Thats what I want. Might be a bit loud.

I am starting to think the 4T boys might pull this off ..... I know of another project like this not far from us.


Why a plain bearing bottom end?


A plain Brg can carry more load and rpm, notice rpm .....

Rich's posts are carrying a big hint about where things are already at and are going to with some of the FXR's that are on the front row of the grid ......


Sounds cool. I know the KTM 250 dirt engine revs to 13000 all day with a normal bearing setup. Mr honda has gone plain bearing for the moto3 engine. Not sure what the others have done. There is plenty of power in the current engine setup its just up out of reach at the moment. Its all about chasing the weakest link.


Not sure at what rpm things get a little stupid on a single OHC 4 banger. 14500 sound like a good number.


And there is the key to what TeeZee is saying
150cc 4T at 14500 needs over 200psi bmep to go mid 30s crank power.
Full house intake and exhaust tuning, mega cams, tons of TDC overlap, and you think the 2T powerband is too narrow at 30Hp,try riding that FXR.
Sure Kev could make it happen, but I think the reliability cost and rider ability needed is out of reach to most.

There are close ratio kits available in Thailand for their version of the FXR150 commuter bike to convert them from commuters to the "sport bike feel" whatever that means.

BMEP is the guide, so, yes getting more difficult but it looks like its not impossible to pump things up a bit more than the current 24rwhp. Lighter, good handling bikes, well the 4T boys already have those, it will be interesting to see how things develop on the 4T front.

And from the man who is best placed to know .......


21hp in a RS still gets blown away on big track and only just hangs onto Gavs FXR on the short tracks, 25hp is needed to live with any sorted 4T ! Nathaniel was on The faster of the 2 bikes at Taupo and that has 25hp and it's a shame he could not hold on to it for a few more laps ..

[husaberg]

I am starting to think the 4T boys might pull this off ..... I know of another project like this not far from us.

There are close ratio kits available in Thailand for their version of the FXR150 commuter bike to convert them from commuters to the "sport bike feel" whatever that means.

BMEP is the guide, so, yes getting more difficult but it looks like its not impossible to pump things up a bit more than the current 24rwhp. Lighter, good handling bikes, well the 4T boys already have those, it will be interesting to see how things develop on the 4T front.


If you say had a 158cc single 4 stroke with a really nice plain bearing bottom end. Custom light forged piston. Redesigned port layout. An ingitech allowing 14000 to 15000 rpm. Flowed head that can pump 32hp worth of air. Massive titanium valve's and huge cams and a close ratio 6 speed in a good frame and a total bike weight of 82kg. That should go ok don't you think.:innocent:


sounds like a nice wee small budget like build doesn't it.
custom forged piston ???????????$500
TI Valves ???????$200
Custom porting and head flowing(assuming its not ya Bro)????? $300-500
Full house cam (assuming its not ya Bro) ???$250
Close ratio box ????????$300+
Plain bearing bottom end and oil pump mods 300+????????
Special valve springs and retainers ????????200+
I am glad Dorna went the 4 stroke way as they are far cheaper aye.............
From memory the NR500 valve collets were 2000 pounds back in the early 80's but they did have 64 of them.

[richban]

sounds like a nice wee small budget like build doesn't it.
custom forged piston ???????????$500
TI Valves ???????$200
Custom porting and head flowing(assuming its not ya Bro)????? $300-500
Full house cam (assuming its not ya Bro) ???$250
Close ratio box ????????$300+
Plain bearing bottom end and oil pump mods 300+????????
Special valve springs and retainers ????????200+
I am glad Dorna went the 4 stroke way as they are far cheaper aye.............
From memory the NR500 valve collets were 2000 pounds back in the early 80's but they did have 64 of them.



Change of plan. Develop the current bike to make more power and get it to handle better. Exhaust ignition and intake are all untested really. Then ride it like I stole it.

I will be building another engine in the next couple of mouths. refreshing old faithful to the spec I have now. Maybe look at the gearbox then. Not much time to play at the moment.

[crazy man]

if the fxr150 was my pet projected l think l could get some real good power out of it but getting a bored of it now ,got heaps of things l want to build now

[husaberg]

Change of plan. Develop the current bike to make more power and get it to handle better. Exhaust ignition and intake are all untested really. Then ride it like I stole it.

I will be building another engine in the next couple of mouths. refreshing old faithful to the spec I have now. Maybe look at the gearbox then. Not much time to play at the moment.

nah your motor is fast enough as it is thank you i was only being facetious.
Can you ball park the figures though.... assuming the buyer is not Kev's bro...........

[Yow Ling]

That's next week.........

Still waiting !!

[husaberg]

Still waiting !!
so am i..................:laugh:

ok here is a blurred out image for you.........


So realisticly what is the cost of casting a cylinder

the sand guy is NZ$1 per cc, the cad guy will want a grand or 2 , the foundry will probably drop the cores , back to sand guy, machining the casting $500 ?, plating the hole 500? pv blades? porosity could be an issue, Ill bet we all just keep sleeving cylinders in spite of the problems stuffed RGV cylinder $40, sleeve $100, some glue 20.00,


Imaging the hating if you turned up with a $3k barrell

Should i put you down for 4 or 6 then?
I believe a more economic way is to buy borrow make modify construct a mold a tool a flask a core and a model then cast up as many or as few as you want?

[Perra.S]

I can see now why you want to run EFI, your work with the ""chemicals"" is very interesting. I have thought about trying a bit of nitro in the Beast one day on the dyno just for fun. Gigglebutton runs NOS in his 50 on occasions and gets a real boost.

The idea for the Beast, is that Nitro carries slightly more fuel than oxygen and that if an engine was running properly on petrol one could then just dribble some nitro in front of the carb and let it get sucked in or we could run the nitro through a power jet.

Any nitro that's sucked in will only make the existing mixture richer and as long as the compression and ignition are suitable it should run OK, should be fun to try on the dyno sometime.

I have thought about that too, sounds good in theory but has never heard of anybody actually trying it. I hope you try it sometime, would be fun to know if it works.

When I think about it I have heard of one guy who tried it but he also had an extra servo controlled throttle body that opened at the same time as the injector started spraying metanol/nitro but it was running lean and only resulted in a epic seizure after a couple of meters. Pure nitro with no extra air would hopefully be a better way to go.

[richban]

nah your motor is fast enough as it is thank you i was only being facetious.
Can you ball park the figures though.... assuming the buyer is not Kev's bro...........

I reckon for a plain bearing bottom end and close ratio 3.5K. Top end if you sent it off to get done 3k maybe 3.5. So lots. You could spend 10k buy the time it was running nice. Dry sub conversion and all that. If you did all the porting and engine work maybe half that.

[Neal]

so am i..................:laugh:







Too blurry for me to see anything , :facepalm: any more sneek pics ?

[husaberg]

Too blurry for me to see anything , :facepalm: any more sneek pics ?

yip..............:no:

[F5 Dave]

I am sure its off a power restricted Italian old school domestic commuter bike so perfectly legal.
So who are we today?

That is incredible. There is the RS125 commuter bike that has been around for aeons & of course their GP RS equivalent. I've seen in neither but that is pretty insane porting for a road bike.

[Flettner]

I'm not sure of the rules any more, in my day alcohol was allowed ( in the bike ) and two cylinder water cooled 100 was also allowed ?? Can you still run a water cooled twostroke twin??

[koba]

I'm not sure of the rules any more, in my day alcohol was allowed ( in the bike ) and two cylinder water cooled 100 was also allowed ?? Can you still run a water cooled twostroke twin??

Yep, not on alcohol though.

100cc (plus something or other for an overbore) = Wassercooled OK and unlimited carb size

125cc (Again with some overbore added) = Aircooled and limited to 24mm carb or equivalent.

[Flettner]

So, no problem with twins then. Thanks.

[koba]

I finally measured my port timing, I had calculated that the transfers would be at 124° and once measured I found them to be... 124°!
Quite happy about that.

The stink part, in the current build, is that I went (maybe) too far on raising the exhaust so I'm at 195 rather than an expected 192.

My plan was to raise the barrel a fraction more to end up at around 132/198.

I'm not too sure if I should raise it further or not now, widening transfers is another option but easy to cock up; especially given my experience/tools.

This is all not as important as addressing the other issues holding the engine back, I've hacked out the aux inlet ports further (rough cut for testing, refinement to come) and machined a head to hopefully be better than the almost std head I've been running.
All I did with the old one was lap it on a piece of glass until I had .8mm Sqush and around 7.5cc. That took ages!

Oh, plus there is the gannet gunned pipe to try and maybe a secret something...

[koba]

So, no problem with twins then. Thanks.

Yeah, 125 or 100cc twins really have some good potential...

[Sketchy_Racer]

I finally measured my port timing, I had calculated that the transfers would be at 124° and once measured I found them to be... 124°!
Quite happy about that.

The stink part, in the current build, is that I went (maybe) too far on raising the exhaust so I'm at 195 rather than an expected 192.

My plan was to raise the barrel a fraction more to end up at around 132/198.

I'm not too sure if I should raise it further or not now, widening transfers is another option but easy to cock up; especially given my experience/tools.

This is all not as important as addressing the other issues holding the engine back, I've hacked out the aux inlet ports further (rough cut for testing, refinement to come) and machined a head to hopefully be better than the almost std head I've been running.
All I did with the old one was lap it on a piece of glass until I had .8mm Sqush and around 7.5cc. That took ages!

Oh, plus there is the gannet gunned pipe to try and maybe a secret something...

.8 is very conservative, I would have thought something around the .4-.5mm would be closer. If you ever need machine work done on the MB, let me know, i have jigs for machining the heads and barrels, and even one for milling the rear aux ports/reed cage in (takes about an hour to mill and god knows how long to grind!)

[koba]

.8 is very conservative, I would have thought something around the .4-.5mm would be closer. If you ever need machine work done on the MB, let me know, i have jigs for machining the heads and barrels, and even one for milling the rear aux ports/reed cage in (takes about an hour to mill and god knows how long to grind!)

I'm not God but it took me about 43 hours for the first version.

Going to build a jig of my own for the aux port now that the dirty drill-press/hoary-mill conversion is complete.

Cheers all the same.

The .8 was the done-by-hand-with-few-tools version, I've now made a jig and used a lathe to get it to .6 and a better shape chamber.

I'd post some pic's but I dropped my iPhone in the shitter; post shit.

[TZ350]

My plan was to raise the barrel a fraction more to end up at around 132/198.

I'm not too sure if I should raise it further or not now, widening transfers is another option but easy to cock up; especially given my experience/tools....

These numbers are simalar to yours ...

277784

Transfers open 114 ATDC for 132 Duration A port angled 12 deg up (Std), B port 5 deg up.
Exhaust opens 80 ATDC for 200 Duration and 72% port width.
Inlet opens 145 BTDC closes 80 ATDC 32mm equivalent dia port window, 24mm taper bored carb, 135mm inlet tract from RV to bellmouth.
Old Honda RS125 exhaust.

We got most of the improved performance from widening the rear transfers as much a possible and opening the exhaust port to 72%

[Frits Overmars]

Just love these small engines, turbo and nitro what fun.... and thanks for the link to the pullysHere you go, TeeZee: 'small' engines, turbo, nitro and pulleys. The pulley transmission keeps up fairly well with the engine power, wouldn't you say?
http://www.youtube.com/radarruns

I almost forgot: the indicated speeds are mph :shifty:.

[rgvbaz]

Here you go, TeeZee: 'small' engines, turbo, nitro and pulleys. The pulley transmission keeps up fairly well with the engine power, wouldn't you say?
http://www.youtube.com/radarruns

I almost forgot: the indicated speeds are mph :shifty:.

Fuck!!!!!!

[TZ350]

Impressed ....

[TZ350]

<iframe width="560" height="315" src="http://www.youtube.com/embed/FOuh6D5Q_4I" frameborder="0" allowfullscreen></iframe>

Some on board shots from the Island.

[Farmaken]

Might be useful

[TZ350]

Add some allowance for material for a radial head nice swooping transfers and decent size cooling fins?:)
But are the drawings in the stuff Frits posted enough to work from?
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=256478&d=1328094021
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250856&d=1321524095

I think this is the drawing or at least similar to that cylinder TwoTempi found in his junk box.


Its amazing what TwoTempi can dig out of his junk box.

277728

Now if we could just hack the water jacket off this sucker and glue some fins on with a bit of weld and maybe piston port/case reed it for a good old 6 speed TF125 engine/cylinder conversion we could have ourselves something to putter around on.


Thanks for posting that, I am particuarly interested in the inside radius of the transfer ports.

277746 277747

The inside curves radius is important, as I understand it the wrong shape will promote flow separation, effectively narrowing the transfer duct.

I will have to look back and check on the angles but I think the transfer port (the smaller one) nearest the exhaust is angled up at 24 deg and what is the main transfer port on this cylinder which is next to the boost port and is angled up at 12 deg.

Its worth checking out Frits comments in the link below.


Frits talks about that new school cylinders transfer port shape and angles. It worth checking the original post out because Frits posted more pictures and there was quite a bit of discussion about transfer ports at the time.

A link to Yamahas paper on whats important in transfer ports. A bit older school now but its basically the shape of transfer port us Bucketeers find in our old school TZR TF TS GP engines.

[Flettner]

TZ 350 , be careful what you wish for.

http://www.youtube.com/watch?v=5DyPUqr4-CU&feature=share&list=UUoYhqhrdK9On_IfKGD31hGA

[koba]

These numbers are simalar to yours ...

277784

Transfers open 114 ATDC for 132 Duration A port angled 12 deg up (Std), B port 5 deg up.
Exhaust opens 80 ATDC for 200 Duration and 72% port width.
Inlet opens 145 BTDC closes 80 ATDC 32mm equivalent dia port window, 24mm taper bored carb, 135mm inlet tract from RV to bellmouth.
Old Honda RS125 exhaust.

We got most of the improved performance from widening the rear transfers as much a possible and opening the exhaust port to 72%

Cheers.

I'm at 70% exhaust at the moment and will likely soon go wider.

Widening transfers is going to be a bit harder to achieve, I'm currently mulling that one over.

[2T Institute]

Its amazing what TwoTempi can dig out of his junk box.

277728



He has some nice stuff in there

[teriks]

So that you might be able to raise the exhaust's 'floor'.This helps improve blowdown flow, as seen on a flowbench.In 2007 we started to raise the underside of the exhaust port.The first results were very promising!But at the end of 2007 I retired, so I could not finish what I started.The idea was to raise the exhaust underside as much as possible until power dropped.
And then, with a smaller exhaust port underside it might have been possible to widen the A-ports more
without losing the fresh charge into the exhaust.
Interesting stuff, this have been around on MB40 cylinders for quite a few years. (think i got my first around 2001-2002 or so, but memory is vague.)
Great to hear the theory behind!

Even more radical things were tested I have been told, like an additional transfer port below the export floor. That did not make it to production though.

[Frits Overmars]

Interesting stuff, this have been around on MB40 cylinders for quite a few years. (think i got my first around 2001-2002 or so, but memory is vague.) Great to hear the theory behind!
Even more radical things were tested I have been told, like an additional transfer port below the export floor. That did not make it to production though.Here it is: the MB40-6port. What is your link with MB40 engines, Teriks? Do you take part in F3D competition? If so, under which name?

[TZ350]

Widening transfers is going to be a bit harder to achieve, I'm currently mulling that one over.

For Transfers its Wobs or is it Frit's catch phrase, "wide and low" to get the specific blow down time area required (STA).

Somewhere else I read that low transfer ports work better than higher ones of the same STA.

[Frits Overmars]

... I read that low transfer ports work better than higher ones of the same STA.The lower the transfer timing, the less risk of too-early returning exhaust pulses shoving the cylinder contents back into the crankcase.
In short: lower transfers give a better powerband, all other things being equal (which of course they never are).

[koba]

For Transfers its Wobs or is it Frit's catch phrase, "wide and low" to get the specific blow down time area required (STA).

Somewhere else I read that low transfer ports work better than higher ones of the same STA.


The lower the transfer timing, the less risk of too-early returning exhaust pulses shoving the cylinder contents back into the crankcase.
In short: lower transfers give a better powerband, all other things being equal (which of course they never are).

Yah, it show very clearly in a wave function of MOTA how they are flowing the wrong way until almost BDC!

[TZ350]

Page 710 .... links list to go here.


Suzuki GP125 and GP125U service manual... all 136 pages of it. It's a large file (for those who still use windows 98) at 18.0 MB

Suzuki GP125 Service Manual (http://christophercain.cc/b/suzuki-gp125.pdf)

Crank Case Volume


Most of the volume is concentrated in the transfer ducts. Then there is the volume inside the piston of course, and the 1 mm shear-avoiding clearance at all surfaces of the crank.

But that is not nearly enough volume. If you take another look at the Aprilia crank below left, you will notice that the space between the crank webs is the same as the space needed for the big end bearing.

277891

In other words: the crank webs have flat insides, good for another 60 cc or so, if I remember correctly.
Additional benefits: the con rod has an easier time pushing the mixture aside as it moves between the webs, and the big end bearing gets a lot more cooling and lubrication because it is not shrouded in any way.

Because there are no overhung bobweights, the crank webs are stuffed with tungsten to get the balance factor right. In the RSA125, the con rod was lengthened from the RSW's 115 mm to 120 mm to create even more crankcase volume.

The paddling is a mixed blessing; it creates aerodynamical drag but it also greatly improves the homogenity of the mixture.

Smooth, full-circle crank webs have the advantage that there is little mixture hiding in nooks and crannies. An example of it's importance: in a certain engine there were 20 mm spaces between the crankshaft bearings and the seals. these ill-accessible volumes acted as pneumatic dampers on the crankcase pressure fluctuation. Filling those volumes with plastic bushes gave a measurable improvement.

Summary: you need a large crankcase volume. Ideally all of this volume should be situated in the transfer ducts. In real life you will also need to lodge part of this volume between crankshaft and piston, i.e: use a long con rod. Avoid nooks and crannies. Crankshafts should be small and smooth. Big end bearings must never be shrouded by recesses in the crank webs or by stuffers.

The picture right below shows, wait for it, an RSA125-crank with stuffers...

277892

After Jan Thiel went into retirement in 2008, some geniuses at the factory grabbed their chance to 'correct' the errors that Jan left behind, without even testing the result because 'everybody knows the smaller the crankcase volume the better'. But they never could understand why a 2011 RSA125 was slower than a 2007 model (just look at the 125 cc top speeds on any GP-track). O, the joy of working with Italians.....





277890

The Red line is the smaller crank with 2mm clearance. I am not sure why the improvement is all at the bottom end and drops of earlier at the top.

Helmholtz frequency, my dear Watson. The smaller crank will give the pipe more crankcase volume to breathe from. This larger volume will also lower the resonance frequency of the inlet system, hence the drop at high rpm. It can be compensated with a shorter inlet tract, a bigger carb diameter and a later inlet closure. To put it real simple: if you have more volume, you need more time to fill it. But more time, i.e. later closure, has adverse effects at low revs. So my preference is a shorter tract (unless you go the 24/7-way and employ a reed for the low revs, and swing it out of the way at high revs).



To put it real simple: if you have more volume, you need more time to fill it.
Specific Time Area explained in 12 words. It's not yet as short as E=mc² , but I'm working on it.



so if TZ is working with a 24mm carb restriction he has likely found the limit of crankcase volume.

You're welcome, Dave.To the superficial reader that would seem as if the crankcase volume was too large. I would prefer to formulate it like this: TZ350's combination of crankcase volume, inlet tract length, inlet diameter and inlet timing is running out of breath at high revs.
I would rather shorten the tract, increase the diameter (if allowed) or lengthen the timing, in that order, and preserve (or even enlarge) the crankcase volume.


For example , the proven need for huge case vol in a full house race rotary valve engine, isnt even close to being a positive element in a stocker reed valve engine with seriously crap transfer ducts.

Quite the opposite will produce better power in that scenario.
The smaller case vol gets the flow going sooner and more effeciently when the duct geometry is compromised , but then of course peak power cant be the object of the end game, with that upsetting mechanical limitation.


Flowing the wrong way between Transfer Open and BDC is not the result of a too-early returning exhaust pulse, but of insufficient blowdown time.area.

What I meant was the instant just before Transfer Closure. The stuffing pulse from the exhaust should not arrive at the cylinder just yet, but at rpms under the powerband it will, raising the pressure in the cylinder while the transfers are still open.

So the fresh charge gets pushed back into the crankcase, leaving little of it in the cylinder. And on top of that, just after the transfers close, that stuffing pulse reverses sign and direction, and sucks what little charge is left in the cylinder, out...

Loss of heat should be avoided all right, but if you want power, it is more important to avoid detonation. The part of the exhaust duct where washed-through fresh charge temporarily resides, should be kept cool to avoid heating up that charge.

And it is much simpler watercooling an exhaust duct that is part of the cylinder, than cooling a duct that is part of the pipe.....


The det amp is very selective about displaying real deto signals.
You simply wind in the sensitivity such that the two greens are on and then the orange will tell you where you are getting close
to a knock.
Wind up the sensitivity again and the red will come on in the same spot as the orange did before.
Pull out a degree or two at that rpm and the red will go out - leaving the orange semi warning.
Keep doing this till the curve is optimised.
It works the other way as well, no orange and you can be sure you dont have enough advance at that point.
Then you can run the earth line back to the Ignitech with only one or two degrees of deto retard a a failsafe.
If you try to run say 3* of retard with the sensor output connected to the Ignitech, it works so fast the light never comes on, so you cant see whats happening.

P558


The shock waves from deto will be transmitted right thru the cylinder and the case.
I have seen many times where for no apparent reason the head or barrel studs loosen off - not because they weren't torqued correctly, but due to the
gasket being crushed momentarily from deto.
Many cars have the det sensors on the side of the block, some with multiple sensors for cylinder pairs.
All that happens when the sensor is further away from the chamber is that the shock intensity is reduced, so the sensitivity of the amp must be wound up - not an issue.

P559


Lambda is not a reliable tool for any length of time in a 2T.
The heated ones last a bit longer but no matter what probe type is used they get contaminated and don’t read correctly in a very short time frame.
EGT is very simple. If you find peak power at say 1240* ,and know what the RAD was on the dyno, then its easy to construct a jetting pattern.
Every 3% rad = 1 jet size in a Kehin or Dellorto that use metric sized jet holes.
Always start on the rich side and jet down to the set EGT.
Best example I can give was at Vegas World Kart Champs.
In practice we went down one or two jets every run - as long as we saw a temp rise around 50* per jet,and the ground strap mark was clean at 3/4 length, then we were making more power.
At RAD 101 we had 1260, going one more only raised egt about 20* so NFG going there.
This was a 162 jet before we changed.
On qualifying morning it was cool and RAD104 - up one jet to 165 and we saw 1255 - on the money, qualified 2nd by 0.003 sec.
First race after lunch was RAD98, down 2 jets, won the first heat easily and saw 1265* and immediately were accused of cheating, for blitzing the Yank Champ down the shute..
He hadn’t jetted down enough for the hot afternoon RAD change.
Its that simple, once you have a baseline.
You can use the egt and the CHT as well, but that’s another story.


Have tried the remote hose to the Lambda thing and although the probe lasted better it was slow responding.to the extent that it is impossible to log the Lambda
output against rpm/Hp on the printout.
The reading I think was about 2000 rpm behind the engine when accelerating at 300 rpm/sec.
Dynojet has an expensive add on kit that uses a pump to draw the gas thru a tube that goes in the muffler, this has a filter element in it so should make the probe reliable.
But it doesnt work on a 2T - even apart from having something affecting the test by altering the outlet area of the muffler itself..
I have seen one Dynojet session where the customer had to pay for 2 probes in a 4 hour test cycle. NFG.

Re using EGT and CHT.
The only probes that are worth shit come from Exhaust Gas Technologies.They guarantee them for 2 years,and I have had no problems since changing to them.
They sell probes to Nascar/IRL/F1/MotoGP teams with a guarantee - the only guys to do this with exposed tip,high speed temp sensors.
The company sells Digatron gauges on Ebay,and having just started to use one with 2 screens and 5 functions - im sold.
The ones sold by Mychron etc for kart use are crap, seen several brand new setup last two laps.

Using the two gauges together,especially if you have say a Digitron data logging gauge,makes jetting much easyer.
Basically when the jets are rich, both egt and cht will rise then fall together,when doing a full throttle all gear run.
You can keep dropping jets and be sure that all is well as long as they both rise together - with the one caveat I stated above.
One Keihin main jet size should lift the egt around 50*F, if you only get 20* rise from a previous jet then what is happening is this.
There is only "x" amount of energy in the fuel ingested.This can end up in the trapped,expanding gas - making power.
It can end up in the water, via the head and cylinder wall,and depending upon the com or ignition point,alot simply exits the port and heats up the pipe.
BUT - as soon as you go overly lean,the combustion pressure/temp gets to a point where instead of heating the combustion charge, the flame front starts creating free radicals.
This uses a huge amount of the available energy,and instantly the egt drops.
Once free radicals have formed,they keep the process going,causing destructive deto to get worse and worse - thus the egt drops thru the floor.
You need exposed tip,fast probes to see this quick enough to save the engine.

Thus on the gauge,the CHT keeps rising fast,but the EGT slows and can drop down again.
In the above example I gave, the egt only rising 20*F pointed instantly to the fact that we were approaching deto point.
By watching the two temps track upwards together it is real easy to get a handle on what the engine wants, to make peak power - just short of deto.


CHT is dead accurate on a watercooled head as far as the rising temp is concerned.
The washer reads the heat load into the plug,its a bit slower than on an air cooled engine but the data is still valid.
More important is the fast response needed for EGT tracking,so you see immediately the temp slowing and then dropping when deto sets in.

The A/F meter is no different than the Lamda readout - the sensor soon dies due to contamination of the sensing surface.NFG.

The last injection setup I worked on we built an interface for the ECU that converted the EGT reading to the Lambda scale that the computer recognised.
This worked well on a Jetski setup,that is usuall all go or none.


Welp, I guess it is about time I contribute something to this forum...

Don't want to step on Wob's toes, but...

I have used a lot of the data loggers that are available (Motec, Aim, Digatron, Pi, CDS, Racepak) and...

The Mychron is a good starter setup, but if you decide to go beyond the basic logger and GPS, expansions are expensive and limited. I outgrew mine in a year... Most of the issues like Wob mentioned are actually just due to poor leads: user setup, and not properly strain relieved, yellow tc connectors not tight (yeah they come from the factory like that..) Easily fixed before you install with some silicone and shrink tubing. You don't have to have the Digatron to use the good open tip EGT's Wob mentioned, any logger with k-type will work. (And Yes, the open tip E.G.T. egt probes are as good as Wob says)

The best bang for your buck, full on data logging is without a doubt the AIM Evo4 (same guys as Mychron). Comes with the GPS, and has virtually unlimited expandability (number of channels). The best part is you can run whatever sensor your heart desires or can dream up (differential pressure for aero, ultrasonic distance, tire temps etc.) Price is close to the Mychron, gps, and an expansion module! And AIM has the most user friendly software I have used. If you want to get beyond the 3 basic temps, this is the ticket. Great stuff.

The only thing better is a full on Motec system, awesome stuff but WAY out of the price range for the average racer.

Haven't personally sorted out the lambda completely yet (only run it twice), but they can work, the snowmobile guys have been using them successfully for years. What I have learned so far is keep the pipe temp up and engine clean so the sensor temp can stay up and not foul. If it sees a real rich condition for an extended period of time (like warming up engine for dyno run maybe?) you'll have issues.


The issue that your test doesn't address is that with pump gas you may be able to get away with 13:1 com.
With AvGas its just starting to work properly at 15:1 and this attribute will always far outweigh any advantage flame speed or whatever may be contributing from the pump gas scenario.

The other issue is that unleaded fuel works best with plenty of advance, no com, and rich as hell.
AvGas loves com, loves running lean and hates advance, so you need to spend days on the dyno just optimising for the fuel.
Much better things to be doing in making a fast reliable race engine I believe.


Robinsons book offers a nice little piece on optimising fuel, ignition and comp to suit different fuels using a variety of fuels, but i guess you already knew that

279248

http://books.google.co.nz/books?id=8CT89yyPIgcC&pg=PA92&lpg=PA92&dq=john+robinson+two+stroke+tuning+optimising+fuel s&source=bl&ots=xdh76foOoS&sig=Bj77-px7sFJyfNTn_fn2EIOiG9c&hl=en&sa=X&ei=8pkHUKeEK4mUiQeKisWgBA&ved=0CFEQ6AEwAA#v=onepage&q=john robinson two stroke tuning optimising fuels&f=false


http://www.tmkpackers.co.nz/index.php/site/product/acetone

Husa IPA (Isopropyl alcohol) is used to make Hash


PWM control of the powerjet is a very sexy use of technology,slowly ramping off the fuel flow against rpm, but in reality using a simple rpm controlled switched solenoid work perfectly fine.
Yamaha and Honda have used the switched powerjet since forever, its reliable and does the job.
Only issue you need to address is the jet size and switch point ( along with TPS value ).
Running Avgas as we are still allowed to do, means that the tuning is based around getting high egt numbers to create good power, with lots of com and advance - unleaded is the opposite..
Thus experience has shown that as leaded fuel works best with a lean condition at peak power, we only need to switch a small jet just past peak - to increase the pipe temp and
thus give better overev.
In the Keihin numbering this is in mm dia and switching off a .35 is perfect.
When running unleaded, as the GP bikes have for years, the fuel likes to be rich at peak to create the best power, thus we need to switch off alot of fuel flow to increase the pipe heat quickly enough.
In this case a .65 is needed to do the job.
On the dyno or on the track it is easy to tell if the switch point is a little too low, as it feels exactly like the bike has changed into another gear past 6th.
It jumps forward when the solenoid kicks in - making the fuel curve lean, too early.Do this enough - and bang.
Its critical to 100rpm, and is working perfectly when you dont feel it happen - the power just keeps going.
To do it on the dyno you have to run the bike in 6th to simulate the acceleration rate as seen in that gear on the track, and is easy to do running back to back run ups.
Changing the rpm number 100 at a time, lower in the Ignitech, reprogram on the fly and run again.
If the rpm is too high - nothing happens, as there isnt time for the heat to affect the pipe wave speed.


I was wondering about setting up the powderjet jetting. I have the Kehin solenoid powderjet modded the way you showed on this thread and the .35 jet recommented but because of other issues with my bucket I blocked it off with a soldered up jet and tuned it up as a nomal carb. Now say I used a 1.60 main jet on the nomal carb then I add the powderjet is it 1.60 main jet minus .35 powderjet = 1.25 main jet is that right?


Yep Mitre 10 is the simple answer to easy access to Acetone.
About a cup full in 5L does the job in AvGas.

Re the powerjet sizing the answer is NO NO NO.
Cant be bothered now but work out the AREA of a 160 main and subtract the AREA of a 0.35 powerjet.


Area 1.6 main = 2.010, less area 0.35 = 0.0962.
Main jet should now be 1.56,closest is 1.55 with the powerjet .
Try this without switching first to check equivalent egt to original setup.



EGT is very simple.If you find peak power at say 1240* ,and know what the RAD was on the dyno,then its easy to construct a jetting pattern. Every 3% rad = 1 jet size in a Kehin or Dellorto that use metric sized jet holes.
Always start on the rich side and jet down to the set EGT.

In practice we went down one or two jets every run - as long as we saw a temp rise around 50* per jet,and the ground strap mark was clean at 3/4 length, then we were making more power.
At RAD 101 we had 1260, going one more only raised egt about 20* so NFG going there.
This was a 162 jet before we changed.

On qualifying morning it was cool and RAD104 - up one jet to 165 and we saw 1255 - on the money, qualified 2nd by 0.003 sec.

First race after lunch was RAD98, down 2 jets, won the first heat easily and saw 1265* and immediately were accused of cheating,for blitzing the Yank Champ down the shute..
He hadnt jetted down enough for the hot afternoon RAD change.
Its that simple,once you have a baseline.
You can use the egt and the CHT as well, but thats another story.

Great description, but I'm a little confused. So on the dyno you saw 1240deg at peak power. I would have thought at that time you would err on the lower side of the temp.

But are you saying that that calibrates the guage & you try get close to that & then keep goin up until it stops rising linear for that final bit?

At this stage presumably if you have a det guage or counter you could get away from needing a CHT perhaps?


In answer to your question Dave.
Matters not how the best temp was derived,on track or on the dyno.
With the gauge running and say a 180 main,then going down to 178,if I only see a small increase in temp ( 20*F) then that instantly means
that more heat energy is being used somewhere - not in heating the Ex gas to make power.
If the original temp was 1240, then that will be the ref temp for any air conditions on any day.
With the example I gave we had a 3 jet spread during the day, a very cool dense morning,and a very hot dry afternoon.
In both cases the egt settled at around the same mark.One jet leaner and we would be in the danger zone - one richer and we wouldnt be the fastest by a mile as we were.


My new digatron data logger just arrived! Any specific tips for tuning with egt and cht? Ive read as much as I can find but if anyone has any words of wisdom I'm all ears...


Have tried the remote hose to the Lambda thing and although the probe lasted better it was slow responding.to the extent that it is impossible to log the Lambda
output against rpm/Hp on the printout.
The reading I think was about 2000 rpm behind the engine when accelerating at 300 rpm/sec.
Dynojet has an expensive add on kit that uses a pump to draw the gas thru a tube that goes in the muffler, this has a filter element in it so should make the probe reliable.
But it doesnt work on a 2T - even apart from having something affecting the test by altering the outlet area of the muffler itself..
I have seen one Dynojet session where the customer had to pay for 2 probes in a 4 hour test cycle. NFG.

Re using EGT and CHT.
The only probes that are worth shit come from Exhaust Gas Technologies.They guarantee them for 2 years,and I have had no problems since changing to them.
They sell probes to Nascar/IRL/F1/MotoGP teams with a guarantee - the only guys to do this with exposed tip,high speed temp sensors.
The company sells Digatron gauges on Ebay,and having just started to use one with 2 screens and 5 functions - im sold.
The ones sold by Mychron etc for kart use are crap, seen several brand new setup last two laps.

Using the two gauges together,especially if you have say a Digitron data logging gauge,makes jetting much easyer.
Basically when the jets are rich, both egt and cht will rise then fall together,when doing a full throttle all gear run.
You can keep dropping jets and be sure that all is well as long as they both rise together - with the one caveat I stated above.
One Keihin main jet size should lift the egt around 50*F, if you only get 20* rise from a previous jet then what is happening is this.
There is only "x" amount of energy in the fuel ingested.This can end up in the trapped,expanding gas - making power.
It can end up in the water, via the head and cylinder wall,and depending upon the com or ignition point,alot simply exits the port and heats up the pipe.
BUT - as soon as you go overly lean,the combustion pressure/temp gets to a point where instead of heating the combustion charge, the flame front starts creating free radicals.
This uses a huge amount of the available energy,and instantly the egt drops.
Once free radicals have formed,they keep the process going,causing destructive deto to get worse and worse - thus the egt drops thru the floor.
You need exposed tip,fast probes to see this quick enough to save the engine.

Thus on the gauge,the CHT keeps rising fast,but the EGT slows and can drop down again.
In the above example I gave, the egt only rising 20*F pointed instantly to the fact that we were approaching deto point.
By watching the two temps track upwards together it is real easy to get a handle on what the engine wants, to make peak power - just short of deto.

Page 562


CHT is dead accurate on a watercooled head as far as the rising temp is concerned.
The washer reads the heat load into the plug,its a bit slower than on an air cooled engine but the data is still valid.
More important is the fast response needed for EGT tracking,so you see immediately the temp slowing and then dropping when deto sets in.

The A/F meter is no different than the Lamda readout - the sensor soon dies due to contamination of the sensing surface.NFG.

The last injection setup I worked on we built an interface for the ECU that converted the EGT reading to the Lambda scale that the computer recognised.
This worked well on a Jetski setup,that is usuall all go or none.


Each engine is different but if a setup has the optimum com and the timing in the ballpark of 15* at peak power,then Avgas or leaded racegas around the equivelant RON
will always be maxed out at around 1250* - @ 150mm min from the port.
Unleaded likes to be alot richer and makes more power with more advance so that setup makes best power at around 1050.
Not enough com or advance, and the peak safe egt will rise, but power wont,it will just rev on more due to the higher wave speed.
But you have still got it wrong about the air on the day.
You can jet to get the optimum egt,no matter what the RAD says,and it will be in the same state of tune - just using all the oxygen in the air available and mixing it with the correct amount of fuel.
On a hot day,or low Baro, it will hit 1250 but simply make less power, due to less oxy and thus less fuel = less BTUs burned.

The 400 F3 we thrashed on the dyno and at 12,000 held by the dyno for around 30 secs it settled at 12000* F - 96 Hp with no fade.
Thus this is a good safe baseline for the new owner who may not have the tuning smarts to determine what is good or not - but if he has to change jets 3 times during a day
to see 1200 then he will be well on the way to learning what to do.



A whole bunch of interesting links on Bucketracers post.


Page 520 .... the last ten pages were mostly about what some wheels weigh, ATAC valves and crank stuffers.

[TZ350]

Yah, it show very clearly in a wave function of MOTA how they are flowing the wrong way until almost BDC!

I love engine development simulators.......:love: ... and what you can learn from them.

[teriks]

Here it is: the MB40-6port. What is your link with MB40 engines, Teriks? Do you take part in F3D competition? If so, under which name?
Thanks for the picture Frits, newer saw it in person, only spoke with Rob about it.
Name's Thomas Eriksson, if you cut a few letters here end there you end up with teriks ;)
I have been using Robs engines since 1999, was more active in F3D up till 2006 when priorities somehow changed a bit. Could be linked to getting a kid, house and change of work maybe?
At the moment I'm fiddling with a RI crankcase for the MB40-LS top end on the CAD. Ended up being a very long term project, but getting there. Next challenge is to get the parts manufactured.

//Thomas

[husaberg]

The lower the transfer timing, the less risk of too-early returning exhaust pulses shoving the cylinder contents back into the crankcase.
In short: lower transfers give a better powerband, all other things being equal (which of course they never are).


Yah, it show very clearly in a wave function of MOTA how they are flowing the wrong way until almost BDC!


I love engine development simulators.......:love: ... and what they can tell you.



http://www.deraceheldenvanweleer.nl/index.php?PHPSESSID=bbobq0gv5ajsklgubq0c2ehnu0&action=dlattach;topic=1260.0;attach=34187;image
This is some extensive full use of the available width (off pitlane first) but i never noticed it in the Jan and Frits thread before?



Jan Thiel Remember one thing of all the ports the transfer ports are open the shortest time.
And the quantity of air which it is intended is a good engine over the cylinder!
The speed must be high, it can not be otherwise.

That the flow bench is another story.
It turned out that most of the flow does not always give the most power.
The transfer currents 'collide' and inhibit each other that way.
Otherwise everything would go directly into the exhaust.
Also, the transfer ports wider, towards the outlet, gives a lot more flow.
But less power ......(i hope i translated that right husaberg)


Jan Thiel What preliminary conclusions about MOTA engine simulation.
There are a few strange things.

You also have the choice between a do, and not 'water-cooled' outlet.
Water-cooled means a well chilled, surrounded by water, exhaust duct.
The "engine" runs a 'chilled' exhaust duct much worse.
This is in stark contrast to what I practice seen.
The better we cooled exhaust duct, the more power and less detonation, very clear.


Plus as always a question For Mr Overmars.:bye:

I have always thought the exhaust duct is to be kept as short and as possible to limit he loss of heat? i are clearly wrong (obviously).
But why is this often repeated? Am i confussing volume with length i see the RSA was CNC'ed i guess to ensure it was exactly as per spec

[Haufen]

just stumbled upon this searching my library. I've got the whole paper, too, but the board won't let me upload it because it's bigger than 1mb.

thats a rather old paper though, with todays more modern combustion chamber shapes and squish areas, things might have changed. but the tendency should remain the same.

277841

[gamma500]

Here you go, TeeZee: 'small' engines, turbo, nitro and pulleys. The pulley transmission keeps up fairly well with the engine power, wouldn't you say?
http://www.youtube.com/radarruns

I almost forgot: the indicated speeds are mph :shifty:.

Do you have more pics and info of that sled? What kind of fuel system does that monster use?

[F5 Dave]

just stumbled upon this searching my library. I've got the whole paper, too, but the board won't let me upload it because it's bigger than 1mb.

thats a rather old paper though, with todays more modern combustion chamber shapes and squish areas, things might have changed. but the tendency should remain the same.

277841
ok so I wonder how one would test for that. Just on the dyno? Clearly you would have case heating added to the equation causing the initial drop off.

Drag race 2 strokes they don't always run with water as there's no point.

But here's the thing. I often find, & like my dirtbike is a prime example, but I see it on the dyno as well; the first run through a gear doesn't pull smooth. I don't think its loading up, or maybe it only loads up with cold cases, but after throwing it a run or two through the gears, its sweet.

It doesn't matter a damn, but it is curious. I'd just assumed its too cold. But the graph above suggests otherwise.

[Flettner]

Just trying to learn how this forum works.
http://www.youtube.com/watch?v=5DyPUqr4-CU&feature=share&list=UUoYhqhrdK9On_IfKGD31hGA
Now I see how videos are posted!

[Frits Overmars]

The lower the transfer timing, the less risk of too-early returning exhaust pulses shoving the cylinder contents back into the crankcase. In short: lower transfers give a better powerband, all other things being equal (which of course they never are).
Yah, it show very clearly in a wave function of MOTA how they are flowing the wrong way until almost BDC!Flowing the wrong way between Transfer Open and BDC is not the result of a too-early returning exhaust pulse, but of insufficient blowdown time.area.
What I meant was the instant just before Transfer Closure. The stuffing pulse from the exhaust should not arrive at the cylinder just yet, but at rpms under the powerband it will, raising the pressure in the cylinder while the transfers are still open. So the fresh charge gets pushed back into the crankcase, leaving little of it in the cylinder. And on top of that, just after the transfers close, that stuffing pulse reverses sign and direction, and sucks what little charge is left in the cylinder, out...


At the moment I'm fiddling with a RI crankcase for the MB40-LS top end on the CAD. Ended up being a very long term project, but getting there. Next challenge is to get the parts manufactured.Did you talk to Rob about it, Thomas? To my knowledge he did not plan production of Rear Intake crankcases for the MB40 LongStroke, but he is an extremely flexible person and as he has all the necessary tools, templates and moulds, it would turn out to be a lot cheaper if he would produce those parts himself.


I have always thought the exhaust duct is to be kept as short and as possible to limit he loss of heat? i are clearly wrong (obviously). But why is this often repeated?Loss of heat should be avoided all right, but if you want power, it is more important to avoid detonation. The part of the exhaust duct where washed-through fresh charge temporarily resides, should be kept cool to avoid heating up that charge. And it is much simpler watercooling an exhaust duct that is part of the cylinder, than cooling a duct that is part of the pipe.

Why are mistakes often repeated? Good question. Humanity and civilization would be a lot better off without that. We are probably simply not bright enough to recognize errors the first time they occur. But let's not get too philosophical yet; it's only monday morning here....

[teriks]

Did you talk to Rob about it, Thomas? To my knowledge he did not plan production of Rear Intake crankcases for the MB40 LongStroke, but he is an extremely flexible person and as he has all the necessary tools, templates and moulds, it would turn out to be a lot cheaper if he would produce those parts himself.
I did, a long time ago when I first started this project. Now I think my timing is kind of bad, my guess is that he's even more busy than normal, with the WC on home soil and all.
Actually I have found someone close by with a good workshop, who is also interested in these kind of things. Might not get too expensive for a few prototypes, but as with most skilled people, he's also very busy.

Guess I'll repeat a few of his past mistakes instead, and probably add a few of my own.

[TZ350]

277947 277948 277946

How to shorten a big end pin needed for a crank rebuild, just cut it off with a slitting blade, works a treat.

[husaberg]

Loss of heat should be avoided all right, but if you want power, it is more important to avoid detonation. The part of the exhaust duct where washed-through fresh charge temporarily resides, should be kept cool to avoid heating up that charge. And it is much simpler watercooling an exhaust duct that is part of the cylinder, than cooling a duct that is part of the pipe.

Why are mistakes often repeated? Good question. Humanity and civilization would be a lot better off without that. We are probably simply not bright enough to recognize errors the first time they occur. But let's not get too philosophical yet; it's only monday morning here....

I guess i deserved that with such an open ended question.:laugh:

I do recall Mr Frits saying if we are good we might see some more of the "Frits files"
Om some non Aprilia engines

[koba]

Flowing the wrong way between Transfer Open and BDC is not the result of a too-early returning exhaust pulse, but of insufficient blowdown time.area.
What I meant was the instant just before Transfer Closure. The stuffing pulse from the exhaust should not arrive at the cylinder just yet, but at rpms under the powerband it will, raising the pressure in the cylinder while the transfers are still open. So the fresh charge gets pushed back into the crankcase, leaving little of it in the cylinder. And on top of that, just after the transfers close, that stuffing pulse reverses sign and direction, and sucks what little charge is left in the cylinder, out...



Ahh, right, yes.
I'm starting to understand all this a bit better.

I plan to spend a while playing with the return pulse and seeing how pipe changes affect it's characteristics.
The next pipe I make will take this into greater consideration.
The current one is far from perfect but I'm quite happy with it for a first stab (so far).
I'm sure more study and experience will bear sweeter fruit.

The inadequate blowdown is the aspect that shocked me when I saw it in the SIM, even on simulations of competition engines with large blowdown area the eruption down the transfers is quite graphic!

[koba]

277947 277948 277946

How to shorten a big end pin needed for a crank rebuild, just cut it off with a slitting blade, works a treat.

Good to see the lathe bed protected from that nasty abrasive shit!

[cotswold]

277947 277948 277946

How to shorten a big end pin needed for a crank rebuild, just cut it off with a slitting blade, works a treat.

Thanks To TZ and Culley I now have a crankshaft almost ready. I was the entertainment this evening at team ESE's head quarters. I first had a play with the press and dismantled a couple of cranks that TZ wanted the rods out of, they go off with quite a crack and without much warning and Culley was sat waiting for my inevitable reaction, he nearly choked on his beer.
My rod kit needed surgery and the pin was shortened in the lathe with the help of a cutting disc, never seen this done before. The pin was then pressed into position, the first time I ended up with not enough free play ( which also amused my host no end as he had been expecting me to bugger it up ) so had another go with the aid of a 1 tho' shim and it came out pretty well. Have to go back thursday to balance it, I had a very enjoyable evening topped off by an un-named bucket racer turning up with his bike to set up his ignition, he provided the biggest laugh of the night and I may leave it to him to spill the beans or if I get enough requests I may blab.:yes:

[koba]

if I get enough requests I may blab.:yes:

Request one...

[husaberg]

Request two

Plus Neil (Fletner)
can you explain the Uniflow to us....
all casting i understand were made by you and what gearbox did you use for the 100cc
I must be honest i have never got my head around the uniflow...........

[2T Institute]

Just trying to learn how this forum works.
http://www.youtube.com/watch?v=5DyPUqr4-CU&feature=share&list=UUoYhqhrdK9On_IfKGD31hGA
Now I see how videos are posted!

Your a handsome devil Neil and do your own PR work as well :laugh: That sounds much better than the average aero engine

[TZ350]

I had a very enjoyable evening topped off by an un-named bucket racer turning up with his bike to set up his ignition, he provided the biggest laugh of the night and I may leave it to him to spill the beans or if I get enough requests I may blab.:yes:

It was a great evening having fun working on bikes .... but someone un named (and not me) has a confession.

I have seen plenty of ....... from 4T's to the point of it almost being normal for them, but never ever so much ....... from a 2T. :no: a first for everything I guess .... :laugh:

[RAW]

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=277755&d=1359754172

Frits, the radius at the bottom of the cylinder into the A and B transfers ? Why isn't there the same radius on the C port entry

[wobbly]

There is a rad on the C port - just hard to see clearly.
Look at the top right hand pic - I ringed the place you can just see it in Paint.

[cotswold]

Request one...

No names but, it involved a 2t with a new ignition fitted by using some kind of epoxy then DRILLING and tapping out the epoxy to bolt the ignition to. Sounds fine until the bike was left on it's side for a trip in the car, when it made the workshop it was dripping oil like grandads trumpie, when the ignition cover came off it dropped about a litre on the floor, not supposed to connect with the gear box, but somehow :Oops:

[TZ350]

.... it was dripping oil like grandads Trumpie, when the ignition cover came off it dropped about a litre on the floor .... :Oops:

It was :drinknsin a few beers and lots of good natured laughing about the new bike pretending to be a 4T. But it was a bit of a head scratcher :scratch: for the team figuring out what had happened, in the end it was Chambers who twigged to it :).

All good fun.

[RAW]

There is a rad on the C port - just hard to see clearly.
Look at the top right hand pic - I ringed the place you can just see it in Paint.

Thanks for the reply wobbly, yeh noticed the small rad, just wondered weather this is a planned radius size, ? for flow or if it may be larger than the pics show, more like the others and how this may have effected performance, that is if there is any proven knowledge into this.

Cheers All

[wobbly]

Here is the reason the radi work on the duct entries.
This is a YZ152 ( 60mm bore for open class kart ).
Any flow coming from under the piston or sitting above the crank enters the duct over a dead sharp edge.
Sharp edges are only used in aerodynamics for supersonic flow over jet wings.
There is no supersonic flow in a 2T transfer duct I know of.

[Flettner]

http://www.youtube.com/watch?v=uiXsPkP9jvw&feature=share&list=UUoYhqhrdK9On_IfKGD31hGA

This is a uniflow crankcase induction ( no super charger ) in operation. This shows that the uniflow cylinder scavenge principal is sound. I was told before I started this project that the exhaust piston would melt and the concept was floored. This engine ran for many hours in this boat, under load, 9200 rpm max. After warming up the engine it could be held at 9200 until it ran out of fuel. This engine had cast iron pressed in sleeves ( bad for heat transfer ) and home cast exhaust pistons ( LM 13 ). This was the first day in the water under load, so I was taking it easy, no full throttle.
Second part to the video is the next day out on the lake, this time full throttle was used ( near the end of the clip over the back of the lake ). As per usual ( low budget ) the home made CDI burnt out so that was the end of our second day testing.

[Flettner]

http://www.youtube.com/watch?v=BPr694nlUKE&feature=share&list=UUoYhqhrdK9On_IfKGD31hGA

This is the first startup of the 440 uniflow. 1997.

[crazy man]

hi Flettner, do you still have the 100 engine? dad still has the piston aluminum he got of you years ago lol

[Flettner]

http://i1056.photobucket.com/albums/t380/uniflow/IMG_0505.jpg
http://i1056.photobucket.com/albums/t380/uniflow/IMG_0504.jpg

These are cylinder castings for the next engine 650cc, rough machined, ready to be sent away for heat treatment.

[Flettner]

http://i1056.photobucket.com/albums/t380/uniflow/CCF06022013_00001_zps0f116803.jpg

Husaberg, here is a crude diagram of the uniflow concept, it gives you an idea at least.
I would say this is how the "Barker Headless" worked.

[Flettner]

Crazy Man, yes, as it happens I've just got all the 100 uniflow bits out from under the bench about an hour ago. I can see I'd already made new exhaust pistons. It's biggest problem was the nitrided steel sleeves. They kept distorting, so I made cast iron sleeves these worked but the rings were also cast iron ( weed eater ). At 14000 plus rpm the ring life was about 20 minutes. It needs nikasil or chrome barrels. I'm looking at what it would take to re make them now that I know how to cast twostroke cylinders. Also the ignition was a home made CDI and ALWAYS gave trouble. Now I would just fit two ignitec's.
What ever happened to that aluminium ? did it get used? I think I still have an ingot stored under the bench some where.

[husaberg]

Husaberg, here is a crude diagram of the uniflow concept, it gives you an idea at least.
I would say this is how the "Barker Headless" worked.

likely but it is the 4 carbs and 4 exhausts that intregue me with it. my last guess was a twin slit single on a common crank-pin like a Garelli

The Garelli is a real oddball split single. Most are tandem cylinders with either two rods or a forked rod. the garelli is side by side with a very long gudgeon pin. You're looking at the right hand cylinder which has the inlet ports at the bottom and two exhausts - one at the front of the cylinder and one at the back. No problems doing that as the transfers are all in the other cylinder.

So - sucks in on the right hand pot, transfers in the left hand one from a common crankcase , common combustion chamber , exhausts from the right hand pot as it's transferring fresh mix up the left barrel.....

Wob would approve of the long blowdown possible - and the uncontaminated fresh charge.

Frits - I see we overlapped - no factual differences which is pleasing - and no, I'm not old enough either.

<img src="http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=271859&d=1350297984" width="720px"/><img src="http://i1056.photobucket.com/albums/t380/uniflow/CCF06022013_00001_zps0f116803.jpg" width="270px"/>

PS if you click reply with quote you will see what i did with your pic:shifty:

[Flettner]

That's a very crude picture, you would probably want four carbs, one for each piston. And four exhausts would also be desirable. Yes I'm sure they use a single crank pin like the old split singles. It looks like just two split singles head to head, with a chain drive to join them. Almost as crude as my picture, is there any record of how it ran??

[koba]

http://i1056.photobucket.com/albums/t380/uniflow/CCF06022013_00001_zps0f116803.jpg

Husaberg, here is a crude diagram of the uniflow concept, it gives you an idea at least.
I would say this is how the "Barker Headless" worked.

Would it be better to have a hot side and a cool side?
Both exhausts on one crank and inlets on the other?

Would make heating and distortion more predictable, therefore manageable?

I'm not sure at all, it's just my first thought when I see that pic...

Edit: Nevermind, now I see the 'transfer?' port arrangement...

[TZ350]

Tests of Reverse Uniflow-Type Two-Stroke

Paper Number: 2004-32-0040

Abstract:
Conventional two-stroke engines have defects such as unstable combustion, high fuel consumption rate and high HC emissions. In order to overcome the defects, a direct fuel injection system and a novel scavenging system were adopted. The authors tested a newly developed reverse uniflow-type two-stroke direct injection gasoline engine that was designed by numerical simulations. In comparison with the base engine at low engine speed, HC emission was decreased by up to 80%, and BSFC was reduced by around 40%. Power and BSFC were superior to those of a latest port-injection four-stroke engine. Furthermore, it was found that engine performance of exhaust gas emissions, fuel economy or output power can be selectively optimized by switching homogeneous and stratified combustion.

[Flettner]

Mine has 6 degree crank out of phasing, exhaust piston ahead of the transfer piston. Helps with blow down time and gives the transfers a little more open time. The exhaust piston always gets the most thermal load, this is the feature that needs most attention, but certainly won't just melt as I was told it would .
Another useful feature is the the engine is rated as a twin, only two combustion chambers. Good for a twin cylinder class.
I'll get some pictures of the engine bits if anyone is interested?

[koba]

I'll get some pictures of the engine bits if anyone is interested?

I'm sure I speak for pleny more here when I say:

Yes!

Please.

[Yow Ling]

I'm sure I speak for pleny more here when I say:

Yes!

Please.

This vintage motorcycle stuff is causing quite a stir with the racers in the old peoples home

[Flettner]

What?? are we talking fuel injected F9?

[F5 Dave]

Crazy Man, yes, as it happens I've just got all the 100 uniflow bits out from under the bench about an hour ago. I can see I'd already made new exhaust pistons.. . .

Time to get it ready for the next Bucket GP. Promise it won't get a special award this time.:innocent:

nah seriously cool, just didn't have a camera in those days.

[wobbly]

Allah or God save us - the Uniflow Psychos have infiltrated the thread.
HELLLLPPP, we need the team that took out Osama to do a night raid on the terrorist training ground in Eureka.
I can point to the location on Google Maps to make it easyer.
BE VERY AFRAID.

[Grumph]

Allah or God save us - the Uniflow Psychos have infiltrated the thread.
HELLLLPPP, we need the team that took out Osama to do a night raid on the terrorist training ground in Eureka.
I can point to the location on Google Maps to make it easyer.
BE VERY AFRAID.

I agree 100%....but we of the old folks home have another target. However it's proving hard to come up with enough ready cash to get a taxi to the Yow Ling residence....

[crazy man]

Crazy Man, yes, as it happens I've just got all the 100 uniflow bits out from under the bench about an hour ago. I can see I'd already made new exhaust pistons. It's biggest problem was the nitrided steel sleeves. They kept distorting, so I made cast iron sleeves these worked but the rings were also cast iron ( weed eater ). At 14000 plus rpm the ring life was about 20 minutes. It needs nikasil or chrome barrels. I'm looking at what it would take to re make them now that I know how to cast twostroke cylinders. Also the ignition was a home made CDI and ALWAYS gave trouble. Now I would just fit two ignitec's.
What ever happened to that aluminium ? did it get used? I think I still have an ingot stored under the bench some wherethe aluminium is still under the bench still waiting for a project maybe the 3 clinder 100 me and brent are having a go at .l had the 100 water cooled twin the day you brought your uniflow out . remember you saying your 100 went good in a gokart and then somthing was going wrong when you put it in your bike . looked cool though

[Flettner]

http://i1056.photobucket.com/albums/t380/uniflow/DSCF5108_zpsdcb0ea4b.jpg
http://i1056.photobucket.com/albums/t380/uniflow/DSCF5109_zps49c43a63.jpghttp://i1056.photobucket.com/albums/t380/uniflow/DSCF5111_zpsa685cb45.jpghttp://i1056.photobucket.com/albums/t380/uniflow/DSCF5112_zpsd53e47b5.jpg
Yes it was that bloody home made ignition, it had two units running four plugs. It needed both to keep the advance to a reasonable number, one unit would spark in atmosphere but not under pressure! It was working properly in the go kart but on the change over to the bike it was damaged and it took months to finally find the problem. Just like being very retarded ( because it was ) I was over it by then! http://i1056.photobucket.com/albums/t380/uniflow/DSCF5113_zps92006150.jpg
Here's looking down the barrel of a 440.

[cotswold]

Been back to ESE head quarters this evening to balance my crankshaft. TeeZee set me up with some scales, some welding wire and a pile of washers. First up the rod, piston, pin and small end were weighed giving us a total of, I think 232gms, TZ works on the 50% theory so the wire and washers were weighed accordingly and hung off the end of the rod, this was then placed on the very technical looking balancing device where it was found to be PBC, the fly wheel was drilled in four places to get the correct balance.
Before all this we put it in the lathe and using a dial gauge we checked that it was running true, not too bad just a light tap with the truing device and we were happy.
Thanks to Tee Zee and Culley for their time.

[speedpro]

If that last picture is the finished product it "looks" like it's balanced for about 2-3,000rpm. That's a lot of counterbalance. I would not be surprised if it vibrates like crazy from 5 up.

Actually the crankwheels aren't relieved inside much except right at the big end pin so probably not as bad as I first thought.

[Frits Overmars]

First up the rod, piston, pin and small end were weighed giving us a total of, I think 232gms, TZ works on the 50% theory so the wire and washers were weighed accordingly and hung off the end of the rod, this was then placed on the very technical looking balancing device where it was found to be PBC, the fly wheel was drilled in four places to get the correct balance.Let me start by complimenting you on a very clear description plus illustration of the balancing act. But you should not have drilled those holes where you did. As a rule of thumb, a good press fit requires that a big end pin hole should be surrounded by at least half its diameter in material. So for a 20 mm pin there should be at least 10 mm of crank web material everywhere around the hole. As you can see, the large original balancing holes already intrude into this zone, and with the small holes you added there will be little stiffness left.
Removing material in the blue circles would have been a safer approach, although it might not haved raised the balance factor sufficiently.
The best way would be to remove material from the inside faces of the crank webs, around the big end recesses. That would have two additional benefits: it would improve lubrication and cooling of the big end bearing and it would enlarge the crankcase volume.
Now that I am grumbling anyway: big end pins should be massive. The large void in the pictured pin is not exactly promoting a good press fit.

[SwePatrick]

Tig weld the pin carfully to the crank, keeps the crank from twisting and the pin will most certenly stay in place,,, for ever ;)

A very common mod on dragracebikes and snowmobiledragsters.
And make sure you have enough axial play at the big end of the rod before welding.
Do NOT go for the tight fit,, rather do a 'sloppy' one.
Keeps it from seizing at high revs.

Rgds.

[FastFred]

you should not have drilled those holes where you did. As a rule of thumb, a good press fit requires that a big end pin hole should be surrounded by at least half its diameter in material. So for a 20 mm pin there should be at least 10 mm of crank web material everywhere around the hole. As you can see, the large original balancing holes already intrude into this zone

No doubt you have to work with what you have.

Maybe the pin could have expander plugs fitted like you see in the KT100 go cart engine to lock it in place.

A slug of Mallory Metal or Tungsten could be pressed into the flywheel opposite the big end pin instead of having to drill the extra balance holes so close to the pin.

[FastFred]

That's a lot of counterbalance. I would not be surprised if it vibrates like crazy from 5 up.

I had a look at the scales, BF 50% more or less.

[Yow Ling]

In a moment of weakness I bought this cvt scooter, ticks a few boxes, cvt , 125 aircooled, $50, oozes style, lacks handling, just need to sneak it home

278126

[F5 Dave]

Yeees! The Honda Lead. With the vagaries of the English language I assume they were intending it to be pronounced as the verb 'to lead'

. . .rather than the base metal, which is far funnier.

[Grumph]

In a moment of weakness I bought this cvt scooter, ticks a few boxes, cvt , 125 aircooled, $50, oozes style, lacks handling, just need to sneak it home

278126

I'll expect to see Brendon on it at Methven....you know you want to.....

[F5 Dave]

Tell me he hasn't Chernobyl'd that 150 I picked up for him already

[Flettner]

More uniflow 100 pictures, drive side.

http://i1056.photobucket.com/albums/t380/uniflow/DSCF5114_zps3d8a30ec.jpg

New 650 engine castings,

http://i1056.photobucket.com/albums/t380/uniflow/DSCF5115_zpsbba1b95d.jpg

[TZ350]

Thats interesting stuff, I am very impressed with the castings.

[cotswold]

A bit of home work Tee Zee had me doing

[TZ350]

They look really good, hopefully they will help stop some of the heat in the cylinder from conducting to the crankcase.

[wobbly]

Just so people get a handle on the reality of my situation re the F3 bikes.
One customer whos engine had done over 50 full noise dyno tests, took the bike to Taupo.
There it did 4 - 20 minute sessions as hard as it would go, bad front end issues, no brakes, and wrong gearing.
Max egt 1235 with 195/198 mains.
Pull the barrel and the pistons look like new - see the pic..
Now it has done another full day at Manfield with super rich jetting to try and nail the handling.No problems, needs attention at trailing part throttle, mid corner.
But in a straight line you " hang on for grim death ".

The other customer ran the bike for the first time with the same jetting, at sea level, after being told to go up to at least 210, and not exceed 1250 - the red lights ( 4 of them ) come on at 1260.
He didnt, do as advised.
First fast session it hit 1350 with all the lights flashing like crazy.
Carried on for 5 more laps till it siezed on part throttle.
I have never in 30 years seen an engine survive over 1300 F, ever.
Piston to bore is now over twice what it should be - surprise , surprise.
Now im told Wossner pistons are shit - the plating is shit - and by inference I couldnt tune my way out of a brown paper bag.
Am I angry - yes.
Easy to fix - yes.

[Sketchy_Racer]

Just so people get a handle on the reality of my situation re the F3 bikes.
One customer whos engine had done over 50 full noise dyno tests, took the bike to Taupo.
There it did 4 - 20 minute sessions as hard as it would go, bad front end issues, no brakes, and wrong gearing.
Max egt 1235 with 195/198 mains.
Pull the barrel and the pistons look like new - see the pic..
Now it has done another full day at Manfield with super rich jetting to try and nail the handling.No problems, needs attention at trailing part throttle, mid corner.
But in a straight line you " hang on for grim death ".

The other customer ran the bike for the first time with the same jetting, at sea level, after being told to go up to at least 210, and not exceed 1250 - the red lights ( 4 of them ) come on at 1260.
He didnt, do as advised.
First fast session it hit 1350 with all the lights flashing like crazy.
Carried on for 5 more laps till it siezed on part throttle.
I have never in 30 years seen an engine survive over 1300 F, ever.
Piston to bore is now over twice what it should be - surprise , surprise.
Now im told Wossner pistons are shit - the plating is shit - and by inference I couldnt tune my way out of a brown paper bag.
Am I angry - yes.
Easy to fix - yes.

Might need to put in a anti retard cutout when EGT's go to high, what a pillock.

When are we going to see someone pilot one of these in F3. The Ozzy450 I rode in 2008 was awesome fun and set lap records at manfeild and puke but I'd say the power vs weight of your weapons would be a serious contender.

[Flettner]

I see the EFI CR500 featured in Dirt Rider Downunder is sporting a carburetor now. What happened?
I thought we were looking at the future.

[husaberg]

Seems the only info HGT gives out is "...........for 31yrs I was a GM engineer..........."

BRC (make Rotax 256 copy kart engines) Riley Will (who contributed to the pitlane.biz RSA thread) spoke the most sense there


The 2002 500cc bikes used 35-36mm carbs with electronic solenoid type power jets.

KTM used a hybrid system where they used an injector to augment the fueling requirements. It was used in their 250cc program, but I'm not 100% sure if they used it in the 125cc bike as well. Probably, but I cannot be certain.

Aprilia was guilty of throwing out what they perfected (carburation)and introducing a totally new concept loaded with technology EFI system. It was an intelligent system that made all the theoretical calculations at light speed..... It was a perfect system....... Too perfect! For years 2 stroke engine development was being done using less than perfect carburetor. This includes rider knowledge, tire construction, and suspension..... The end result was that the riders and machinery (tires) couldn't cope with the instantaneous increase in torque when the throttle was opened while at maximum lean angles.

When I discussed how I was going to do my EFI, their main electronics engineer started clapping..... What I wanted to do (and later did) was to upload a fuel distribution curve similar to a Del'Lorto needle/tube (needle jet) combination and did not let the computer adjust it. I used a TPS, H2O sensor, Air temp sensor, and Hall Sensor for crank angle/rpm. This way I was using what I knew, but getting the benefit of 3 bar of fuel pressure and injector atomization. I had total control and could add fuel to make the fuel curve "imperfect" if need be. I used 2 injectors mounted on the engine side of the throttle valve and I alternated their firing so that I could rev upto 15000 rpm. That way each injector was mislead into thinking it was feeding a 7500 rpm max 4 stroke cylinder. In total I invested $1600 into the total system and had it running pulling load on the dyno in 3 hours.


Riley later says he timed the injector to squirt 10deg before inlet open and finish 10deg after inlet close


I have no airflow data, and once I have worked out how to post a few pictures I will. As was said they are a very clean carb for airflow with a flat slide. They do seem to self adjust for fueling as the air to fuel ratio's compared with the prior Mikuni powerjet reverse slides are similar. Once I have finished the setting up of the carbs I will give you more data, but that will be a few weeks yet.


since you are talking about injection... i was reluctant to post here but i thought it might interest someone else...

i just bought an injection kit from ecotrons, i took the cheap way, we'll see if this thing works. It is a cheap construction kit, but the fuel pump and injectors look good and the included program seems made by someone intelligent.
http://imageshack.us/photo/my-images/407/sdc12099copy.jpg/
http://imageshack.us/photo/my-images/847/sdc12098copy.jpg/

i am going to mill my own throttle body after a quick test with the one they sell.

my only purpouse is to try the 24/7 valve idea by Frits. that valve has a huge transition in the jet size requirement, due to the air flow becoming very slow when the valve is opened (working in 24/7 mode), a carb can not cope with this kind of transition.
this very cheap efi kit has a real-time switchable map, that can be used to switch between closed and open valve mode...

(Also, if Mr Overmars is reading: If you are going to join the Continental Championship Race Tech in some way, and you would use a cvt, i would be very glad to sponsor, i have a belt cvt patent with a lot improved efficiency that i would like to show you... won the italian scooter champ this year so it's something already tested extensively)


I noticed it is possible to simulate 24/7 with engmod2t, you just need to create a disk valve with 180 advance and 180 closing duration. 360° disk=24/7
Engmod is particularly efficient because it keeps a trace of every wave travelling here and there.

You can also play around a lot with crankcase volume, inlet lenght and diameter and see how much a 24/7 is sensitive to these params (an looks very sensitive of course). I played with exhaust pipes also, and looks like a conventional pipe works good, in fact the only way you could modify a pipe would be to thin the power range (and try to make more powerful pulses) but this way pays too much in term of usable range, with little or no gain at top...
also I think that with 24/7 you would like a very broad and long pulse to keep the air as much as possible into the engine, without coming back out from the intake.


Hé Nasone, cosa stai facendo su questo forum?
A friend of mine, Martijn Stehouwer (twice european champion classic 50 cc racing in 2009 and 2010) is planning to build a 50 cc racer with CVT transmission for the CCRT series, so we are very interested in your belt. You can get in touch with him via info@emot.nl or via a private message in Pit-Lane.biz.

Regarding the exhaust pipe: the 24/7 system requires nothing out of the ordinary. A pipe that functions well on a 'normal' engine, will do just as well in combination with the 24/7-system, once it is running in the power band.
Like you said: the transition from reed induction to 24/7 may cause carburation problems, and the logical way out is fuel injection.


I too would be very interested in this transmission. please PM me.


You can't expect the carburation of a reed bike to remain perfect after the reed breaks, Dave; it will probably have a lot of blow-back and therefore a terribly rich mixture. You'd need to find the right combination of crankcase volume (large!), inlet tract diameter and length for a clean 24/7-carburation.
Which complicated reedblock are you talking about? The one with the two hinged reeds coupled by gears that you may have seen in www.pit-lane.biz (http://www.pit-lane.biz)?
That was the very first prototype, over ten years old now. It was over-engineered all right; just one hinged reed without any gears will do just fine.

What you are suggesting, two carbs, has been tried by a dutch Kreidler tuner: http://kreidler.nl/forum/viewtopic.php?f=5&t=38866 .
He didn't even bother with guillotines or reeds; just the normal piston-ported carb and a second carb connected directly to the crankcase.
In the video the jetting is off and he opens that second throttle way too early but nevertheless the contraption runs....


254941

Made an adjustable PJ out of a model aero engine carb needle jet for controlling the PJ. Now to get one of those solenoids the Husaburg posted to shut off the PJ for a bit of extra over rev.

Made some progress with the shorter inlet tract and expect to get the lower mid range back again with a bit of fiddling with the carburation.

Just a little bit more and the single exhaust port engine with the RS pipe will be very close to EngMod2T's predicted power output.

254940 125cc rotary valve with a 24mm carb and air cooled.

Measured 31 rwhp (estimated 34 crank hp) on the dyno tonight, red line is last night before the inlet tract was shortened and the jetting/ignition adjusted.

I have ordered one of Wobblys special kitset "A" Kit Pipes for a Suzuki GP125 ..... so hopefully 1 or 2 more hp and a wider spread of power. Then there is the ATAC idea for better low end.


Re the tiny bleed hole in the TZ powerjet tube - I always thought that this was a good idea to emulsify the fuel as it exited the dropper.
But years ago i did some wet tests on the flowbench with a VCR video camera ( pretty trick shit stuff back then ).
The Mikuni was a horror scene when played back slo mo,with huge "gobbs" of fuel exiting the main and powerjet.
We then stuck on a Lectron - wow, lovely fine mist of fuel from the back of the flat needle face - and it flowed 12% more air - size for size with a venturi 2mm smaller behind the slide.

Next is the current state of TeeZees GP125, here is the latest dyno curve digitised with 16% added to simulate crank power.
Then there is the sim with an actual RS early model pipe.
Then there is the new pipe of my design.
Of most interest is that in this case the sim is giving slightly too much crank power - but the shape and peak point are all but perfect.
I would be confident now that any change in the sim, would be reflected in reality on the dyno.
In my experience the later Dynojets like a twin roller 168 with Eddy current load control to slow the acceleration rate down ,seem to read around 5 to 10% lower
so this would put the sim and the dyno reading very close, as the shape is spot on now.


When using a simple powerjet nozzle the tip position matters in that no flow will occur until the slide is well past the exit hole, and there is sufficient airflow
to drag fuel up the feed tube above the bowl level.
With the aftermarket add ons and the ones as used by Lectron you can shorten the dump tube so that the flow will only occur at high slide openings,as well as high air flow.
These also have a built in "lag "control in that it takes time for the fuel to rise up the tube and dump out the exit into the air stream.
With a solenoid controlled setup all this is pretty much irrelevant as the flow can only occur when the solenoid is not powered up, and this
is TPS as well as rpm dependant inside the ECU program..
The carbs as used on the MX bikes has the dump tube very low in the bore as they added and subtracted fuel at low slide positions in those bikes.
For a race engine I bend the tube up to around 1/2 bore, as this is where the exit is on the Kehin SPJ carb for RS125/RS250 Honda.
And the general setting is the solenoid is powered up ie no flow below 4000 and 60% TPS and is powered up again at around 12400 to lean off the mixture and increase revon.
This causes a problem with Ignitechs that are used with only a capacitor, as at startup the solenoid is powered up, dragging all the voltage out of the ECU, so I convert the ECU output
to a 3 step truth table, and have the setting such that below 1500rpm the solenoid isnt powered.


The tube is thick walled and bends easily by simply levering it up.
You can take it out, but then when its bent it wont go back in,as its designed to be pushed in from the outside.
Here is the table


Gentlemen, I'd just like to poke my nose in here and say that I've been lurking in this thread for quite some time and it just keeps getting better and better. By far the most informative thread I've found on 2 stroke design. Thanks to all and keep at it. As a guy who plays with 2 strokes as a (very expensive) hobby, I really appreciate everything openly posted here. The fellow who rides the race RZs I build thanks you too.


LOL. Fair enough Frits, thats some perspective. Expensive is relative of course. In the last couple of months I've bought a TD2 project bike, a TZR250 for one of my projects and more parts and services bike related than my marriage could stand were it openly discussed.
In the spirit of the co-operation already in this thread, and considering that fuel injection was brought up earlier, here is the beginning of a prototype system I've been playing with. I'd appreciate any feedback, hopefully productive. If you'd like to say it won't work that's fine but please explain why?

http://i48.photobucket.com/albums/f224/cookie1965/pfi2.jpg

http://i48.photobucket.com/albums/f224/cookie1965/pfi4.jpg

Now some of you may recognize my name as a member of another forum where FI has been discussed,(I recognize some of your usernames), and may hold against me some things I said there. Please understand that my comments there were made because of my frustration with a poster there and his apparent arrogance and unwillingness to share information. Don't misunderstand me, I don't believe that it was required of him, but rather than refuse to answer questions he acted as though the questions were somehow beneath him. I would appreciate it if these pics didn't appear elsewhere. I'd rather it be running before I face the firestorm. Thanks.

edit. I really don't know why those pics are so small...sorry

Anything well just about anything can be made to work given enough time, money and more importantly determination.

I concept is great but why one throttle body?
What is the outcome you are after drivablity, fuel consumption,Tune-ability, emissions or performance. ?
The main issues i see is that carbs are light and simple and relatively specking. Ie no battery/alternator, fuel pump regulator ECU etc.
I am not knocking you because it is great to actually do it rather than just thing about it or just ruling it out.
What sort of fuel pressure are you envisaging?
I remember the Cagiva system involved huge pressures.
The biggest potential advantages i see with fuel injection are economy and emissions drive-ability but maybe, i am short sighted about this.

The one thing i did pick up from a few pages back was the split system with each set of injectors handling half the revolutions. So two injectors on each cylinder running each fueling alternate revolutions. Which should solve a few of the problems with doing it in the past.

You could also maybe alter the characteristics under overrun even possibly dial in some engine braking.
Maybe include a four stroke switch for slippery conditions and learner racers.

2011 Return of the two stroke. Possibly premature.
http://www.youtube.com/watch?v=goNP9pLHhyU&lc=rwsGLtvui8s1Pt4dgQ7L18qW3Iqbnn2MaWTHlcr08SQ&context=C3714f15ADOEgsToPDskL7BjBrQhia1uTNqMht_TCF



I see the EFI CR500 featured in Dirt Rider Downunder is sporting a carburetor now. What happened?
I thought we were looking at the future.

A collection of stuff i found interesting

Buried in there Neil is the Post regarding the Aprilia Fuel injection This could be out of context as i don't remember the origional quote?

Riley Will make the Super karts contributes to Pitlane makes closed ended Gudgeons as well the part prices for the Superkarts seem quite reasonable to but what was his background......http://www.brceng.com/250fe.html
http://www.brceng.com/images/new250.gif
Re the CTV did it come to anything Frits and ROB?

oh and speaking of CR500s and the future where is my jetpack...


"If I had thought about it, I wouldn't have done the experiment. The literature was full of examples that said you can't do this." --Spencer Silver on the work that led to the unique adhesives for 3-M "Post-It" Notepads

[dinamik2t]

When using a powerjet ... With a solenoid controlled setup ...
And the general setting is the solenoid is powered up ie no flow below 4000 and 60% TPS and is powered up again at around 12400 to lean off the mixture and increase revon.

Wob, could you post aproper AFR/ADV map incorporating the powerjet shut-off function -if it's not "business" info?

I remember a post of yours, saying afr would go from 12 to 14, so I tried the 13.5~14 value.
I tried setting it up like this:

278403

Shutting it off at 12500, from 12 to 13.5Afr. Tuned length 860mm and 198° ex.
I can't get it to make any difference in overrev (from leaving it at 12Afr all the way).. Both times, engine RPM stop at 13000, with just a little more power with the PJ.

On the other hand, I tried finding the 'shut-off' AFR from the jet sizes. Area of MJ+PJ=Fuel-Air ratio.
2.55mm² (MJ 180) + 0.2mm² (PJ 50) = 0.083 (12AFR)
2.55mm² = x (1/x AFR)
This gives a ~13 AFR (reasonable?). I don't know if that's a good simplification though...

[TZ350]

Re the CTV did it come to anything Frits ROB?

CVT ... I am still working on mine. I am building a completely new lighter bike that has more of its weight on the front wheel and two engine setups for it, one conventional and the other will have a CVT transmission. It seems to take forever to get anywhere.

[Frits Overmars]

It seems to take forever to get anywhere.Tell me about it. Luckily it will probably not affect the speed of the end product :rolleyes:.

[Grumph]

Just so people get a handle on the reality of my situation re the F3 bikes.
One customer whos engine had done over 50 full noise dyno tests, took the bike to Taupo.
There it did 4 - 20 minute sessions as hard as it would go, bad front end issues, no brakes, and wrong gearing.
Max egt 1235 with 195/198 mains.
Pull the barrel and the pistons look like new - see the pic..
Now it has done another full day at Manfield with super rich jetting to try and nail the handling.No problems, needs attention at trailing part throttle, mid corner.
But in a straight line you " hang on for grim death ".

The other customer ran the bike for the first time with the same jetting, at sea level, after being told to go up to at least 210, and not exceed 1250 - the red lights ( 4 of them ) come on at 1260.
He didnt, do as advised.
First fast session it hit 1350 with all the lights flashing like crazy.
Carried on for 5 more laps till it siezed on part throttle.
I have never in 30 years seen an engine survive over 1300 F, ever.
Piston to bore is now over twice what it should be - surprise , surprise.
Now im told Wossner pistons are shit - the plating is shit - and by inference I couldnt tune my way out of a brown paper bag.
Am I angry - yes.
Easy to fix - yes.

Every one of us who has built motors for money has horror stories like this...."Picking customers" should be a required course for engine builders. I find a simple question "will you do what I tell you ?" and observation of the body language helps a lot....

[husaberg]

CVT ... I am still working on mine. I am building a completely new lighter bike that has more of its weight on the front wheel and two engine setups for it, one conventional and the other will have a CVT transmission. It seems to take forever to get anywhere.

I was meaning of the contact with Frits and yo with nasone32?

[wobbly]

The problem as I see it with adjusting the AFR trying to simulate a PJ being switched off is that this has two effects on the result.
It will increase the temp seen by the pipe, but I believe also the code does a calculation of the energy available in the fuel, and adjusts the power
that quantity will deliver - maybe in this case the two counteract each other exactly.
This is because max power is seen down at a rich mixture,around 12:1, closer to stoichiometric there is less power available, in theory and reality.

But the other thing you should realise is that although a solenoid powerjet is reducing the fuel delivered to the engine, it
is actually correcting the natural,progressively richening mixture coming from the carb, not reducing the AFR below what is was previously.

I will ask Neels about a workaround, but my reaction would be to use the pipe wall temp/rpm input screen,to increase the average temp in the pipe after a set rpm.
Going from a " normal " 50* wall temp to a 150* wall temp at 12,000 will for sure have the desired effect on the overev.
In reality the temp will increase gradually, so a temp ramp over say 1000rpm would simulate reality better.
I dont know if the code interpolates temp between the set points.

[F5 Dave]

Just so people get a handle on the reality of my situation re the F3 bikes.
One customer whos engine had done over 50 full noise dyno tests, took the bike to Taupo.
There it did 4 - 20 minute sessions as hard as it would go, bad front end issues, no brakes, and wrong gearing.
Max egt 1235 with 195/198 mains.
Pull the barrel and the pistons look like new - see the pic..
Now it has done another full day at Manfield with super rich jetting to try and nail the handling.No problems, needs attention at trailing part throttle, mid corner.
But in a straight line you " hang on for grim death ".

The other customer ran the bike for the first time with the same jetting, at sea level, after being told to go up to at least 210, and not exceed 1250 - the red lights ( 4 of them ) come on at 1260.
He didnt, do as advised.
First fast session it hit 1350 with all the lights flashing like crazy.
Carried on for 5 more laps till it siezed on part throttle.
I have never in 30 years seen an engine survive over 1300 F, ever.
Piston to bore is now over twice what it should be - surprise , surprise.
Now im told Wossner pistons are shit - the plating is shit - and by inference I couldnt tune my way out of a brown paper bag.
Am I angry - yes.
Easy to fix - yes.

A mate had to deal with same sort of thing (erm 10yrs ago), he was sending his RS barrel over to (I won't name) a UK RS125 specialist & doubled up with another racer to save on postage, both got some porting & a replate.

Well the other guy's bike seized next time he rode it & all my mate heard was this guy is rubbish blah blah. I've heard the same story about several other prominent names as well but I figure that that is part & parcel of the buss.

But what is interesting is the amount you've cut the rear transfer feed back in the RZ cases.

[wobbly]

What you find with cylinder reeds on an engine like the RZ is that as you approach 100CHp the inlet STA becomes the limiting factor.
The pistons have huge holes in them ( a Blaster basic design ) and it has two big boost ports up the back, as well as big elongated
Boyesen ports down the sides.
To get the 100 Hp it needed more intake, so dropping the Boyesens even more needed bigger cutouts into the case.
Thus pulling back the case transfer duct rear edge very close to the stud, gave easy access for the flow thru the Boyesesn bottom edge into the case.
I dont like the idea of cutting away the rear wall of the rear transfer, to get inlet flow area, as this flow is at right angles to the flow thru the duct - to the port.
It may work fine - but doesnt seem intuitively "right ".

[dinamik2t]

Good idea the one with wall temp, I will try it.
Thanks for the assistance Wob!

(I believe there is no need to tell you 'well done', you would know your capabilities better than anyone, but it's very encouraging to hear from a happy customer at least :rockon:)

[F5 Dave]

What you find with cylinder reeds on an engine like the RZ is that as you approach 100CHp the inlet STA becomes the limiting factor.
The pistons have huge holes in them ( a Blaster basic design ) and it has two big boost ports up the back, as well as big elongated
Boyesen ports down the sides.
To get the 100 Hp it needed more intake, so dropping the Boyesens even more needed bigger cutouts into the case.
Thus pulling back the case transfer duct rear edge very close to the stud, gave easy access for the flow thru the Boyesesn bottom edge into the case.
I dont like the idea of cutting away the rear wall of the rear transfer, to get inlet flow area, as this flow is at right angles to the flow thru the duct - to the port.
It may work fine - but doesnt seem intuitively "right ".

Ahh yes, had to look at pick of my 496 barrels, thanks for explaination.

[wobbly]

Yea, so here are the two options to increase inlet flow.
I believe the case entry is more effective.
But who knows, maybe both will make more power together.

[Flettner]

Yes Wobbly I've got customers like that too! They just won't listen, you just know they are going to crash their gyro. Usually they do. Good business on the rebuilds though.

[wax]

LOL. Fair enough Frits, thats some perspective. Expensive is relative of course. In the last couple of months I've bought a TD2 project bike, a TZR250 for one of my projects and more parts and services bike related than my marriage could stand were it openly discussed.
In the spirit of the co-operation already in this thread, and considering that fuel injection was brought up earlier, here is the beginning of a prototype system I've been playing with. I'd appreciate any feedback, hopefully productive. If you'd like to say it won't work that's fine but please explain why?

http://i48.photobucket.com/albums/f224/cookie1965/pfi2.jpg

http://i48.photobucket.com/albums/f224/cookie1965/pfi4.jpg

Now some of you may recognize my name as a member of another forum where FI has been discussed,(I recognize some of your usernames), and may hold against me some things I said there. Please understand that my comments there were made because of my frustration with a poster there and his apparent arrogance and unwillingness to share information. Don't misunderstand me, I don't believe that it was required of him, but rather than refuse to answer questions he acted as though the questions were somehow beneath him. I would appreciate it if these pics didn't appear elsewhere. I'd rather it be running before I face the firestorm. Thanks.

edit. I really don't know why those pics are so small...sorry
I know the twat you are talking about. He doesn't do them any more as it turns out he was just rebadging ectrons anyway. And no one could get them to run. Not so much of a high gain there in the long run

[F5 Dave]

Yea, so here are the two options to increase inlet flow.
I believe the case entry is more effective.
But who knows, maybe both will make more power together.
You can almost see the shiny mark to follow on the barrel.

Before I found this pic I was imagining you may have been moving the rear of the C transfer back further still which I thought was ambitious but interested to see if it was a target (not that I want to develop my 496 any, its hard enough to get it roadworthy with the time I have anyway). PS the bypass thermo & rad modifications seem to have done the trick lowering operating temp on a decent roadride.

[cookie1965]

I know the twat you are talking about. He doesn't do them any more as it turns out he was just rebadging ectrons anyway. And no one could get them to run. Not so much of a high gain there in the long run

Yeah that's the guy. I haven't seen him in a long time but in the past you could find him by responding to one of his threads there, I guess he has auto notifications and can't help himself but reply to anything and everything.
I've put the PFI on the backburner again, built new pipes and did some porting getting my old RZ ready for this season, working on a stroked YPVS motor in a TZR chassis, building a dyno and just picked up a loaner Ape RS125 to get ready to race this season too. Busy.

[wax]

I was there as well till they banned me for exposing him lol Iluvtwostroke was my name
He doesnt do them anymore anyway he found it to hard and decided that it as no good. after telling every one how good it was and if you disagreed you were just misinformed. He mainly sticks to the aprillia forum now where is a moderator and he simply bans you if you disagree
I am banned

[teriks]

Something from the modeling world that might be of interest, even though it's a bit dated.

Sources:
http://www.go-cl.se/castor.html
http://modelenginenews.org/faq/index.html#qa5



CASTOR OIL
By Bert Striegler.
Rescued from George M. Aldrich's web site, now closed down, after his passing away. Some edits and additions by Göran Olsson.

Back in 1983 there was quite a controversy in Radio Control Modeler magazine about the tests that were necessary to measure the "lubricity" of various oils that might be useful in model engines. Castor oil was used as the benchmark, but it was obvious no one knew why this was so. They apparently got a lot of info on various industry tests of lubricants, but these were really designed for other purposes. This was my answer. I will remind you that I was a lubrication engineer and not a chemist, but I drew my chemical info from Bob Durr, the most experienced lubricant scientist in the labs at Conoco. Bob worked with my group on many product development projects and I can tell you that he is one smart hombre! Small changes were made in the text, but surprisingly very little has really changed since this was originally written. Here goes with the answer:

"I thought I would answer your plea for more information on castor oil and its "film strength", which can be a very misleading term. I have never really seen a satisfactory way to measure the film strength of an oil like castor oil. We routinely use tests like the Falex test, the Timken test or the Shell 4-ball test, but these are primarily designed to measure the effect of chemical extreme pressure agents such as are used in gear oils. These "EP" agents have no function in an IC engine, particularly the two-stroke model engine types.

You really have to go back to the basics of lubrication to get a better handle on what happens in a model engine. For any fluid to act as a lubricant, it must first be "polar" enough to wet the moving surfaces. Next, it must have a high resistance to surface boiling and vaporization at the temperatures encountered. Ideally the fluid should have "oiliness", which is difficult to measure but generally requires a rather large molecular structure. Even water can be a good lubricant under the right conditions.

Castor oil meets these rather simple requirements in an engine, with only one really severe drawback in that it is thermally unstable. This unusual instability is the thing that lets castor oil lubricate at temperatures well beyond those at which most synthetics will work. Castor oil is roughly 87% triglyceride of ricinoleic acid, [ (CH3(CH2)5CH(OH)CH2CH=CH(CH2)7COO)3(OC)3H5 ], which is unique because there is a double bond in the 9th position and a hydroxyl in the 11th position. As the temperature goes up, it loses one molecule of water and becomes a "drying" oil. Another look at the molecule. Castor oil has excellent storage stability at room temperatures, but it polymerizes rapidly as the temperature goes up. As it polymerizes, it forms ever-heavier "oils" that are rich in esters. These esters do not even begin to decompose until the temperature hits about 650 degrees F (343 deg C). Castor oil forms huge molecular structures at these elevated temperatures - in other words, as the temperature goes up, the castor oil exposed to these temperatures responds by becoming an even better lubricant!

Unfortunately, the end byproduct of this process is what we refer to as "varnish." So, you can't have everything, but you can come close by running a mixture of castor oil with polyalkylene glycol like Union Carbide's UCON, or their MA 731. This mixture has some synergistic properties, or better properties than either product had alone. As an interesting sidelight, castor oil can be stabilized to a degree by the addition of Vitamin E (Tocopherol) in small quantities, but if you make it too stable it would no longer offer the unusual high temperature protection that it did before.

Castor oil is not normally soluble in ordinary petroleum oils, but if you polymerize it for several hours at 300 degrees F (149 deg C), the polymerized oil becomes soluble. Hydrogenation achieves somewhat the same effect.

Castor oil has other unique properties. It is highly polar and has a great affinity for metal surfaces. It has a flash point of only 445 degrees F (229 deg C), but its fire point is about 840 degrees F (449 deg C)! This is very unusual behavior if you consider that polyalkylene glycols flash at about 350-400 degrees F (176-204 deg C)and have a fire point of only about 550 degrees F (288 deg C), or slightly higher. Nearly all of the common synthetics that we use burn in the combustion chamber if you get off too lean. Castor oil does not, because it is busily forming more and more complex polymers as the temperature goes up. Most synthetics boil on the cylinder walls at temperatures slightly above their flash point. The same activity can take place in the wrist pin area, depending on engine design.

Synthetics also have another interesting feature - they would like to return to the materials from which they were made, usually things like ethylene oxide, complex alcohols, or other less suitable lubricants. This happens very rapidly when a critical temperature is reached. We call this phenomena "unzippering" for obvious reasons. So, you have a choice. Run the engine too lean and it gets too hot. The synthetic burns or simply vaporizes, but castor oil decomposes into a soft varnish and a series of ester groups that still have powerful lubricity. Good reason for a mix of the two lubricants!

In spite of all this, the synthetics are still excellent lubricants if you know their limitations and work within those limits. Used properly, engine life will be good with either product. Cooked on a lean run, castor oil will win every time. A mix of the two can give the best of both worlds. Most glo engines can get by with only a little castor oil in the oil mix, but diesels, with their higher cooling loads and heavier wrist pin pressures, thrive on more castor oil in the mix.

Like most things in this old life, lubricants are always a compromise of good and bad properties. We can and do get away with murder in our glo engines because they are "alcohol cooled" to a large degree. Diesels, though, can really stress the synthetics we use today and do better with a generous amount of castor oil in the lubricant mix. Synthetics yield a clean engine, while castor oil yields a dirty engine, but at least now you know why! "

Bert Striegler

Bert was the Sr. Research Eng'r. (ret.) at Conoco Oil Co. He's a graduate in aeronautical eng'rg., and a long time modeler. I never understood how he wound up in the oil research business, but I guess it's because he's just very smart ! I deserve no credit, Bert's the brain ! /George M. Aldrich

A bit redundant, but some additional pieces here:


Question:

Should I replace castor oil with modern synthetic oil?
Answer:

Tricky question, and not one I'm in any way qualified to answer. There's a lot of folk-lore and ju-ju thrown about on this topic. Instead of poking my vulnerable neck out, here's some words of real wisdom on castor from the master: Bert Striegler. Read it and decide for yourself!

Back in 1983 there was quite a controversy in Radio Control Modeller magazine about the tests that were necessary to measure the "lubricity" of various oils that might be useful in model engines. Castor oil was used as the benchmark, but it was obvious no one knew why this was so. They apparently got a lot of info on various industry tests of lubricants, but these were really designed for other purposes. This was my answer. I will remind you that I was a lubrication engineer and not a chemist, but I drew my chemical info from Bob Durr, the most experienced lubricant scientist in the labs at Conoco. Bob worked with my group on many product development projects and I can tell you that he is one smart hombre! Small changes were made in the text, but surprisingly very little has really changed since this was originally written. Here goes with the answer:

"I thought I would answer your plea for more information on castor oil and its "film strength", which can be a very misleading term. I have never really seen a satisfactory way to measure the film strength of an oil like castor oil. We routinely use tests like the Falex test, the Timken test or the Shell 4-ball test, but these are primarily designed to measure the effect of chemical extreme pressure agents such as are used in gear oils. These "EP" agents have no function in an IC engine, particularly the two-stroke model engine types.

You really have to go back to the basics of lubrication to get a better handle on what happens in a model engine. For any fluid to act as a lubricant, it must first be "polar" enough to wet the moving surfaces. Next, it must have a high resistance to surface boiling and vaporization at the temperatures encountered. Ideally the fluid should have "oiliness", which is difficult to measure but generally requires a rather large molecular structure. Even water can be a good lubricant under the right conditions.

Castor oil meets these rather simple requirements in an engine, with only one really severe drawback in that it is thermally unstable. This unusual instability is the thing that lets castor oil lubricate at temperatures well beyond those at which most synthetics will work. Castor oil is roughly 87% triglyceride ricinoleic acid, which is unique because there is a double bond in the 9th position and a hydroxyl in the 11th position. As the temperature goes up, it loses one molecule of water and becomes a "drying" oil. Castor oil has excellent storage stability at room temperatures, but it polymerizes rapidly as the temperature goes up. As it polymerizes, it forms ever-heavier "oils" that are rich in esters. These esters do not even begin to decompose until the temperature hits about 650 degrees F. Castor oil forms huge molecular structures at these elevated temperatures - in other words, as the temperature goes up, the castor oil exposed to these temperatures responds by becoming an even better lubricant!

Unfortunately, the end by-product of this process is what we refer to as "varnish." So, you can't have everything, but you can come close by running a mixture of castor oil with polyalkylene glycol like Union Carbide's UCON, or their MA 731. This mixture has some synergistic properties, or better properties than either product had alone. As an interesting sidelight, castor oil can be stabilized to a degree by the addition of Vitamin E (Tocopherol) in small quantities, but if you make it too stable it would no longer offer the unusual high temperature protection that it did before.

Castor oil is not normally soluble in ordinary petroleum oils, but if you polymerize it for several hours at 300 degrees F, the polymerized oil becomes soluble. Hydrogenation achieves somewhat the same effect.

Castor oil has other unique properties. It is highly polar and has a great affinity for metal surfaces. It has a flash point of only 445 degrees F, but its fire point is about 840 degrees F! This is very unusual behavior if you consider that polyalkylene glycols flash at about 350-400 degrees F and have a fire point of only about 550 degrees F, or slightly higher. Nearly all of the common synthetics that we use burn in the combustion chamber if you get off too lean. Castor oil does not, because it is busily forming more and more complex polymers as the temperature goes up. Most synthetics boil on the cylinder walls at temperatures slightly above their flash point. The same activity can take place in the wrist pin area, depending on engine design.

Synthetics also have another interesting feature - they would like to return to the materials from which they were made, usually things like ethylene oxide, complex alcohols, or other less suitable lubricants. This happens very rapidly when a critical temperature is reached. We call this phenomena "unzippering" for obvious reasons. So, you have a choice. Run the engine too lean and it gets too hot. The synthetic burns or simply vaporizes, but castor oil decomposes into a soft varnish and a series of ester groups that still have powerful lubricity. Good reason for a mix of the two lubricants!

In spite of all this, the synthetics are still excellent lubricants if you know their limitations and work within those limits. Used properly, engine life will be good with either product. Cooked on a lean run, castor oil will win every time. A mix of the two can give the best of both worlds. Most glow engines can get by with only a little castor oil in the oil mix, but diesels, with their higher cooling loads and heavier wrist pin pressures, thrive on more castor oil in the mix.

Like most things in this old life, lubricants are always a compromise of good and bad properties. We can and do get away with murder in our glow engines because they are "alcohol cooled" to a large degree. Diesels, though, can really stress the synthetics we use today and do better with a generous amount of castor oil in the lubricant mix. Synthetics yield a clean engine, while castor oil yields a dirty engine, but at least now you know why!"

But wait! There's more (Bert again):

I have been thinking for a while about how to answer your seemingly simple question, "What is the flash and fire points of SAE 70 motor oil?". I was always told that engineers are people who can make something complicated out of something simple, and that is what I am going to have to do!

First of all, there is not now and has never been such a product as an SAE 70 oil. The SAE grading system used to stop at 60, and for all practical purposes, is now limited to 50. It is an arbitrary system based on the viscosity of lighter oils at 0 Degrees F. and heavier oils at 210 degrees F. The reasoning was that 0 degrees was about as low as you could expect to be able to start an engine, and 210 degrees was about as hot as you expected the oil to get in a crankcase. This scale was produced years ago, and today we routinely start gasoline engines at temps of -40 degrees F, and some of our crankcase oil testing is done in engines at oil temps of 330 degrees F and higher.

We used to make Conoco 70 oil, and it was basically a blend of bright stock and a little bit of 800 pale oil. These are the two products I will use as an example of why I cannot answer your question straightforwardly. Oil base stocks are usually produced in a vacuum distillation tower after all the lighter ends of the crudes are driven off. This is a process carried out under a 2MM vacuum. Our 5295 bright stock first starts boiling off in this tower at about 500F. 5% is boiled off at 560, 20% at 600, and finally 50% at 650, at which point the oil begins to "crack" into lighter and heavier products. The point is that, unlike synthetics, we are dealing here with a product that boils off in varying degrees in a range of temperatures from roughly 500F to 650F and then cracks. 800 pale oil is a lighter product which starts boiling at about 375F and finally starts cracking at about 630F. From the distillation curve, I would estimate the flash of bright stock at about 560 and 800 pale at about 475F. A blend of the two would flash closer to the 800 pale number that to the bright stock number. Different folks made 70 oils in different blending fashion, so no two brands would yield the same flash or fire points. We never used "dumbbell" blends at Conoco. By that I mean a blend of very heavy oil and very light oil to get a medium oil viscosity. We used to see a lot of this type blending and it is not good.

With petroleum oils, the fire point is usually 60 to 80 F above the flash point, very close to the cracking temperature. What does all this mean? Practically nothing, because in practice we don't usually reach these kind of temperatures EXCEPT where the oil is mixed into the fuels. Oil carried into the combustion chamber can be exposed to cracking temperatures. Have you ever had a really black exhaust with an ignition engine using petroleum oil lubes? I have, and it is even more common in diesels. What that tells you is that the oil is cracking, that burning of the oil is incomplete and the black is plain ole carbon. So, petroleum oil is a little bit like castor in that it comes apart over a wide range of temperature. Synthetics, on the other hand, boil, flash and then burn in a very narrow range but when they do burn, they normally burn completely with a clear and clean exhaust. That's why they leave less oil on the airplane.

Everything I just told you is in regards to paraffinic base oils, but there are also naphthenic base oils around. They produce less carbon, have a lower wax content and thin out more quickly with a rise in temperature than the paraffinic stocks. Naphthenic stocks are preferred in large gas engines and other operations that are sensitive to carbon buildup over a long period of time, but these stocks are more sensitive to oxidation and have a lower flash and fire point. Paraffinic oils are better lubricants in most operations. Paraffinic oils used to be called "bright" oils or "green" oils because in sunlight, a clear bottle filled with paraffinic oil had a bright green "bloom" when looked at with the light coming through it. Naphthenic stocks have a pale blue "bloom" and used to be sold as cheap engine oils in years past. I don't think a naphthenic based motor oil would be able to pass our modern engine tests and they are rarely seen anymore.

In a nutshell, you are not really going to burn a 70 oil in the combustion chamber and flash and fire points are a non-issue. I quit using 70 oils a long time ago because of the carbon problem. Modern outboard motor oils are SAE 40 oils with ashless additives and are diluted 20% with a high grade kerosene to assure easy mixing. One of the tests that they have to pass is a wide-open throttle test in a 100 HP outboard pulling about 60HP on the dyno using a 300 to 1 mix of the diluted oil in gasoline! This is a 100 hour test, or was when I was involved. The engines looked really good and all parts were measured before and after the testing was done. That is not a mistake, 300/1! Some of these oils are synthetic, blends with synthetic and petroleum oils, and straight petroleum oils. All have an elaborate, ashless additive system.

For our purposes, castor is still the best. The heavier petroleum oils share a wide distillation range so they offer some lean run protection like castor. The synthetics perform well in our engines unless you reach their boiling point, at which point you are dead meat. A good rule of thumb is "The messier the airplane, the better the lube is working." There is really nothing wrong with burning the synthetics in the combustion chamber. The only caution is that if the engine gets off too hot and the cylinder walls reach the boiling point of the lube, then all is lost. That is not likely to ever happen with petroleum or castor oils in the SAE 40 range of viscosity.

[F5 Dave]

Makes me feel a little better about this weekend's experiment to drown my engine in R30 in an attempt to get some decent ring seal that has bean eluding me. (excuse the pun:rolleyes:)

[wobbly]

Done a heap of dyno work on this for KT100, where 1/10ths of Hp are valuable.
Short story is the testing proved what was being said above.
The modern full synthetic race oils were designed for unleaded as used in FIM since 1998.
Best example is Elf 976.
Unleaded makes best power with no com, high advance and running rich - perfect for the synthetic.
Avgas or leaded race gas is dead opposite, the hotter the better.
In the tests the synthetic made alot less power when run lean ( as the KTs do to make them rev past 16,000 )
and made no more power at 16:1 than 30:1
Semi synthetic works best in the situations where high temps are seen
Maxima 927 Elf 909 Motul Kart etc all made more power the more oil added.
The oldest and the one that made marginally the best power was partial bean oil Castrol A747.

[husaberg]

Done a heap of dyno work on this for KT100, where 1/10ths of Hp are valuable.
Short story is the testing proved what was being said above.
The modern full synthetic race oils were designed for unleaded as used in FIM since 1998.
Best example is Elf 976.
Unleaded makes best power with no com, high advance and running rich - perfect for the synthetic.
Avgas or leaded race gas is dead opposite, the hotter the better.
In the tests the synthetic made alot less power when run lean ( as the KTs do to make them rev past 16,000 )
and made no more power at 16:1 than 30:1
Semi synthetic works best in the situations where high temps are seen
Maxima 927 Elf 909 Motul Kart etc all made more power the more oil added.
The oldest and the one that made marginally the best power was partial bean oil Castrol A747.

Makes me feel a little better about this weekend's experiment to drown my engine in R30 in an attempt to get some decent ring seal that has bean eluding me. (excuse the pun:rolleyes:)

Other people would have a better handle on this but i seem to remember sealing issues with the Britten i think they in the end had to do a complete change the liner material so the sponsor’s oil (Mobil 1) would work. I seem to remember it wasn't an issue with the same materials and the non-sponsors oil.</SPAN>
People often moan about castor gumming stuff up but i have never found it an issue, IMO if you are getting gumming you really need to take a good look at your maintenance intervals.

[F5 Dave]

PVs are a game changer for clean running, but not on most buckets.

I've run Motul 800 for years & had good results in the 50.
I used to run Golden Spectro in the H100 & although it reved less the wear was astronomically minimal. But since I decided the MB100 would rev further I would run same 30:1 800 for both 50 & 100 (in Av). Introduce the KT parts into the MB engine & I get ring seal/bore polish issues.

Either my bore is unstable & can't hold still despite a few attempts reboring/honing. Or it just isn't running-in that combination of materials & 800.

I've bought a ring leak tester so hopefully with a couple of careful load variation practise sessions & a days racing on R30 15:1 (& unleaded so it will mix) I'll see an improvement & can switch back to Av & 800 (after using the R30 up to be sure).

[kel]

I've bought a ring leak tester so hopefully with a couple of careful load variation practise sessions & a days racing on R30 15:1 (& unleaded so it will mix) I'll see an improvement & can switch back to Av & 800 (after using the R30 up to be sure).

Dumb question time but why are trying to run your motor in on synthetics and/or castor? Surely mineral oil should be used for bedding in the rings?

A question for the experts -
I was planing on running my new motor in on the dyno. I figure a couple of minutes at moderately high revs then a single flat out run then dump the fuel and mineral oil mix and switch to kart oil (synthetic castor mix). I realise this is a fairly agressive approach but is it an acceptable way of running in a race motor?

[wobbly]

That used to be a good idea on the old synthetics.
But bean oil and the new semi synthetics have no trouble bedding rings etc during a short run in period.
But its just as much a matter of getting heat cycles into the piston, as it is about surface bedding, so 10 minutes of hard accelerations,up and down the gears,without hard reving is the go.

In my testing Elf 909 was the best all round, it looked like a run in on castor, with NO scratching of the new piston, and made good power - almost the same as A747
no matter how lean you were.
Motul 800 was crap when up at 650* EGT, so was the trick shit Elf 976.

[F5 Dave]

Thanks yeah I've never had any issue before, so I'm re assessing.


. . .
Motul 800 was crap when up at 650* EGT, so was the trick shit Elf 976.
Sorry I don't understand that statement.

[wobbly]

As the big shpeal about castor was basically saying - pure synthetic "oils " are shit at lubricating anything when the combustion temps are thru the roof ie 650*C in the header.
This is the perfectly normal situation on pump gas with the air cooled KT100, and perfectly normal when running AvGas in a properly tuned race engine of any sort.
In my KT100 dyno tests I had resolution down at 1/10s of a Hp, with a rigorous test procedure that had every run with EXACTLY the same case and head temp at the
beginning of each run, ( probes on the case and under the plug - logged continuously ) combined with EXACTLY the same egt in the pipe at run end.

The pure synthetics made a HEAP less power when running lean at 650* C , the worst dropping 1.5 Hp in 18.
Adding more oil made NO difference - still shit.
You MAY not seize the thing, but for sure you are making nowhere near the power potential of the engine when run that way.

The bean oil derivatives were completely the opposite, run hot and no loss of power, run more oil = more power, every time.
Understand THAT.

Like I said - pure synthetics are fine when run with unleaded at conservative combustion temps - abuse them and everything turns to shit - real fast.

[kel]

In my testing Elf 909 was the best all round,
Thanks Wobbly. Just so happens we are using Elf 909 (something to do with "Wob says its the trick shit" ;)). I've been told 30:1 is a good ratio in the water cooled 50's, would I increase the oil ratio for an air cooled motor on avgas? I understand more oil = more hp as per your post above but I was hoping theres an acceptable ratio that wont empty the wallet too quickly.

[Yow Ling]

As the big shpeal about castor was basically saying - pure synthetic "oils " are shit at lubricating anything when the combustion temps are thru the roof ie 650*C in the header.
This is the perfectly normal situation on pump gas with the air cooled KT100, and perfectly normal when running AvGas in a properly tuned race engine of any sort.
In my KT100 dyno tests I had resolution down at 1/10s of a Hp, with a rigorous test procedure that had every run with EXACTLY the same case and head temp at the
beginning of each run, ( probes on the case and under the plug - logged continuously ) combined with EXACTLY the same egt in the pipe at run end.

The pure synthetics made a HEAP less power when running lean at 650* C , the worst dropping 1.5 Hp in 18.
Adding more oil made NO difference - still shit.
You MAY not seize the thing, but for sure you are making nowhere near the power potential of the engine when run that way.

The bean oil derivatives were completely the opposite, run hot and no loss of power, run more oil = more power, every time.
Understand THAT.

Like I said - pure synthetics are fine when run with unleaded at conservative combustion temps - abuse them and everything turns to shit - real fast.

Thanks Wob that sorts out the oil. Now about the fuel

seeing as unleaded runs with a particular set of conditions and Avgas runs runs with different conditions, is there a blend of avgas and unleaded that provides the best of both worlds like a faster burning fuel that is not prone to detonation. Are there any gains to be made here in either helping with engine durability or additional power from extra com etc. People have been doing this since time began , is there any scientifically backed or dyno proven testing on this?
thanks

[teriks]

run more oil = more power, every time.
My stuff must make ridiculous amounts of power then, running on 20% castor, remainder methanol :-P

Joking aside, really interesting to hear of your experiences confirming theory Wob!

I can confirm Berts statement about getting away with murder in the methanol fueled, castor lubricated model engines.
I have on too many occasions molten the Platinum/Rhodium glow plug wire, holed a few pistons and even had the edge of the squish band rounded by melting on one occasion. I never had the piston seize though.

[Ocean1]

Now about the fuel

90% nitromethane / 10% methanol works quite well at about 65psi...

[cookie1965]

I was there as well till they banned me for exposing him lol Iluvtwostroke was my name
He doesnt do them anymore anyway he found it to hard and decided that it as no good. after telling every one how good it was and if you disagreed you were just misinformed. He mainly sticks to the aprillia forum now where is a moderator and he simply bans you if you disagree
I am banned

Oh yeah I remember you from over there LOL. So he's quit altogether trying to sell his PFI set up? For everything? I looked at his site just now and don't see any reference to it.

[wobbly]

This is only conjecture on my part as I have never done a back to back with two optimised setups.
But,I fail to see how lowering the octane rating of AvGas by diluting it with pump gas, would somehow be offset by a figment of manys imagination that flame speed has suddenly increased.
Yes I know, AvGas has a pile of shit added to prevent icing at altitude, but it jets, and reacts to detonation exactly the same as 105 octane VP leaded race gas as used by SKUSA.
I tested a 1US Gallon tin of it that cost over 200nzd to fly here on a special dangerous goods flight.
When the squish is optimised, as is the com, and the ignition,Avgas makes a heap more power than unleaded.
Flame speed doesnt appear to be an issue - it works.
Unleaded hates compression, needs alot more advance ( why would it if the flame speed was faster? ) and has to be run rich to make best power.
The two fuels need wildly different conditions to work best - a nightmare to try and sort out - not worth the brain damage in my opinion.

Re the oils - in the KT100 air cooled the best power on bean oil is had at 16:1.
Running 909 as most Yamaha karters do now, going below 20:1 gave a minimal advantage - on the dyno at least.
Some say that 16 "works better" but thats, again, probably a figment.
Bottom line is that if you are tuned hard out in your air cooled bucket, then 20:1 will be about as good as it gets.
As always though there is a down side - 909 wont stay mixed with AvGas for long.
You have to add a small amount of Acetone to ensure mixing, its fine in pump gas to leave for weeks, but you wouldnt do that would you.

[wax]

Oh yeah I remember you from over there LOL. So he's quit altogether trying to sell his PFI set up? For everything? I looked at his site just now and don't see any reference to it.

If you go the aprillia forum he says he can get just as much power out of a ditech engine as he can a pfi and in the end it was not worth it. the ditech is one of the slowest things around. If you see him smartmouthing again just ask him how much power his turbo scooter made I think it was 8hp.

[F5 Dave]

As the big shpeal about castor was basically saying - pure synthetic "oils " are shit at lubricating anything when the combustion temps are thru the roof ie 650*C in the header.
This is the perfectly normal situation on pump gas with the air cooled KT100, and perfectly normal when running AvGas in a properly tuned race engine of any sort.
. . ..
Thanks ok that is interesting to say the least.

When we are talking Bean oil are you only saying castor like R30? or using A747?

I had intended to use R30 for a couple of meets & swap back to 800, but its sounding like I should wait until I watercool the barrel/head, but I was waiting till I got the sealing problem sorted before progressing. &or swap to Elf.

But to use Av & R30 I'd have to use Acetone & the rules don't seem to mention it anymore.

[wobbly]

Today I would include all the semi synthetic and castor based oils in the term - bean oil.
Now we have these trick mixes available, running straight R30 is no advantage in power and for sure film strength, havnt seen it for ages, is it cheap??
The good new ones like 909,Kart, Maxima etc sure arent.

[F5 Dave]

yeah I found it in super cheap for $29.95 a l.

Wiped over my pipe nice.

So if I mix it with Av I'm asking for trouble? I have some 95 pump gas I was going to use.

[Yow Ling]

So if I mix it with Av I'm asking for trouble? .

You that good?

[breezy]

this may still be relevent and worth a lookat http://www.klemmvintage.com/oils.htm

[TZ350]

this may still be relevent and worth a lookat http://www.klemmvintage.com/oils.htm

278587

Thanks Breezy, that is a very good read.

[RMS eng]

yeah I found it in super cheap for $29.95 a l.

Wiped over my pipe nice.

So if I mix it with Av I'm asking for trouble? I have some 95 pump gas I was going to use.

this topic has been on here before,but just to put my 2 cents in i run R30 in my air cooled vintage MX 125 bikes on Av and pump with 5% acetone,and it is fine,AV gas is the safe way to go.Dave i can sell you R30 for $66.00 for 3 bottles 1LT or $122.00 for a box of 6.

chris RMS engineering 09 817 9500

[rgvbaz]

Click image for larger version. Name: BigCrankBluevisSmallCrankRed.jpg Views: 25 Size: 207.2 KB ID: 277890

"The Red line is the smaller crank with 2mm clearance. I am not sure why the improvement is all at the bottom end and drops of earlier at the top.
Helmholtz frequency, my dear Watson. The smaller crank will give the pipe more crankcase volume to breathe from. This larger volume will also lower the resonance frequency of the inlet system, hence the drop at high rpm. It can be compensated with a shorter inlet tract, a bigger carb diameter and a later inlet closure. To put it real simple: if you have more volume, you need more time to fill it. But more time, i.e. later closure, has adverse effects at low revs. So my preference is a shorter tract (unless you go the 24/7-way and employ a reed for the low revs, and swing it out of the way at high revs)."

This is a Quote from Frits on page 710

I was playing with a reed spacer on an AM6 engine. In the graph below run 44 and 45 are with just the reed. Runs 48 and 49 are with a 46*40*8mm spacer between the crankcase and the reed which changes the crank case volume by about 15cc. But the peak rpm goes the other way? Am I missing something obvious?

278590

Dave

[husaberg]

mr overmars Here's some more Helmholtz-encouragement:

Regarding induction systems: build a short induction tract and visit a test bench.
You can forget about calculations. The formulas you find in various books are all based on the Helmholtz resonator. It made me write a simple story, called:


Helmholtz blues
"A Helmholtz resonator consists of a volume connected to a duct". That is what Wikipedia tries to tell you.
But that is a Helmholtz resonator in its simplest form; one that you won't find anywhere in an engine.
What you do find in an engine is an intake tract with a variable cross-sectional area. This tract is from time to time connected to a variable volume (the crankcase) through a very variable window (the intake port / reed valve / rotary inlet).
The crankcase is connected to a number of transfer ducts with variable cross-sectional areas, which are from time to time connected to a very variable volume (the cylinder) through a number of very variable windows (the transfer ports).
The cylinder is from time to time, through a very variable window (the exhaust port), connected to an exhaust pipe with a very variable cross-sectional area who at the same time doubles as a volume. This pipe volume is constantly connected to a big volume (the outside world) through a tailpipe with a constant cross-sectional area and constant entry and exit windows (thank God, finally someting that's not variable).
We call this a compound Helmholtz resonator .
The various papers also tell us how to calculate the resonator's frequency:
" frequency = speed of sound / (2*pi)* Sqr ( cross-sectional area of the neck / ( volume of the resonator * effective neck length ) ) ".
O yes, the speed of sound... It is dependent on temperature, which is not really constant in the intake tract and the crankcase, rather variable in the transfer ducts and very variable in the cylinder and the exhaust pipe.
Now the above frequency formula is not exact; it is an approximation that is usable as long as the volume of 'the' tract is very small compared to the resonator's volume.
So when engines are concerned, that formula goes very far out the window.
Who said gas dynamics is simple dull?
PS:
It's a similar story with acoustics. That is a sub-branch of gas dynamics, simplified with a lot of assumptions that are acceptable as long as the sound pressure does not exceed a certain limit. The wave pressures in a two-stoke exhaust exceed that limit by a factor of thousand. Bye bye, acoustics...

Wouldn't also your spacer also as well as increasing the volume make the track longer also......................
In fact it throws up a huge amount of variables shape of tract shrouding of reeds etc. Aren't two strokes a cruel mistress

[Frits Overmars]

I was playing with a reed spacer on an AM6 engine. In the graph below run 44 and 45 are with just the reed. Runs 48 and 49 are with a 46*40*8mm spacer between the crankcase and the reed which changes the crank case volume by about 15cc. But the peak rpm goes the other way? Am I missing something obvious?Increasing the crankcase volume has several consequences. One of those is that the flow through the carb will be more even, less violent, which usually results in a leaner mixture. Looking at your curves that would seem to be the most probable explanation. Did you fiddle with the jetting as well as with the spacer?

[wobbly]

The instant you make the case vol bigger the jetting goes richer, and visa versa.
If you had a egt trace on the screen I would bet the runs with the spacer were lower egt, that is what has moved the peak Hp point.

In a Rotax 257 single designed for road racing, I filled the crank holes and machined the reed box off 10mm.
This was to use it on a kart sprint track, the jetting was 10 sizes different for the same 1250* egt, no other changes.

[ief]

Something seems amiss here... contradicting posts.

higher egt = peak higher up the rev range right?

edit: wrong then? :)

[wobbly]

The blue run is reed only,then with the spacer fitted the green run is to the left = lower egt from bigger case.

[rgvbaz]

The blue run is reed only,then with the spacer fitted the green run is to the left = lower egt from bigger case.

Wayne, other way around. Spacer gave the higher peak RPM.

Dave

[rgvbaz]

Increasing the crankcase volume has several consequences. One of those is that the flow through the carb will be more even, less violent, which usually results in a leaner mixture. Looking at your curves that would seem to be the most probable explanation. Did you fiddle with the jetting as well as with the spacer?

Yes, obvious now you say it Frits, but I never would have thought about that!

No I didn't play with the jetting:( I realise now I should have!

Dave

[rgvbaz]

Wouldn't also your spacer also as well as increasing the volume make the track longer also......................
In fact it throws up a huge amount of variables shape of tract shrouding of reeds etc. Aren't two strokes a cruel mistress

Yes, they are female!

[wobbly]

Yes and I am a dumb shit - the spacer raised the rpm, so the bigger case gave more rpm but no more power.
If the egt had been tracked then a rejet may have cranked out some more power as well.
Must be loosing it, sorry.

[richban]

Yes and I am a dumb shit - the spacer raised the rpm, so the bigger case gave more rpm but no more power.
If the egt had been tracked then a rejet may have cranked out some more power as well.
Must be loosing it, sorry.


Well I must say you got it right with the 400. Was at manfield yesterday and man that thing is cool. It was flying at the end of the day. Smelt good sounded amazing and went like a f*cken rocket all day. Lots of people wanting one at the end of the day. Me included. weapon. I might have some video but I think I forgot to turn on the sound. bugger.

[wobbly]

Andy rang me and asked about a few jetting changes, sounds to have worked OK.
He seems to like " hanging on for grim death " in a straight line, as he calls it, but now it wheelstands off every turn.
Fuck I wish I could ride it, maybe bolt me on the back one day, like they did with the BSL500, and did 280 clicks at Puke to see if my daks turned brown.
My face was white and my knuckles were blue, but the seat was still green, just.

[richban]

Andy rang me and asked about a few jetting changes, sounds to have worked OK.
He seems to like " hanging on for grim death " in a straight line, as he calls it, but now it wheelstands off every turn.
Fuck I wish I could ride it, maybe bolt me on the back one day, like they did with the BSL500, and did 280 clicks at Puke to see if my daks turned brown.
My face was white and my knuckles were blue, but the seat was still green, just.



Yeah he mentioned wanting to smooth out the bottom. You could tell when he sorted it. Like you say wheel to the sky out of the turns. :niceone: Top end speed looked insane. Even compared to the 1L bikes around it. Not sure I would get on the back.