ESE's works engine tuner

[TZ350]

259365

The Wobbly Piranha is finished, we are keen to try it out on the dyno, but because the ignition map will need to be changed and that takes time, its maybe next week after Te Puke.

259366

A big thanks to Wobbly for his design and kitset pipe and Darren for his work putting it together, because without his help this would not have got finished. There is no way I could have done it myself, making a good job of pipes is a real art.

[Grumph]

Salvaging grooved shafts was indeed my main thought, any increase in seal life and/or reduced friction could be a side benefit.

Currently putting sleeves on the seal rubbing areas of an X7 road resto. Pretty common fix on those things.
The crank expert in ChCh - Barry Lynch, tends to hard chrome worn areas on race motors and grind, but sleeves road stuff. Horses for courses.

[Bert]

Look good TZ. looking forward to the dyno results.

or maybe not as it likely to have far more get up and go than mine...:weep:

[sonic_v]

259365

The Wobbly Piranha is finished, we are keen to try it out on the dyno, but because the ignition map will need to be changed and that takes time, its maybe next week after Te Puke.

259366

A big thanks to Wobbly for his design and kitset pipe and Darren for his work putting it together, because without his help this would not have got finished. There is no way I could have done it myself, making a good job of pipes is a real art.

I like to create my curves within the computer before I even go to the dyno, then it is possible to run through tests very quickly. Usually with a new pipe it can be very informative to run 3 or 4 straight line curves first as this can direct you to which curves to choose.

[TZ350]

Good idea, I will do that, I will set up some straights and good guess curves first. I have a good idea where things probably should be but just moved up the scale a bit. The good thing about the IgniTech is that the ignition curve can be re programed on the fly.

[breezy]

tz350,has this exhaust been designed to increase the power spread? you said you d hoped to get to around 4k usable power. noticed the belly setion has gone, is this the way to go now? does this pipe rely heavily on the ignition set up to work to its best? could this be the end of your excellent thread in pursuit of 30+rwhp suzuki gp125...i would sincerly hope not...:clap::beer:

[wobbly]

The pipe was designed to give a wider range but at a slightly higher rpm again.
This may in fact not be possible with the transfer geometry it has, and it may need to be lengthened a little to put it back in synch with the porting.
The timings are spot on, but for sure the scavenging regime isnt a RSA copy.
The belly starts at 66% of TL, but has 3 sections of bend within it - and another at the junction of the rear cone - that is why it looks that way, I was copying the centreline shape of a pressed pipe..
Every pipe is timing critical, this design is no more or less sensitive in that it will need the retard slope moving to the right if it forces the peak power up a few rpm.

[TZ350]

tz350,has this exhaust been designed to increase the power spread? you said you d hoped to get to around 4k usable power, could this be the end of your excellent thread in pursuit of 30+rwhp suzuki gp125...i would sincerly hope not...

No, :laugh: not the end yet, there are quite a few other people contributing interesting stuff to the thread and there is a way to go yet in developing this motor, both for max power and probably more importaintly, power spread.

The pipe should (hopfully) extend the top a bit and I hope a VTEC valve will plump up the bottom, then there are the 50's, and Wob is working on one for Giggles that will hopefully be 18 or so hp so plenty to do yet.

[Farmaken]

Will we see you at Te Puke TZ ??
Be nice to see the Wobbly Piranha feasting on fourstrokes !!:cool:

[TZ350]

Will we see you at Te Puke TZ ??
Be nice to see the Wobbly Piranha feasting on fourstrokes !!:cool:

Yes I will be at Te Puke as Kel's pit crew, but if its wet he may elect to run his FXR as trying out a new bike for the first time on a very tight wet slippery track might be a bit much.

But if its dry enough it would be good to get a few laps just to settle it in before the GP at Taupo.

I am looking forward to catching up with you when we get there, probably arrive mid morning Sat.

[koba]

Yes I will be at Te Puke as Kel's pit crew, but if its wet he may elect to run his FXR as trying out a new bike for the first time on a very tight wet slippery track might be a bit much.

But if its dry enough it would be good to get a few laps just to settle it in before the GP at Taupo.

I am looking forward to catching up with you when we get there, probably arrive mid morning Sat.

Cool, it will be good to see you there :)

I think it looks like a bit of a power track as far as kart tracks go, I always feel the disadvantage when pulling out of very slow corners and onto straights.

[husaberg]

TZ now has 30 or so HP a an impressive powerspread and he has achieved it but without a Electric PJ so far.
Will the expected performance gains in over rev potential (thus powerspread) you would expect from having one be hindered by the fact his carb is rather small (24mm because of the rules)
Also would the extra heat produced in the pipe from the high speed lean of effect his bike differently being air cooled. rather than being liquid cooled.

I also keep tripping over stuff done in the 70's and 60's that suggests something along the lines of a 10-20% greater power loss mid race compared to a liquid cooled as well.
Not that it matters, his engine still makes 30 HP more than mine does at the moment.:rolleyes:

Has anyone ever ran the bike on the dyno long enough to get an idea of the performance loss you would expect from a AC bike compared to a Liquid cooled.

On the subject of bearings and seals and so forth.
Something Dave said about if worse comes to worse with his need for a suitable little end bearing he would use a crowded set up. Wobbly said something about Bultaco days and i didn't twig, What he was meaning because something i never understood with Jennings writing that the Bultaco would last better at high revs if the little end was substituted for a crowded set up. Why? Were the standard cadged ones just crap?

One other bit i can remember reading something where someone claims the MV the little 125cc and 250cc ones race bikes had an odd big end that was uncrowded with two different diameter rollers bigger ones inside and smaller ones sort of between on the outer toward the outside of the rod.
I guess it would allow smaller diameter rollers anyone have any ideas on that?

[Yow Ling]

One other bit i can remember reading something where someone claims the MV the little 125cc and 250cc ones race bikes had an odd big end that was uncrowded with two different diameter rollers bigger ones inside and smaller ones sort of between on the outer toward the outside of the rod.
I guess it would allow smaller diameter rollers anyone have any ideas on that?

I cant imagine different diameter rollers, maybe different lengths. Any roller that was just a tiny cock smaller would carry no load, and the fat ones would be just greedy,

[bucketracer]

Has anyone ever ran the bike on the dyno long enough to get an idea of the performance loss you would expect from a AC bike compared to a Liquid cooled.

We have often done 10-15-20 runs at a time when setting up the ignitions with no more of a break between them than the time it takes to slow the dyno drum and there was no real power drop but we are expecting it will show up on the track, Taupo should tell more.

[husaberg]

I cant imagine different diameter rollers, maybe different lengths. Any roller that was just a tiny cock smaller would carry no load, and the fat ones would be just greedy,
I should draw a picture, but the larger ones and smaller ones both carry weight

[wobbly]

The solenoid Powerjet does lean off the BSFC curve BUT, what you need to get is that all it is doing is returning the fuelling to much closer to optimum.
Its not really "leaning it out "as such,it is dumping more of the available heat energy in the fuel - into the pipe, speeding up the wave action and thus extending overev available.
I dont think this engine has reached its thermal dissipation limit yet - as evidenced by the power not going away badly under load.
You know when you get there, as I did with KT100 pipe design project I did years ago.
As soon as the pipe produces more than 18Hp at the crank, the cylinder and head cannot get rid of the heat produced, and it will fade badly after 3 laps - hitting the thermal limit wall.
Needing fuel to cool it, not make power.
Thus I worked for months locked in a dyno room in Flat Bush extending the band width, at the expense of peak power.
It worked, as I have sold 2000 of the things in well over 10 years and they have won every Nationals title in that time.
I will slope over on Saturday to Te Puke, and poke a screwdriver in the spokes as a helping hand for you,

[F5 Dave]

Husi, when we were talking of crowded rollers Jennings was dealing with bikes running at sod all revs & presumably cages were pretty so-so back then. Wobblies opinion from memory was that at decent revs the rolers would rub against each other & with load that would cause skidding. It makes sense so I never went that way.

[husaberg]

Husi, when we were talking of crowded rollers Jennings was dealing with bikes running at sod all revs & presumably cages were pretty so-so back then. Wobblies opinion from memory was that at decent revs the rollers would rub against each other & with load that would cause skidding. It makes sense so I never went that way.
Yeah i with you with the crowded VS cadged (I raced old dungers remember) and some of them had no little end bearing either.
I do however understand it is not directly the speed that is the issue rather the variation in acceleration and deceleration that is issue. (YES I KNOW IT IS RELATED TO THE SPEED) The cadged roller bearing that Jennings suggests throwing, may have been a riveted or pressed design, rather than a solid design which i believe is superior. Of course the little ends don't suffer i believe to the same extent.
I understand at least one road bike had silver plated big ends or a least the manufacturer has superseded the original part number with one i also understand some bikes (TZ)at least had titanium cadges. I guess the silver plating may be to stop the work hardening of the Ti?
I would like some one expand a bit on the pro and cons of the other materials though.
I have seen a lot of talk about four strokes big ends failing on overrun which i guess is a result of the engine reaching higher revs due, i guess the engine being revs higher on overrun through the wheel speed driving the engine than it would reach on its own accord but that is just a theory mind you.

Below is a rather crude inaccurate rendering of what i had seen attributed to some early small MV race engines. Not to scale but it will express the design i guess.


Oh yeah Wob thanks for the explanation i wouldn't have guessed the KT100 only made that little power as well. So thanks.

oh yeah i found this as well maybe i should have read it again.

[Ocean1]

Up side of having no cage is that you get more rollers in the same space, giving you less load per roller, so the bearing can take higher loads. Down side is the rollers rub together at twice the speed of that against the inner or outer, so revs are usually limited.


The main function of a cage is to keep the rollers apart, but as important is to keep them parallel to the shaft. There has to be clearance between the inner and outer elements, without a cage the rolers are free to skew slightly until the roller ends touch the outer and the roller centre bridges across the middle of the inner. Even very small deviations from parallel impose extreme loads on the bearing, across very small surface areas. In fact the skew causes side load in inverse proportion to the angle, as the roller tries to "turn" sideways, effectively becoming a wedge. There are actually sprag (uni-directional) clutches that make use of this effect, they can lock a shaft up at very high torque, not a feature you really want in a gudgeon bearing.

[husaberg]

Up side of having no cage is that you get more rollers in the same space, giving you less load per roller, so the bearing can take higher loads. Down side is the rollers rub together at twice the speed of that against the inner or outer, so revs are usually limited.


The main function of a cage is to keep the rollers apart, but as important is to keep them parallel to the shaft. There has to be clearance between the inner and outer elements, without a cage the rolers are free to skew slightly until the roller ends touch the outer and the roller centre bridges across the middle of the inner. Even very small deviations from parallel impose extreme loads on the bearing, across very small surface areas. In fact the skew causes side load in inverse proportion to the angle, as the roller tries to "turn" sideways, effectively becoming a wedge. There are actually sprag (uni-directional) clutches that make use of this effect, they can lock a shaft up at very high torque, not a feature you really want in a gudgeon bearing.
Yeah if i remeber right the Vincent had small diameter half width crowded rollers 2 sets of short rollers with a divider in the middle i guess to stop the skewing.

Yeah the starters on 50 cc chinese crf50 have the set up as you desribe. I thought it was rather clever and i said that to a mate thats a Cat mechanic he wasn't impressed he said lots of starters have them.
I couldn't find the bit where jenning said to throw out the Bultaco cadged wrist pin bearing though.

[TZ350]

Entry list for the GP
http://pacificmccracing.wordpress.com/2012/03/07/nzsbk-championship-round-5-entries/

There looks like more than 30 Moto 4's (Buckets) lining up for the GP at Taupo, and F4 is looking like the biggest field, considering the entry fee I was not expecting so many of us would bother to make the trip.

I am glad so many have, and considering the names on the list, it should be an exciting meeting as its wide open, there are several potential winners this year.

[koba]

There looks like more than 30 Moto 4's (Buckets) lining up for the GP at Taupo, and F4 is looking like the biggest field, considering the entry fee I was not expecting so many of us would bother to make the trip.

I am glad so many have, and considering the names on the list, it should be an exciting meeting as its wide open, there are several potential winners this year.

I know, I'm gutted to have to miss it due to budgetary constraints.

[Yow Ling]

I hope they have the live streaming for the Moto 4's

Maybe now is the time to start asking for it, I think Jellywrestler on KB has something to do with it, Ill call him

[richban]

I hope they have the live streaming for the Moto 4's

Maybe now is the time to start asking for it, I think Jellywrestler on KB has something to do with it, Ill call him

What would be cool would be a guest commentator that knows a bit about the riders / class. TZ?

[wobbly]

On the over run with the gas closed - there is no combustion pressure on the piston, and this combined with riders that hook down thru the gears
when doing a corner entry, the extra rpm kills the bottom end.
This in effect doubles the cyclic peak load, at TDC and BDC as well.
Bartol said that they regularly saw 16,000 on a 125 when on trailing throttle, and this was killing the cages.
So they added an injector that was rpm and TPS driven, such that over a set rpm on trailing throttle it dumped fuel/oil into the case.


Where is the live streaming - someone got a link.
BTW - several Euro sports sites have live streaming of Moto GP, practice sessions and all.

[F5 Dave]

The ESE guys need to extend their GP entries to include the F5 bikes. Surely if entered in F4 they wouldn't late entry charge you. $70 for extra class, not the full $100.

Edit, hey hold on I don't see TZ or Greenie entered in F4 either?! (Pacific club website) How can you 'do-the-deed' on these mega buckets if you're not entered?? I see Ned & Av.

[TZ350]

The ESE guys need to extend their GP entries to include the F5 bikes.

The last 4-5 months have been very busy preparing specialist CNG equipment for export to China and India, and we can't do much more than field two bikes at the GP this year. Next year we expect to have at least three F5's or possibly five of them as there is a whole bunch in the pipe line, three RG50 based and two with RS chassis and 18 rwhp Aprila 50 engines.

[F5 Dave]

But one weekend & surely your & Greens bike are ready to ride?

I would say that might the RS50s in RS frames might spur me into fitting my Derbi engine. . . .but I've been saying that for, shit it must be 7 years & the engine has been finished for over 1/2 that. Next year, I keep saying. RG still battles on, but at least its out there.

[TZ350]

It isn't going to happen ....

[F5 Dave]

What? - you going to the GP, or me finishing the 50?

I keep having to sticky tape the 100 back together in between the dirtbike & trying to get some time to do the 500. I'll get to the 50 sooner or later. But then the roadbike needs maintenance, or some mod I've read about on the internet, heck the Trials bike occasionally needs attn. Must start that resto project I've been collecting parts for. . .

[TZ350]

What? - you going to the GP, or me finishing the 50?


Us taking 50's to this years GP, we just can't do it ...... sorry :weep:

[Yow Ling]

Where is the live streaming - someone got a link.
BTW - several Euro sports sites have live streaming of Moto GP, practice sessions and all.

Streaming was on NZSBK website, had live video with commentary , plus live timing , and live chat all on the same screen

[richban]

we can't do much more than field two bikes at the GP this year.

So reading between the lines. We have Avalon on a 30hp rs chassis bike and Ned on pretty much the same. Well all I can say is bugger! Could be the year boys.

[ac3_snow]

... Could be the year boys.

Sure hope so, would be well deserved with all the work they have put in!!

[TZ350]

So reading between the lines. We have Avalon on a 30hp rs chassis bike and Ned on pretty much the same. Well all I can say is bugger! Could be the year boys.

Av's is only 25 rwhp and Kel is on my 30hp Beast but 30hp only leaves Kel with the same power to weight ratio as Av and Av's got the better chassis.

Dave M will be peddling Speedpro's 30hp FZR/MB100

So it looks like some real compitition this year.

[Yow Ling]

Got word back from Spyda/ Jellywrestler re commentary

"as for buckets F4 if it's there we commentate and can't see any reason the live streaming won't cover it, biggest thing we need is commentator info so will be up there earlier in the weekend to get as much as i can
yep saw nick do the deed at levels all those little bike classes have good racing too, it's somethinbg i'm focussing on more these days
cheers
spyda "

If you guys can help with a little background about the current bucket scene it would make the commentary all the better.

Personally Im over the "Bucket of Shit" mentality that comes with uninformed commentators, Spyda is up with the present and does a great job but needs good info to promote our sport.

Cheers
Yow

[richban]

Av's is only 25 rwhp and Kel is on my 30hp Beast but 30hp only leaves Kel with the same power to weight ratio as Av and Av's got the better chassis.

Dave M will be peddling Speedpro's 30hp FZR/MB100

So it looks like some real compitition this year.

Bloody Bloody Bloody. I had a feeling that team Shanny would be there, new and improved. Well my new engine is still underway. I finished the manifold today. By total fluke it is .3 mm longer than perfect. New forged piston is machined and ready. Just waiting on the crank. Needs rebalancing coz the piston is a lump. New cams new valves new everything really. Looking at reving it to 14. We will see. Bring your cement bags.:rolleyes:

[kel]

Dave M will be peddling Speedpro's 30hp FZR/MB100

Ooh didnt see that one coming.
Taupo is going to be very interesting, all going well one of us (The Daves all 3 of them, Nathanel, Avalon Rick or myself) will put the 4 strokes in their place, but it sure wont be easy with so much talent on show! I'd hate to have to call the top 10 it really could go any way.
How lucky am I to land a ride on the the beast :2thumbsup

[kel]

What would be cool would be a guest commentator that knows a bit about the riders / class. TZ?

Agreed. The ESE crew chief would be a fine choice.

[richban]

How lucky am I to land a ride on the the beast :2thumbsup

Yep I want to book a ride on that thing. Maybe on a kart track. That would be just stupid good.

[kel]

Yep I want to book a ride on that thing.

Dont know about that, I'll be looking to renew my contract:lol:

[speedpro]

1st place should sort that. Shame really :Pokey:

[marsheng]

I'm finally getting the hang of some of the tuning pieces on carbs. However this part has still eluding me. It is an OKO 30 mm. I have got the idle jet correct, a good needle with clip in the correct position and the main jet seems ok. It starts idles and runs well below 2/3 throttle but nearing full throttle, (the bike still pulling well) I get a nice thick mist at the carb mouth above 9500 through to 13000

It has an emulsion tube and from what I have read, above 2/3 throttle, the holes in the tube lean the mixture off to ensure the correct balance. My guess is there is so much fuel being drawn out that it is not really vapourising well and floating all over the place. As some of it is being drawn into the engine as droplets, the bike still runs well as the air/fuel in vapour is the correct ratio. The main jet is already quite small.

I'm asking as drilling extra holes in the emulsion tube or increasing the air bleed holes (drilling the carb out) will improve the vapourisaton of the fuel but it is one of those jobs where it is difficult to return back to original if required.

Any suggestions ?

[speedpro]

Any suggestions ?

It's fine, leave it alone. All you are seeing is the mixture that was rushing into the engine bouncing back out because the intake has closed. Most of it gets sucked back in on the next cycle

[Frits Overmars]

It's fine, leave it alone. All you are seeing is the mixture that was rushing into the engine bouncing back out because the intake has closed. Most of it gets sucked back in on the next cycle:niceone:. If you really want to know, try retarding the intake closure. And get a spare emulsion tube if you intend to alter the present one :cool:.

[Yow Ling]

Marsheng failed to mention its a 4 stroke

[marsheng]

Marsheng failed to mention its a 4 stroke

I tried this carb a year ago I could not get it to work properly. Interestingly, the guy who I bought this from, also could not get it to work. It is basically a new high performance carb. I've got a bit more knowledge now and giving it another go and have got better results but still not good enough.

http://www.marshland.co.nz/ftp/CB150/CarbInners.JPG

I stripped the unit and I noticed that the air bleed jet is very small, about 0.8 mm which would 'confirm' that the fuel is not getting enough air to correctly emulsify.

[Yow Ling]

OK Im only posting this here because this is the only thread on kb most people read

Sorry its a diesel, but it is out there so worth a look

http://www.simplicitymotorworks.com/Documents/Rotary%20Piston%20ICE%20-%20Its%20Features.pdf

has a disk valve and several departures from normal

maybe this better link

http://www.simplicitymotorworks.com/

[richban]

I stripped the unit and I noticed that the air bleed jet is very small, about 0.8 mm which would 'confirm' that the fuel is not getting enough air to correctly emulsify.

There was a thread on a pit bike site in AU that talked about fixing really crapy PWK knock offs. With my 30 and 32 I drilled it to 1mm. Manly because the castings were a bit wrong. Is this a power jet version? When I get my FCR working I could lend you my 32 it should be jetted and very close to what you need. Little rich on the bottom but hey just keep it pinned.

[wobbly]

I checked the emulsion air passage on a pile of different 2T type Keihin carbs when I converted a 4T FCR downdraft to work on a 2T.
They ranged from 1.7 to 1.9 mm - none were jets as such ,just drillings into the emulsion well below the shroud.
The tuning stuff available on FCR suggested that 2mm always worked best on a 4T as the better emulsification gave better power - even though the AFR was a little
too lean up top due to the big air jet.
On the dyno I played with the replaceable main air jet, and settled on a 150.
As with this and the low shroud, its fuel curve was spot on.

I think what you guys are up against is the problem that has always plagued bleed carbs.
Dellorto and Weber have literally hundreds of tiny variations in bleed hole geometry to match a carbs fuelling to a specific engines needs.
Luckily it has been found that the primary type on a 2T is easily nailed, just with changes in needle shape, and an adjustable idle/air and main.

[Kickaha]

maybe this better link

http://www.simplicitymotorworks.com/

150cc, yeah that should be bucket eligible

[Ocean1]

150cc, yeah that should be bucket eligible

And with that big fuckoff prop you won't be short on elbow room going into the first corner...

[dinamik2t]

I accidentally just found out that Jan Thiel is a Facebook addict: https://www.facebook.com/Jamathi :shit: :p

There are some very interesting mechanical and historical photo there! Perhaps Frits could ask him, whether I could repost some of his photos here, as many wouldn't have a facebook profile.

[Frits Overmars]

I accidentally just found out that Jan Thiel is a Facebook addict: https://www.facebook.com/Jamathi. There are some very interesting mechanical and historical photo there! Perhaps Frits could ask him, whether I could repost some of his photos here, as many wouldn't have a facebook profile.I didn't have a Facebook profile either, I just registered because of what you wrote. Now I will have to learn to find my way around it.
I must say I'm a bit sceptical. I just don't believe in 'over a thousand friends' :chase:

By the way, if you want Jan's permission for anything, you will have to ask for it yourself, dynamik. Since both of you are on Facebook, that shouldn't be a problem.

[dinamik2t]

I didn't have a Facebook profile either, I just registered because of what you wrote. Now I will have to learn to find my way around it.
I must say I'm a bit sceptical. I just don't believe in 'over a thousand friends' :chase:

By the way, if you want Jan's permission for anything, you will have to ask for it yourself, dynamik. Since both of you are on Facebook, that shouldn't be a problem.

Yes, at first I was like "what's that, a facebook profile and personal photos? is that Jan Thiel?" - it seemed a bit strange., with all the respect! :confused:
I can't and shouldn't be judgemental on anybody about personal stuff, so excuse me.

As for the permission.. I didn't mean to have you 'do my dirty work'. I feel strange about asking things in personal, either facebook messages or PMs in forum. Plus, to be honest, I have a facebook profile for 'tuning demonstration/promotion' purposes only and I cannot help feeling embassared for my work against Jan Thiel's. Yes, that might be an inferiority complex, but.. ok.
Since you think it will be ok, I will send him a message.

p.s. I know there's no real word 'dinamik', but it's what my moto is called. so, if you don't forget, use the i :D

[dinamik2t]

So, Jan Thiel gave his ok. A few pics I found interesting:

https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash2/58100_163122007033936_100000084143345_499030_56350 58_n.jpg


"Jamathi cilinder 1967"
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc7/s720x720/432142_2705047274658_1511052910_31821015_203156668 1_n.jpg


Derbi ignition trigger
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/s720x720/425265_2704871750270_1511052910_31820964_125386035 9_n.jpg


Cylinder inspecting - with Giovanni Sartorato e Matteo Marini
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc7/s720x720/419655_2700427319162_1511052910_31819524_162373812 1_n.jpg


"Brno 1969, our best win! On the right is my Czech friend Olda Fiser."
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/s720x720/417117_2700019388964_1511052910_31819392_929438763 _n.jpg


"With my friend GJ Rigter at the Aprilia flowbench. The tool in my hand is for flowing the transfers. We flowed them with the piston in 4 different positions."
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/s720x720/429839_2700198193434_1511052910_31819441_137903243 6_n.jpg


"The front half of an Aprilia crankcase. The crankshaft could be fixed in various positions by a springloaded ball. We used this for flowbench testing. We could see that the conrod disturbed the flow very much, so the idea of the rear inlet RSA was born!
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc7/s720x720/429494_2685369942737_1511052910_31813005_192701034 3_n.jpg

[TZ350]

OK .... that was Te Puke, its a great tight track, lots of elevation changes and hair pin corners. The weather was fine Saturday wet Sunday, and rained all day long but great racing and times in the wet were much the same as the dry.

And Tokoroa was no fluke as Av managed :first::first::first:

Placings were:-

Race 1 Av :first: Gav-V :second: Rick :third: and Kel

Race 2 Av :first: Gav-V :second: Rick :third: and Kel

Race 3 Av :first: Gav-V :second: Kel :third: and Rick

So three 2-Strokes and Gav-V's FXR at the pointy end all day.

[marsheng]

I checked the emulsion air passage on a pile of different 2T type Keihin carbs when I converted a 4T FCR downdraft to work on a 2T.
They ranged from 1.7 to 1.9 mm - none were jets as such ,just drillings into the emulsion well below the shroud.



Thanks for the info. The original Honda carb has a similar emulsion tube and it's air jet was around 1.8 mm, so it looks like it is time to do some drilling.

[kel]

And Tokoroa was no fluke as Av managed :first::first::first:

Placings were:-

Race 3 Av :first: Gav-V :second: Kel :third: and Rick


Once again Avalon looked unstoppable.
I pulled a horsepower mugging on Rick in that last race. The beast was embarrassingly fast, clearly quicker up the straight than anything else on the track.

[Buckets4Me]

Once again Avalon looked unstoppable.
I pulled a horsepower mugging on Rick in that last race. The beast was embarrassingly fast, clearly quicker up the straight than anything else on the track.

and more likely to bite than the marshalls :shutup:

[Rick 52]

Thanks for team ESE ..Great advice on port tidying and a re designed pipe gave me 1/2 a horse and a much fatter power curve ,this kept me at the sharpe end all weekend ..now I need to stop the clutch from slipping ...
Kel a pass is a pass very clean and you still had to put the power down in tricky conditions and a tidy last lap left me nothing to get you back ,very good racing from us all I think ..

[bucketracer]

and more likely to bite than the marshalls :shutup:

Kels FXR was over the noise limit and he had to park it for the day.

[kel]

very good racing from us all I think ..
Agreed. The racing was fast, clean and a lot of fun.


and more likely to bite than the marshalls :shutup:
That was a draw, 1 each.


OK .... that was Te Puke ... So three 2-Strokes and Gav-V's FXR at the pointy end all day.
Did a quick calc and by my take with one round to go its team ESE riders 1st equal on 120, Rick 1 behind at 119.

edit: actually that should have read ESE riders equal on points, Avalon leads due to greater no. of wins. What really matters is that 2 strokes lead!

[wobbly]

Anyone got a set of dimensions for a TZ350G - crossover pipes, dont want to measure them if I can avoid it.
Want them as a sim baseline stock engine.

[bucketracer]

Great racing this weekend, sorry about the weather. This is how it looks...

120 Avalon Biddle
120 Kel Nicolson
119 Rick Ford
104 Steve Booth
83 Gavin Veltmeyer
71 Warrick Head
49 Andrew Adlam
41 Malcolm Nabbs
41 Mike Kyle
39 Carl Smith
38 Gary Cunningham
35 Rogan Chandler
34 Tim Fraser
34 John Steer
30 Ken Douglas
28 Kamil Chodor
26 Adrian Mitchell
25 Henk Zeeven
17 Ryan Firn
15 Grant Nicholson
15 Caleb Adlam
15 Ivan Smith
11 Dave Manuell
10 Brian Steffensen

See the quiet achievers like Steve Booth waiting in the background to jump when all the 2 strokes seize and Gavin gets a free holiday to Hawaii on short notice...

Given the mix of fast guys to come out at Kaitoke it could be a very dynamic last round.

The offical Pacific Club Summer Series results after Te Puke .... Strokers :first::second::third: making the FXR's the also rans.

Any of the nay sayers still unable to read the writing on the wall ........ with the Taupo GP next, things are getting interesting.

[koba]

I'm saving this spot for a post that is going to take some careful composition.

OK, now it's composted in my mind long enough I'm posting it:

I was going to write a lengthy and thoughtful post about my quick run on Avalons bike.
The length will have to come from me padding it out with worthless rambling thoughts because my short play run can be described in one word:
Outstanding!

No, I don't mean that in the way we describe Romanian plum brandy, which stands out as the most horrid liquid substance to my assault my palate; It was outstandingly good.
Most times I ride someones bucket I mentally cobble together a checklist of pros and cons. The better bikes, all the fast ones, don't really have cons. Instead they have Pros and Okays, for example Rick's old FXR had an unbelievable mid-range punch and turned in exceptionally well (for an FXR), there were no aspects of the bike that could be considered 'bad' by any means.
The ESE built GP framed bike that Avalon has been using to humble the fastest racers out there was nothing short of fantastic.
Before I snuck out after the last B-grade race Keith quietly said to me "Careful with the brake, feel it out as it's probably better than you are used to."
Shit, He wasn't kidding!
The brake wasn't all, every part that makes a bike stop, go, turn, handle and feel good was better than I've felt on any bucket before.
I only had a few laps on it but I was instantly aware the bike was much faster than me, on my second lap I realised I was riding it all wrong because I was still trying to force it around corners rather than just looking where I want to go and letting the bike do the rest. That's a cool feeling.
The bike is very fast but in the kind of way it will take a damn good rider to make the most of it. Sorted.

So the purpose of this post is to thank Avalon and Keith for letting me out on it, even when they wanted to go home! I must also congratulate all the ESE personnel for their work on creating such a gem of an engine, if I didn't know better I wouldn't have believed it was a 1970's commuter engine, it makes all the right sounds and goes like the hyper kid after he's been fed a bag of red lollies.

[F5 Dave]

I might as well save this spot for some careless compostation

[TZ350]

I am saving this spot for the post Taupo excusses I have composed ..... :laugh:

[koba]

I might as well save this spot for some careless compostation

you could put some of it in bottles and call it homebrew like I do...


I am saving this spot for a bunch of post Taupo excusses I have composed ..... :laugh:

If you show up you have to make excuses that fit reality, my excuses revolve around not showing up!

[TZ350]

EngMod2T

I am trying to decide wether to leave the bike as is for Taupo or to fit the new Wobbly pipe and maybe even the triple port cylinder. Its a bit of a hassle and a hours of dyno time to get the ignition curve and carb right.

The trick in looking at these curves is to not take the ultimate hp to seriously as EngMod thinks my combustion efficiency is much higher than it actually is. I could change that in the settings but can't be bothered because re running the simulations will take to long.

With these simulations the thing to look for is the shape of the curve and the power spread not the ultimate hp which is over stated by at least 3 hp and is at the crank and not what you would see on the dyno.

259649

Red line is the current 1ex setup with RS pipe, and the Blue line is the new Wobbly Pipe

259650

The Blue line is the current 1ex setup with Wobbly pipe, and the Red line is the 3ex (tripple ex) with Wobbly pipe.

259651

The Red line is the current 1ex setup with RS pipe, and the Blue line is 3ex (tripple ex) with Wobbly pipe.

Flat for 4,000 rpm 10-14K or a 5,000 power spread from 9-14K with over rev to 15, now thats tempting, and if we can plump up the 8 to 9 bit with an ATAC valve then thats potentialy 5.5 to 6k power spread. Guess what I will be working on over the next few months.

But what to do for Taupo, the tried and true or take a gamble ......

[Buckets4Me]

EngMod2T

I am trying to decide wether to leave the bike as is for Taupo or to fit the new Wobbly pipe and maybe even the triple port cylinder. Its a bit of a hassle and a hours of dyno time to get the ignition curve and carb right.

I recon you leave it as is and spend the time sorting the carb out :yes:
then i might be able to ride it better :yes:

[TZ350]

I recon you leave it as is and spend the time sorting the carb out

Yep you could be right, its fast enough now, better to leave it as is and save something for later, 33+ rwhp and 5.5k power spread, just in case the faster FXRs can find any more power.

[husaberg]

Anyone got a set of dimensions for a TZ350G - crossover pipes, dont want to measure them if I can avoid it.
Want them as a sim baseline stock engine.

I think Your friend Neels does i guess, his site advertising for enginemod2t uses a TZ250G as an example.

and also this guy uses the t250g as a sim example he has done if that helpshttp://www.thumpertalk.com/topic/782949-engmod2t-2-stroke-simulation-software/

Bell has the pipe dimensions for a TZ125G, TZ250D/E, TZ500G not that helps you much. As Mr Murphy helped him choose his examples, Maybe different editions offer different examples?
Mr Swarbrick will know them too, as he does T20 pipes to those std dimensions for classic racers as well.

[koba]

But what to do for Taupo, the tried and true or take a gamble ......

My vote would be tried and true for your situation, changes can cause problems that take time to iron out or only become apparent on the day, you aren't in the position where the risk is worth it.

[bucketracer]

...better to leave it as is and save something for later, 33+ rwhp and 5.5k power spread, just in case the faster FXRs can find any more power.

Maybe you could get to 33-35 rwhp, but you don't need it now, keep it like money in the bank then the FXR's will always know you can easily pull something out of the hat and stay ahead of them whatever they do.

[2T Institute]

So I suppose all this is why a GP125 is approaching Manx Norton prices on Trademe? :laugh:

Well done TZ, probably why the 'powers that be' wil never allow air cooled 125's here.

[Yow Ling]

So I suppose all this is why a GP125 is approaching Manx Norton prices on Trademe? :laugh:

Well done TZ, probably why the 'powers that be' wil never allow air cooled 125's here.

http://www.trademe.co.nz/Browse/Listing.aspx?id=452663122

didnt even get a $20 bid, now where are those nortons.

[Buckets4Me]

http://www.trademe.co.nz/Browse/Listing.aspx?id=452663122

didnt even get a $20 bid, now where are those nortons.

the truth is the fuel cap is damaged and i cant get fuel into it easily i dont know if the oil pump is working and i dont want to risk damaging the bearings or piston. its 6v im sure and i dont have a 6v charger to peak it up im kind of selling it as is cause i havnt had it running. tomorow ill wip out the plug and read it to see how its been running im good at reading 2stroke plugs i can tell its state of tuneby the plug. ive kickedit overslowly tosee comp and its good and its dry too. <small class="NoWrapping"> 10:37 pm, Sun 4 Mar </small> Seller Comment: i pulled out the plug its been running fine by the looks of thr plug little bit rich maybe <small>



thats maby why it didn't get a $20 bid
it's been sitting for how long and he can read the state of tune by doing a plug chop </small>:woohoo:
<small>
</small>

[Buckets4Me]

http://www.trademe.co.nz/Browse/Listing.aspx?id=452663122

didnt even get a $20 bid, now where are those nortons.

the truth is the fuel cap is damaged and i cant get fuel into it easily i dont know if the oil pump is working and i dont want to risk damaging the bearings or piston. its 6v im sure and i dont have a 6v charger to peak it up im kind of selling it as is cause i havnt had it running. tomorow ill wip out the plug and read it to see how its been running im good at reading 2stroke plugs i can tell its state of tuneby the plug. ive kickedit overslowly tosee comp and its good and its dry too. <small class="NoWrapping"> 10:37 pm, Sun 4 Mar </small> Seller Comment: i pulled out the plug its been running fine by the looks of thr plug little bit rich maybe <small>

</small><small>

and the auction was for a $20 key
how much do you pay for a manx norton key ?</small>:laugh:<small>
</small>

[wobbly]

Neels sent me a drawing of a TZ350F pipe he measured, but I also got a drawing from Bod Haldane ( Yamaha Factory ) and there are several quite big differences.
I will just have to measure a set for myself.
Bugger.

[F5 Dave]

http://www.trademe.co.nz/Browse/Listing.aspx?id=452663122

didnt even get a $20 bid, now where are those nortons.
Well my last GP I bought in large parts for $50. Just assembled it & ran great. Sold it for $150 which recovered the two $40 knobbies I'd put on it.

What?!?:confused:


Anyway it lives on & is back to road tyres & a riding school hack. Best one he's had, & he's had it like 10 years.

[dinamik2t]

Neels sent me a drawing of a TZ350F pipe he measured, but I also got a drawing from Bod Haldane ( Yamaha Factory ) and there are several quite big differences.
I will just have to measure a set for myself.
Bugger.

From a quick google images search under "TZ350 pipe" & "TZ350 exhaust":

a) http://www.perthstreetbikes.com/forum/f64/making-rz250-350-pipes-89901/index2.html
b) http://www.tz350.net/images/dyno_and_misc/rd350%20lc_performance_exhausts_design_by_greg%20s ims_reduced.jpg ..... from here : http://www.tz350.net/lcracer_article.htm
c) http://farm5.static.flickr.com/4063/4234852671_64a6bc9533_o.jpg ........ from here : http://2stroker.createforumhosting.com/surching-exhaust-measerments-yamaha-tz-350-6-port-3g300-t3745.html

Hopefully, the c) is what you 're looking for.
edit: oh, you seek the G letter, so probably not.

[TZ350]

BMEP: and why your not going to see any 12K rpm 30 hp FXR150's in F4

For those that missed it before BMEP is an important performance yardstick

http://www.epi-eng.com/piston_engine_technology/bmep_performance_yardstick.htm

Brake Mean Effective Pressure (BMEP) is a very effective yardstick for comparing the performance of one engine to another, and for evaluating the reasonableness of performance claims or requirements.

The definition of BMEP is: the average (mean) pressure which, if imposed on the pistons uniformly from the top to the bottom of each power stroke, would produce the measured (brake) power output.

Note that BMEP is purely theoretical and has nothing to do with actual cylinder pressures. It is simply an effective comparison tool.

Brake Mean Effective Pressure (BMEP)

http://www.engineersedge.com/engine_formula_automotive.htm

4-Stroke BMEP = (HP x 13000)/(L x RPM)
2-Stroke BMEP = (HP x 6500)/(L x RPM)

L = Displacement in Liters i.e., 80 cc = .08 Liters 1 ci. = 16.39 cc

BMEP for those who missed it the first time .... and why 4-strokes are inherently limited and will eventually go the way of the dinosaurs.

BMEP for a FXR150 making 25 rwhp ... 28 crank hp at 12,000 rpm

4-Stroke BMEP = (HP x 13000)/(L x RPM)

BMEP = (28 x 13000)/(0.150 x 12,000)

BMEP = 364,000/1,800

BMEP = 202 psi for the FXR150 4 stroke.

BMEP for a GP125 making 30 rwhp ... 33 crank hp at 12,000 rpm

2-Stroke BMEP = (HP x 6500)/(L x RPM)

BMEP = (33 x 6,500)/(0.125 x 12,000)

BMEP = 214,500/1,500

BMEP = 143 psi for the GP125 2 stroke.

A BMEP of 200 to 220 psi is supposedly the upper practical limit for naturally aspirated engines and is only currently being achieved by the likes of F1 race engines.

At 202 psi for the FXR, the FXR150's do not have much more development potential left unless they are spun to 13 -14,000 rpm or more but at 12k rpm and 143 psi for the 2-stroke there is plenty of relatively easy potential left for the little Moto4 race bikes, and the writing is truly on the wall for the 4's.

And with things like direct cylinder injection making 2-strokes cleaner and inherently more powerful and cheaper than 4-strokes the 2 strokers must make a come back on the world stage at some point, its just shear economics.

http://www.allpar.com/neon/stroke.html Two-stroke engines have long been promising because of better fuel economy, fewer parts, better efficiency and a smaller engine package (about two-thirds the size and weight of conventional engines) that would allow for more design flexibility.

More on BMEP http://hpwizard.com/bmep.html and lots of other interesting formula like wind resistance.

[F5 Dave]

ok lets do some simpler math

Litre road bike now pushing 170hp x0.15 (for 150cc) = 25.5hp

Developed to world super spec easy 200hp x 0.15 = 30hp.


But realistically, no way will reach that spec with FXR parts. Just want to poo in BMEP calculations.

[bucketracer]

ok lets do some simpler math

Litre road bike now pushing 170hp x0.15 (for 150cc) = 25.5hp

Developed to world super spec easy 200hp x 0.15 = 30hp.


But realistically, no way will reach that spec with FXR parts. Just want to poo in BMEP calculations.

What rpm is the world super spec 200hp engine spinning at.

I think TeeZee pointed out the FXR would have to spin to 13-14,000 rpm to make 30 crank hp and 30 was not going to happen at 12 which looks like their mechanical safe limit.

You might need to work through the math again as BMEP gives a true apples for apples comparison and indication of development potential, hp per liter does not.

[F5 Dave]

As I said simpler math, the rpm assumption was yours. Perhaps a GSXR600 rod may help with the revs. Can't help out being a single, mind.

Heck with . . .actually why am I giving the 4 stroke guys ideas again??:shutup:

[TZ350]

Your simpler math is interesting but can be misleading unlike the BMEP rpm thing which points out where you have to goto to realisticly expect 30 crank hp from a FXR150 and its about 14,000 rpm, its not going to happen at 12K, the numbers don't lie they only revel the direction required, the realitive difficulty ahead and get you thinking about what may be required to get there.

[crazy man]

a mate was telling me in japan they drag race fxr 150 and get 37hp at the rear wheel but thought about it , they must be useing nitro in them even though a better head with all the goodies just maybe you could with out nitro

[TZ350]

... a mate was telling me in japan they drag race fxr 150 and get 37hp at the rear wheel but thought about it , they must be useing nitro in them ...

BMEP for a FXR150 making 37 rwhp ... 40 crank hp at 14,500 rpm
4-Stroke BMEP = (HP x 13000)/(L x RPM)
BMEP = (40 x 13000)/(0.150 x 14,500)
BMEP = 520,000/2,175
BMEP = 239 psi for a FXR150 drag bike, that dosn't look impossible with a diet of meth and dash of nitro.

A better head, normally aspirated and 16,500 rpm still requires a BMEP of 210 so definatly a 37 rwhp FXR150 has to have chemical help like crazy man said or be bigger than 150cc.

See Dave, the BMEP concept is great for checking stuff out.

I posted this information about the BMEP concept in the true spirit of sharing and friendship

and the desire to depress the FXR boys before the GP at Taupo .... :D

[husaberg]

Neels sent me a drawing of a TZ350F pipe he measured, but I also got a drawing from Bod Haldane ( Yamaha Factory ) and there are several quite big differences.
I will just have to measure a set for myself.
Bugger.


Looks like i need glasses 350 aye i will have another look.

this book has it i don't have this book but someone will
http://www.tz350.net/images/booksvids/final_front_cover_on_printed_books.jpg
An extensive 350 page study of all Yamaha’s TD, TR, TA and TZ racers produced between 1959 and 1982.
125, 250, 350, 500, 700 and 750cc capacities, all models.
All changes between the models.
Over 200 b&w photos of bikes, components etc.
Portmaps and exhaust diagrams.
Full specification lists.
What each is like to own and ride.
Problems encountered with each model.
Serial number limits for every model.
How to identify each model from the others.
Plus a lot more!

http://www.tz350.net/yamaha_two_stroke_production_roadracing_motorcycle s.htm

[marsheng]

I read somewhere that the Honda 2 litre (2000S) cars have the same performance as an F1 car. What ??

Take Honda's HP as stated, scale the figure by the engine size ratios and then by the RPM ratios and you get a figure roughly what the F1 makes.

Ok Lets see, Honda says 247 hp at 8300. (2002 figures)

Volume conversion 3000/2000 * 247 = 370 hp (2002 was a 3 Litre F1 engine)
RPM conversion 18000/8300 * 370 = 804 hp ---- Not far of an F1 car in 2002. (PS BMW's did 19200 RPM)

BEMP does not lie !!

[TZ350]

I read somewhere that the Honda 2 litre (2000S) cars have the same performance as an F1 car. What ??

Take Honda's HP as stated, scale the figure by the engine size ratios and then by the RPM ratios and you get a figure roughly what the F1 makes.

Ok Lets see, Honda says 247 hp at 8300. (2002 figures)

Volume conversion 3000/2000 * 247 = 370 hp (2002 was a 3 Litre F1 engine)
RPM conversion 18000/8300 * 370 = 804 hp ---- Not far of an F1 car in 2002. (PS BMW's did 19200 RPM)

BEMP does not lie !!

Yep BMEP does not lie !!!

The 1999 S2000 is little behind the tuned FXR150's, BMEP is a great tool for compairing engines and possibilities.

259700

BMEP for the 1999 2L Honda making 237 crank hp at 8,3000 rpm

4-Stroke BMEP = (HP x 13000)/(L x RPM)

BMEP = (237 x 13000)/(2 x 8,300)

BMEP = 3,081,000/16,600

BMEP = 186 psi for the 1999 2000S Honda

259701259699

Honda S2000

Graham Bell tries out Honda's recently revised roadster.

Designed by some of the engineers behind Honda's winning F1 and CART engines, the S2000's two litre DOHC straight four (a configuration chosen for compactness) boasts such race-bred features as roller rockers, forged shallow skirt pistons, ladder frame main bearing stiffener and fibre reinforced aluminium for the cylinders. It's also smaller and lighter than Honda's regular two litre engine, and at 237bhp sets a new record for highest specific output for a normally aspirated production car engine.

Of course without some form of forced induction, getting such high power outputs from just two litres requires high revs, which in turn requires cams with high lift and long duration to provide sufficient valve opening to allow the engine to draw in large amounts of air/fuel mix. Great at high revs but crap at low revs, which is a real problem for a road car - or would be without Honda's ingenious VTEC system, which works by literally having two camshafts in one, with three cams (two mild ones sandwiching a central wild one) for each pair of valves.

http://www.pistonheads.com/doc.asp?c=120&i=5155

[Buckets4Me]

BMEP for a 2L Honda making 247 crank hp at 8,3000 rpm

4-Stroke BMEP = (HP x 13000)/(L x RPM)

BMEP = (247 x 13000)/(2 x 8,300)

BMEP = 3,211,000/16,600

BMEP = 193 psi for the 2000S Honda

Interesting, this requires more looking into.

the big question is did the JAP tuners make anymore H/P from the little 2000s ? or is that about all it can make

[Grumph]

If you're going to take 2 litre four strokes for comparison, at least take some well developed examples.
To be competitive in British touring car champs and european 2 liter, in excess of 300 bhp is needed....
This is achieved without Honda's tricky dicky cams.

Four stroke development in F4 will continue I'm sure. Injection must become more common too.
I had a set of 1098 Duc heads here a while back and there's no way in the world they could be run on carbs.
Carbs require a minimum air speed to work - with ports that big the air speed drops out of a carb's comfort zone but injection vaporises the fuel for you regardless of air speed.
Then there's the multi cylinder approach...and revs....

[husaberg]

Putting a new piston in a 50cc at the moment (okay its a scooter)... Idea's on getting the 10mm (im guessing) piston circlips in, bloody tiny little things anything bigger is piss easy. They are the open type, can't really use circlip pliers. Any hints?

At the time i answered with a wee touch of sarcasm (yes it is the lowest form of wit but you should play to your strengths.)

Anyhow i did see this today never seen it before but here it is.
http://www.accu-products.com/images/uploads/c-clipper.jpg

Product Information
Two Stroke Model - Plain Sleeve Type

Piston Pin Circlip Installation The Easier Way. The C-Clipper takes all the drudgery out of this job. No more fiddling with long nose pliers and little screwdrivers and retrieving dropped Circlips from inside the crankcase. One push and your done in less than 15 seconds a side every time.

Trust us, you will not want to do another rebuild without it.

Available for most two-stroke engines
http://www.accu-products.com/images/uploads/ps_c-clipper_t.jpg
http://www.accu-products.com/images/uploads/ps_c-clipper_d.jpg
Price: $43.50
http://www.accu-products.com/accu-products-specialties/c-clipper-circlip-installation-tool-2-stroke-model/prod_3288.html
The observant amongst you will not he has no rag stuffed down the crankcase.
Can't imagine it would be that hard to knock up one if you were so inclined of course it no doubt has a patent so you should ask for their approval first.:innocent:

OH yeah the hp calculations you guys are using f1 car engines:yawn:
Have a look at the real high HP engines like Drag cars would ya.:corn:
http://www.nhra.com/nhra101/classes.aspx

[koba]

Trust us, you will not want to do another rebuild without it.


That looks like one of those TV infomercials where they make a simple task like vacuuming seem such a chore you MUST try this new product that will make life sooo much easier.

[twotempi]

I think this is correct but others may know otherwise

With patent law you can copy one for your own use BUT not permitted to reproduce for resale.

How you deal with making one for a mate is another matter................ ??

[richban]

Four stroke development in F4 will continue I'm sure. Injection must become more common too.


Yep watching Moto3 with interest. If we could only make 200ph per litre. We might be able to keep up with the jones.

TZ you should go for broke. Tune that thing to the max. I here they run really good lean and hot. I will be bolting my engine in at the track at this stage.

[TZ350]

TZ you should go for broke. Tune that thing to the max. I here they run really good lean and hot.

Hot and bothered, year right ... :bleh: ...... only two weeks to go, I am looking forward to catching up, see you there.

[richban]

Hot and bothered, year right ... :bleh: ...... only two weeks to go, I am looking forward to catching up, see you there.


Yeah seems like we did this only a few month's ago.

[husaberg]

I think this is correct but others may know otherwise

With patent law you can copy one for your own use BUT not permitted to reproduce for resale.

How you deal with making one for a mate is another matter................ ??


with patent law no no no no you can't. I think.
A guy did that in the south island with a rotary cowshed he lost. He had copied a plan and the novel method of locating the platform on Bearing's rather than pedestal rollers or a round track with wheels it had kind of like a ball race only with Nylon balls located in a concrete groove cast into the platform the original designer was from Murchison and he did the legal challenge thing.
The shed was i think a self build in the Waitaki basin or there about's i think.(Having said that it was used in a commercial sense so who knows)
Rotary cowsheds like most great farming ideas was invented here in good old NZ. (The old Dutch are a bit behind on those such things):bye:

Although i don't see a patent number or copyright any where there in the add.

That looks like one of those TV infomercials where they make a simple task like vacuuming seem such a chore you MUST try this new product that will make life sooo much easier.

And yeah with you Koba that's why i said to stuff a rag in the case. But then again i don't have sausage fingers or 10mm gudgeon's either.
ps the misses say's vacuuming is hard work. i will have take her word for it. Just like the whole Baby birth labour thing is so painful stuff. How would I know:violin:

Having said that my articles I post er.....oh..... they are credited at least to the publisher and in most case the author i guess.:innocent:

[kel]

TZ you should go for broke. Tune that thing to the max.

Do it chief, Wobbly pipe and all! We should insist Wob orders another run of these shirts and brings them to Taupo.
"YOU'RE BEHIND ME COS I'VE GOT A WOBBLYPIPE - I had 50 of these T shirts to give to World and National Championship winners , sorry all gone"
:Punk:

Rich, make sure you leave the pin in that hand grenade this time

[speedpro]

I will be bolting my engine in at the track at this stage.

I'm thinking one "before" and one "after".

You should check if Dzus do engine bolts, could be useful.

Some sort of explosion containment system could be a good idea so you don't get any more . . . . "popular" :whistle:

[richban]

Some sort of explosion containment system could be a good idea so you don't get any more . . . . "popular" :whistle:

Dude I am super popular. Got invited to a Tupperware party the other day. Good stuff I tell yah. I am sorry about causing you pain with the oil spill. My wallet is suffering as well.

[speedpro]

Shit happens. I'm nearly over it.

[husaberg]

Dude I am super popular. Got invited to a Tupperware party the other day. Good stuff I tell yah. I am sorry about causing you pain with the oil spill. My wallet is suffering as well.


Reading between the lines rather than the results
Was there an engine incontinence incident.
From what i understand it is common oversea's as far back as the mid 90's for un house trained 4 stokes to be made to Wear "Diapers" (IE belly catch tanks)
Shame yo hear though, again as well Rich.
is the carb and new piston ok?

Oh yeah how many engines does Rich have to disembowel before he is classified as a serial killer, or is in Euthanasia:shit:

[F5 Dave]

Do you not venture far out of this thread?? Try looking at his Autopsy thread.

[marsheng]

If you're going to take 2 litre four strokes for comparison, at least take some well developed examples.
To be competitive in British touring car champs and European 2 liter, in excess of 300 bhp is needed....
This is achieved without Honda's tricky dicky cams.
.

They can't get 300 bhp at 8300. Yes they can, but at 10000.

In fact you can get 1000 hp from a 2 litre. You just have to spin the motor fast enough. However the technology hasn't been developed as yet.

When a fixed amount of fuel and air burn, they give out a fixed amount of energy. The BEMP is just a measure of how well the engine utilizes the capacity of the engine. It's much the same as the volumetric efficiency.

The faster you can get air and fuel through the motor, the more HP you produce.

[Yow Ling]

They can't get 300 bhp at 8300. Yes they can, but at 10000.

In fact you can get 1000 hp from a 2 litre. You just have to spin the motor fast enough. However the technology hasn't been developed as yet.

When a fixed amount of fuel and air burn, they give out a fixed amount of energy. The BEMP is just a measure of how well the engine utilizes the capacity of the engine. It's much the same as the volumetric efficiency.

The faster you can get air and fuel through the motor, the more HP you produce.

In 1986 F1 cars were making 1500 hp from 1500cc in qualifying and 900 hp in race tune. The dog had its day back then

[wobbly]

The BMEP figures are for natuarally aspirated engines - wacking a turbo on the side throws all the rules out the window.
And a full noise 2T engine cant compete with the turbo 4T size for size.

[TZ350]

If you're going to take 2 litre four strokes for comparison, at least take some well developed examples. To be competitive in British touring car champs and european 2 liter, in excess of 300 bhp is needed....


They can't get 300 bhp at 8300. but yes they can get 300 at 10000.
In fact you can get 1000 hp from a 2 litre. You just have to spin the motor fast enough. However the technology hasn't been developed as yet.

Lets check, Grumph does not give an rpm figure but we can make some educated guesses.

And a BMEP of 200-220 psi is not set in stone its just where most normally aspirated high performance engines are at for now.

So we can use BMEP to check what's needed to make 300hp from 2L and whether we think its possible.

4-Stroke BMEP = (HP x 13000)/(L x RPM)

BMEP for a 2L making 300 crank hp at 8,3000 rpm
BMEP = (300 x 13000)/(2 x 8,300)
BMEP = 3,900,000/16,600
BMEP = 235 psi for 300hp @ 8,300

235psi BMEP is unlikely for a normally aspirated engine, so its more likely to be being reved higher than 8,300.

BMEP for a 2L making 300 crank hp at 10,000 rpm
BMEP = (300 x 13000)/(2 x 10,000)
BMEP = 3,900,000/20,000
BMEP = 195 psi for 300hp @ 10,000 rpm

We get a more likely BMEP of 195 if the engine can run to 10K so like Grump says, a 300hp 2L normally aspirated engine is possible, but we can see from the BMEP figures that it is only if you can rev it to about 10K.


When a fixed amount of fuel and air burn, they give out a fixed amount of energy. The BEMP is just a measure of how well the engine utilizes the capacity of the engine. It's much the same as the volumetric efficiency. The faster you can get air and fuel through the motor, the more HP you produce.

BMEP for a F1 engine is typically 200-220 psi and a top fuel dragster 1,100-1,500 psi, there is no BMEP limit other than a mechanicaly practical one, and there are typical ranges for the type of motor your looking at.

From Wiki, rule of thumb BMEP pressures for:-

Naturally aspirated spark-ignition engines : Maximum BMEP in the range 8.5 to 10.5 bar (850 to 1050 kPa; 125 to 150 lbf/in2), at the engine speed where maximum torque is obtained. At rated power, bmep values are typically 10 to 15% lower.[2]

Boosted spark ignition engines : Maximum BMEP in the 12.5 to 17 bar range (1.25 to 1.7 MPa; 180 to 250 lbf/in2).[3]

Naturally aspirated four-stroke diesels: Maximum BMEP in the 7 to 9 bar range (700 to 900 kPa; 100 to 130 lbf/in2).[4]

Boosted automotive four-stroke diesels : Maximum BMEP in the 14 to 18 bar (1.4 to 1.8 MPa; 200 to 269 lbf/in2) range.

Two-stroke diesels have comparable values, but very large low speed diesels like the Wärtsilä-Sulzer RTA96-C can run at BMEPs of up to 19 bar (1.9 MPa; 275 lbf/in2).

Ultra boosted engines such as the engine used in the Koenigsegg Agera can run at BMEPs as high as 28 bar

Top Fuel dragster engines: 80–100 bar (8.0-10 MPa 1,152 - 1,440 psi)

And from http://howautowork.com/part_1/ch_2/Engine_Desgin_and_Performance_Data_15.html

259726 (http://howautowork.com/part_1/ch_2/Engine_Desgin_and_Performance_Data_15.html)

[pete376403]

In 1986 F1 cars were making 1500 hp from 1500cc in qualifying and 900 hp in race tune. The dog had its day back then

Wasn't a day, was more like 8-10 minutes (BMW 1500 in qualifying trim). In race trim they could last about an hour.

[2T Institute]

http://www.trademe.co.nz/Browse/Listing.aspx?id=452663122

didnt even get a $20 bid, now where are those nortons.

Just needed a good description, with witty prose like ................."this bike is so tough that all Chuck Norris could do to it was break the the blinker"..............."this bike has sooooo much awesome that if you rev it up and dump the clutch, you don't go anywhere. Because it makes the earth spin backwards"


Just wondered has TZ put the longest rod possible in?

[TZ350]

Just wondered has TZ put the longest rod possible in?

Currenty using a RGV250 rod at 105mm and have previously used a RZ250 rod at 110mm center to center.

[dinamik2t]

Tz, now that we're talking about your moto, please remind me: how much difference was there from reducing the duct entry to about 1.2xport ?

[TZ350]

Tz, now that we're talking about your moto, please remind me: how much difference was there from reducing the duct entry to about 1.2xport ?

Are we talking about the simulation or on the dyno.

[dinamik2t]

I 'd prefer dyno. Could you make an estimation of the ratio before adding the epoxy?

[TZ350]

I 'd prefer dyno. Could you make an estimation of the ratio before adding the epoxy?

259789

I am currently running the cylinder on the left. If you mean the cylinder on the right I have never realy given it a good pre glue run but it was the barrel used for the first ever recorded F4 engine to touch 30 rwhp. Testing had to stop as it was so out of ballance at 14k that it was frothing the fuel up in the tank and it was overflowing and running down all over the hot bits. I stopped testing before we had a BBQ.

I have just had it rebored and are planning on giving it a proper run on the dyno after Easter.

Kel and I are playing it cautious with the GP in little over a week and Kaitoke at Easter any more experimenting will have to wait for a bit.

There are a few new things I want to try, like the new Wobbly pipe, the tripple port with glued transfers, a boost bottle, an electronic power jet thing with TPS and re visit the plenum.

Then there is the experiment with the two 24mm carbs, one with the venturi in front of the slide and the other behind in back to back tests with a 30mm carb to see what differences are, if any.

And the bigger rotary valve.

I think in there somewhere is lurking 35 rwhp.

[husaberg]

There are a few new things I want to try like the new Wobbly pipe, the tripple port with glued transfers, a boost bottle and re visit the plenum.

as well as too Vtac,(Or what ever it was called) Attac, Electric powerjet shortened intake ,slippery disk, larger disk..........
All pics from out of TZ's excellent library
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=254506&stc=1&thumb=1&d=1325738109http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=254658&stc=1&thumb=1&d=1325865028http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=245996&stc=1&thumb=1&d=1314856926http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=240407&stc=1&thumb=1&d=1306623845http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=230483&stc=1&thumb=1&d=1296426177http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=256571&stc=1&thumb=1&d=1327120798http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=230471&d=1296423695&thumb=1http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=230305&stc=1&thumb=1&d=1296328301
What actually is the combustion chamber shape and comp ratio TZ?

[TZ350]

What actually is the combustion chamber shape and comp ratio TZ?

Semi Toroid and 7.4:1 corrected. (9cc, ex opens 78.5 deg ATDC)

[TZ350]

Simultaed Crank hp, it may be overstated by about 4-5 hp, but its the relative differences that are important as you can expect them to show up the same way in the engine.

259793

Red line is the Plenum and it adds a boost in the 12-14K area, the Blue is a Boost Bottle and Orange is the 24mm OKO.

I have been playing around with the simulator again and have been able to simulate a boost bottle and plenum (air box) similar to the plenum we made a while back.

I am not sure if EngMod2T can do both airbox and boost bottle together, hopefully there is a way. Anyway plenty to tryout on the dyno after the last round of the Pacific Clubs Summer series at Kaitoke over Easter.

The Plenum giving a boost in the 12-14K area is just what I would expect if the 24mm carb was limiting the top end power output.

Now that we look like we are getting to the end of what a conventional 24mm carb can pass the plenum might usefully add something, anyway EngMod2T thinks so, so we are just going to have to try it out again.

[2T Institute]

What piston? Comp height? Did you get much benefit from the 110mm rod (air cooled RD 250/250 rods are a better rod BTW). Did you use a spacer plate with the 110mm rod?

[dmcca]

Tz, now that we're talking about your moto, please remind me: how much difference was there from reducing the duct entry to about 1.2xport ?

I'm interested in dyno proof of this too... Tried it on several bikes and my bum tells me it's a good thing but I can't seem to get engmod to show much if any difference.

[dinamik2t]

Yes, I was curious about that, because the sim shows some difference, but not much.
Also, I am very curious whether I am measuring the duct enty area correctly - or at the correct point. I have found area ratios close to 1.5 for tfrs and 2.5-3 for boost ports in a few cylinders:( Seems pretty large.
All of these cylinders have the sleeve side of the duct at the same level as the outer/flange side. I just lay a milimetric paper on it, shape the edges and count squares...
In addition to that, 125mx/gp ducts look so big! Makes me wonder.:mellow:

[TZ350]

Did you use a spacer plate with the 110mm rod?

259799

Yes used 10-12mm spacer, depending on the rod piston combo.

259800

At first it was just an alloy plate then Thomas suggested putting the spacer to use as cooling too. The black piece in the picture is a heat insulator.

259801

So the spacer now adds volume, stops a lot of cylinder heat getting to the crankcases and directly cools the exhaust port area through contact with the copper bars.

259798

Multi tasking cylinder spacer.

[wobbly]

What you have to realise is that because EngMod is a 1D simulation it cannot predict changes is flow regimes due to duct geometry.
Making the entry area 1.2 instead of 1.5 will change the volume, and this is what the sim "sees" but this change will dramatically affect the flow thru the duct into the port.
Its the same with say port stagger,this dramatically affects the scavenging regime, all the sim sees is the high ports affect on blowdown and calculates this change.
What you have to do is look at what is being done in the fastest engines on the planet and translate that experience to the project at hand.
This is why the sim is overpredicting the power of the GP125, it knows nothing about the duct shortcomings, even though the numbers may be similar to a RSA.
Neels hates fudge factors, but what we need to pull the power down,is a factor that represents a " % of shit design " that we cant modify out of our projects.

[sonic_v]

What you have to realise is that because EngMod is a 1D simulation it cannot predict changes is flow regimes due to duct geometry.
Making the entry area 1.2 instead of 1.5 will change the volume, and this is what the sim "sees" but this change will dramatically affect the flow thru the duct into the port.


The transfer ducts are modelled exactly the same as the exhaust system hence in effect the ducts can behave like diffusers when the cylinder pressure is above the crankcase pressure ( This is rarely good for power as it increases backflow into transfer duct). Hence a 1.5 area ratio is a steep angled diffuser and a 1.2 area ratio is a shallow angle diffuser and thus the code is doing more that just a volume change.

However, the code knows nothing about the finer details such as inner and outer radius of duct etc.

Sometimes going down to a ratio of 1.05 or even 1.0 can be good from a simulation point of view.

[TZ350]

The interest at the moment is modelling a boost bottle and plenum.

259823

Here is a bit of info on Boost Bottles.

259825

Engine http://wikiscootia.wikidot.com/boost-bottle#toc1

Theory http://www.mopedarmy.com/forums/read.php?1,843707

259824

How to calculate the Sizes required. http://49ccscoot.com/boost.html

And making your own is not that hard.

[wobbly]

Yes I agree the sim calculates the transfer duct as a tapered pipe taken from the dimensions given, from this it calculates the volume.
And yes I also agree that it cannot know if it is ( although it must assume that it is ) a constant taper.
The less the real duct conforms to this ideal, the less accurate the sim is in its calculations in relation to the real diffuser.
Neels visits here sometimes - maybe he could enlighten us if any calculations are done for reverse flow down the duct, when blowdown overcomes case pressure, and the transfer duct actually acts as a diffuser and not a contraction.

TeeZee, Neels has sent us both the latest version to install.
Resend the packed sim when you have this done - and I will report if it crashes.

A boost bottle setup helps throttle response when getting back on the gas, after coasting into a corner at low rpm.
Could be usefull on a sprint track.
The ATAC boosts the whole bottom end, off the pipe, and works much more effectively due to the greater wave intensity in the header.

[husaberg]

The interest at the moment is modelling a boost bottle and plenum.


Here is a bit of info on Boost Bottles.

And making your own is not that hard.


My thoughts based on gut instinct is the boost bottle would be quite beneficial esp with the restricted size carb.
I hazard a guess that it would be more beneficial than the original plenum certainly it should be a lot less problematic with the fueling.

What about a convoluted tube so you can alter the length/volume during testing quickly?
http://t0.gstatic.com/images?q=tbn:ANd9GcQscow4Gx0CnTg--X6qsxktvBb7PjU-btivGb1_WoNEk5TnV34F

Or an air bladder mounted in the reservoir internally to tune the volume much like a pressure tank TZ will be well familiar with,
which could even be pulsed to alter the volume or even absorb/reflect pressure waves. just spit balling on the last bit.
If you have seen an home made water ram made with a old bike tube inserted you will have an idea what i mean.

[TZ350]

I will get that sim update sorted.


A boost bottle setup helps throttle response when getting back on the gas, after coasting into a corner at low rpm. Could be usefull on a sprint track.

This would have been usefull at Te Puke.


The ATAC boosts the whole bottom end, off the pipe, and works much more effectively due to the greater wave intensity in the header.

An ATAC valve is very much on my to do list.

[TZ350]

259842

Interesting, whatever way you cut it, most of the votes are going to two strokes, could this be another sign of where things are going at the pointy end of Moto4 (affectionately known as Buckets).

[F5 Dave]

My thoughts based on gut instinct is the boost bottle would be quite beneficial esp with the restricted size carb.
I hazard a guess that it would be more beneficial than the original plenum certainly it should be a lot less problematic with the fueling.

What about a convoluted tube so you can alter the length/volume during testing quickly?
http://t0.gstatic.com/images?q=tbn:ANd9GcQscow4Gx0CnTg--X6qsxktvBb7PjU-btivGb1_WoNEk5TnV34F

Or an air bladder mounted in the reservoir internally to tune the volume much like a pressure tank TZ will be well familiar with,
which could even be pulsed to alter the volume or even absorb/reflect pressure waves. just spit balling on the last bit.
If you have seen an home made water ram made with a old bike tube inserted you will have an idea what i mean.
BTW intake pressure will suck flat anything that isn't pretty rigid. Although Suzuki have got away with using just hose on the RG150, but it is rigid wrt to its dia.

[husaberg]

BTW intake pressure will suck flat anything that isn't pretty rigid. Although Suzuki have got away with using just hose on the RG150, but it is rigid wrt to its dia.
Yeah it could the only way to be sure is to suck and see. Admittedly i posted the pic wasn't great example of what i was meaning (i was in a hurry.)
I do believe it will be a bit more rigid then you think though.remember (vacuum cleaners) They have amazing strength in regards to crush from their shape and material concentration.
Hence its uses on some automotive intakes. From memory some FWD cars and even karts also have sturdy steel convoluted tubes as well on exhausts.

[TZ350]

EngMod2T

259848

Red line boost bottle as close to the Rotary Valve as I can get it and Blue line BB mid way between RV and Carb Slide, all other conditions the same. The stuff you can easily find out in half an hour using the EngMod simulator.

That would have taken me several nights on the dyno to find out?

[F5 Dave]

Yeah it could the only way to be sure is to suck and see. Admittedly i posted the pic wasn't great example of what i was meaning (i was in a hurry.)
I do believe it will be a bit more rigid then you think though.remember (vacuum cleaners) They have amazing strength in regards to crush from their shape and material concentration.
Hence its uses on some automotive intakes. From memory some FWD cars and even karts also have sturdy steel convoluted tubes as well on exhausts.

intakes are open at one end. All I know is I did suck it & see, but by all means, go ahead & retry what I already know.

[TZ350]

Page 460 already ....

[husaberg]

intakes are open at one end. All I know is I did suck it & see, but by all means, go ahead & retry what I already know.

Not sure really how to take that Dave, but wouldn't it be a little more constructive to suggest what you did try and didn't work.
That is the idea of the thread after-all. I did a search on boost bottles on the thread and came up empty in regards to what you had tried, just this.


Pah! What a load of bollocks (no offense I mean the bolt on goodies merchants website). I love these descriptions of what is supposed to be happening & how it will cure the common cold etc.

Yamaha made these famous in the 80s on their MX bikes. But there is a reason you don't see them on modern high performance bikes. (well infact the RG150 has one, but in the form of a long rubber tube). They are really only useful as a plaster for a badly designed (or rather mismatched) pipe. TSR software will tell you how to design one for the area you are trying to affect.

I made an adjustable one for the H100 (now Sketchys bike). The reason was the pipe I designed had too steep of a baffle cone & it caused a dip before peak power. As it was just a for fun bike & I couldn't weld back then (or worth a damn now), I left the pipe as it was. It curved around so modifying it was a big job.

So on with the bottle of the ~right size & I trimmed the tube to suit. I then made an adjustable bottle & plugged it into the manifold. Worked quite nicely to flatten out the dip, at least a bit.

Yeah with regards to materials Yamaha's IT175 one was from memory plastic and not that thick. Come to think of it so were the NSR ones.
Here is another plastic bottle combo Dave. Maybe suck rather than spit?:bye:
http://t1.gstatic.com/images?q=tbn:ANd9GcS9M-Z3Z4xXivU5XvR6ATqcR-jNv3E9r86qNHktGNLryb8sMHZ9

[TZ350]

259894

Remember that Vtec thing we made from an old SU carb in the hope of improving the bottom end. And it worked OK cleaning up the low end carburation nicely but made the carb stick out to far and limited the top end over rev.

259895

well, now that the plenum is going to get another outing it looks like the Vtec thing will fit inside OK and could do something usefull too.

Instead of the long tuned length spacer going under the bell mouth, the Vtec thing could go there. The hose on the spacer is an oil feed line.

And here it is simulated in EngMod2T.

259890

A graph of the Plenum and Vtec thing.

Red line is with the Vetec valve open and Blue line with it closed and the Orange line is with it opening at 10,000.

Some of these old projects are starting to look usefull again.

[TZ350]

EngMod2T

I have been trying to simulate my plenum and a boost bottle and found EngMod was not a 100% setup for that configuration so I talked to Wobbly about it and he must have talked with Neels because today I receved an update that covered several plenum layout options.

Now, how is that for service....... dam good I recon.

259940

This is the layout I am trying to model.

259942 259941

These are the other configurations.

[Frits Overmars]

A boost bottle evens out the flow fluctuations in the inlet system so that the flow through the carb is more constant. But a plenum does the same job more effectively. So if you use a plenum, you don't need a boost bottle.
If you insist on using a boost bottle, pick a bottle volume of about twice the cylinder capacity, use a hose diameter of about 0.7 * the carb diameter, start with a hose of about 200 mm length and tune it step by step with a pair of scissors. None of the components are critical; you just need to search the right combination. And that will only cost you a length of hose.

There are two things to remember:
First: because a boost bottle produces a more even flow velocity through the carb, the suction signal will be weaker, so you may need to fit bigger main and needle jets. That is also valid for a plenum.
Second: mount the boost bottle so that petrol cannot form a puddle inside the bottle, or it will play havoc with your carburation.

[husaberg]

A boost bottle evens out the flow fluctuations in the inlet system so that the flow through the carb is more constant. But a plenum does the same job more effectively. So if you use a plenum, you don't need a boost bottle.
If you insist on using a boost bottle, pick a bottle volume of about twice the cylinder capacity, use a hose diameter of about 0.7 * the carb diameter, start with a hose of about 200 mm length and tune it step by step with a pair of scissors. None of the components are critical; you just need to search the right combination. And that will only cost you a length of hose.


Thanks Fits but how do you stop the plenum upsetting the carburation?is there a way to do it without this happening?
i seem to remember tz having to pump out the wet fuel previously.

[TZ350]

Thanks Fits but how do you stop the plenum upsetting the carburation?is there a way to do it without this happening?
i seem to remember tz having to pump out the wet fuel previously.

I have a scaveng pump drawing from the bottom of the plenum, but any ideas would be very helpfull.

[Frits Overmars]

Thanks Fits but how do you stop the plenum upsetting the carburation?is there a way to do it without this happening?
I have a scaveng pump drawing from the bottom of the plenum, but any ideas would be very helpfull.
How about having the exit from the plenum to the engine at the lowest point of the plenum? Goes for boost bottles too. Just a thought.... :whistle:

[TZ350]

A boost bottle evens out the flow fluctuations in the inlet system so that the flow through the carb is .........

Thanks for the info on Boost Bottles. If BB's are your thing its worth checking out Frits post.


How about having the exit from the plenum to the engine at the lowest point of the plenum? Just a thought.... :whistle:

I intend recycling my old plenum for a few tests and if the results and EngMod simulations are really encouraging I will see what can be done.

I remember you suggested this before and it would be ideal, unfortunately its a bit hard to arrange, but is what we will do if the plenum idea looks like it has merit. And with a plenum of 2-3L I have to make provision for releasing any combustion pressure (BIG BANGS) that might occur in the plenum itself.

[TZ350]

259989 259990

This is the arrangement that I tried ages ago to get around the restriction of a 24mm carb. At the time every one sortof thought a 125 couldnt get past 20 RWHP because of the carb restriction. Well that turned out not to be true, but now at 35 crank hp I think we are getting to the limit of the 24, so its time to re visit the plenum idea.

Basicaly the plenum gives the 24 carb more time to pass the required air so we can push the hp up a bit further.

259988

One of EngMod2T's optional layouts is like my arrangement with the carb on the outside and the cylinder drawing air/fuel mixture directly from the plenum.

The idea was that the motor sucked from the plenum through a big unrestricted inlet and the 24mm carb had plenty of time to refill the plenum between suction events.

[F5 Dave]

Not sure really how to take that Dave, but wouldn't it be a little more constructive to suggest what you did try and didn't work.


Well I'll tell you a lightweight plastic bottle will get sucked flat.

[wobbly]

Havnt had a chance to look at the sim TeeZee.I was at Hampton watching Andy battle in the Superbikes, and Discombe battle the pre 89, 600 diesels
on his C model pre 82 TZ350.Great racing.

[jasonu]

I will get that sim update sorted.



This would have been usefull at Te Puke.



An ATAC valve is very much on my to do list.

Here ya go a brandy new one
http://www.ebay.co.uk/itm/HONDA-RS125-STEEL-FRAME-NEW-ATAC-EXHAUST-FLANGE-RACE-BIKE-HRC-RSC-/180844805445?pt=UK_Motorcycle_Parts&hash=item2a1b30bd45

[bucketracer]

Here ya go a brandy new one
http://www.ebay.co.uk/itm/HONDA-RS125-STEEL-FRAME-NEW-ATAC-EXHAUST-FLANGE-RACE-BIKE-HRC-RSC-/180844805445?pt=UK_Motorcycle_Parts&hash=item2a1b30bd45

Interesting that the blade opens inline with the gas flow and not accross it like we thought it should.

[TZ350]

Reusing these old parts for testing and Prof of Concept.

260041

Scaveng pump and the smaller pumper carb which is going to be converted into a direct injection oil pump.


because a boost bottle produces a more even flow velocity through the carb, the suction signal will be weaker, so you may need to fit bigger main and needle jets. That is also valid for a plenum

That could explain why I had to go from a 140 to a 180mj when I first tried the plenum idea.

Engmod2T simulations show an improvement with a plenum or boost bottle but I couldn't get anything extra by combining them, Frits said I wouldn't need both.

[husaberg]

Interesting that the blade opens inline with the gas flow and not accross it like we thought it should.
Same as a Cr125 one then. (the blade opening bit that is) they are one ebay $15-100 us occasionally. here is one here. It's possibly the worse one i have seen on Ebay at the dearest price as well.
http://http://www.ebay.com/itm/Honda-1986-CR-125-Cylinder-ATAC-Power-Valve-Exhaust-Manifold-Chamber-/390395992855?pt=Motorcycles_Parts_Accessories&hash=item5ae56a1b17&vxp=mtr (http://www.ebay.com/itm/Honda-1986-CR-125-Cylinder-ATAC-Power-Valve-Exhaust-Manifold-Chamber-/390395992855?pt=Motorcycles_Parts_Accessories&hash=item5ae56a1b17&vxp=mtr)http://i.ebayimg.com/t/Honda-1986-CR-125-Cylinder-ATAC-Power-Valve-Exhaust-Manifold-Chamber-/00/s/MTA2NlgxNjAw/$(KGrHqNHJEgE8oY,psQNBPToW+Jdi!~~60_57.JPGhttp://i.ebayimg.com/t/Honda-1986-CR-125-Cylinder-ATAC-Power-Valve-Exhaust-Manifold-Chamber-/00/s/MTA2NlgxNjAw/$(KGrHqJHJC!E9!S!lMoRBPToWzT0Mw~~60_57.JPGhttp://i.ebayimg.com/t/Honda-1986-CR-125-Cylinder-ATAC-Power-Valve-Exhaust-Manifold-Chamber-/00/s/MTA2NlgxNjAw/$(KGrHqJHJCIE9Ep1Utj3BPTo(SvP(g~~60_57.JPG


I thought i sent a link to TZ a while back for one $15 and brand new looking?

[richban]

Hey Guys

Just wondering about carb angle v float level. I have noticed that some PWK's are run at quite steep angles mine is not to bad but was just wondering if you need to make any major adjustments to the float hight V angle of the carb.

I was looking over an RS250 manual and it says the standard 16mm for the float hight and the carbs are on a really large angle. 1989 rs250 that is.

[timg]

Hey Guys

Just wondering about carb angle v float level. I have noticed that some PWK's are run at quite steep angles mine is not to bad but was just wondering if you need to make any major adjustments to the float hight V angle of the carb.

I was looking over an RS250 manual and it says the standard 16mm for the float hight and the carbs are on a really large angle. 1989 rs250 that is. Use gravity - make 'em vertical. See ya Friday :ride:

[Frits Overmars]

Interesting that the blade opens inline with the gas flow and not accross it like we thought it should.Why would you think that? Opening the blade across the flow would have three big disadvantages. It would be much more of a disturbance to the flow, it would heat up the blade much more, and the flow colliding against the protruding half of the blade would constantly try to rotate it. As the flow direction is alternating so close to the cylinder, that would mean a constant hammering on the governing mechanism.

[bucketracer]

Why would you think that? ...

Because in trying to understand them I saw a picture of one and it was described that way, it made sense at the time that the flow path could be extended that way.


Opening the blade across the flow would have three big disadvantages. It would be much more of a disturbance to the flow, it would heat up the blade much more, and the flow colliding against the protruding half of the blade would constantly try to rotate it. As the flow direction is alternating so close to the cylinder, that would mean a constant hammering on the governing mechanism.

Thanks that makes a lot of sense.

[wobbly]

Honda obviously found out how to make these things work just as I did.
As short a connecting tube as you can get, diameter about 1/2 the header,ATAC vol about the same as the cylinder swept vol.
We had about 1/3 of the throttle plate hanging down in the header when it was open, in line with the flow direction.
By experiment you find the point where the resonating volume starts to kill power, and then go back a couple of hundred rpm, and snap it shut with a rpm driven solenoid.
Easy with the Ignitech programmable output.
There is NO advantage to ramping the closing point ie interconnecting it with the PowerValve is nowhere near as effective as a single point solenoid action.
Spencers Honda 500 Tripple had two of them on the outer pipes, and it was completely unrideable without them.
You could get even better useable band width by having a double volume system, where another plate valve opened and shut the entrance to a second bottle vol.
The two being open initially, then the second vol being shut off, creating a much smaller vol that was then shut of at a higher rpm.
But hey the simple thing works a treat on engines with no option for a PV.

Re the carb angle.You will find that if you go up at too high an angle that the pilot circuit will spew fuel into the carb under brakes, as the level rises in the front of the bowl.
Only way to fix this is to drop the fuel level, but then you risk having a too low level around the mian jet well.
This can be helped by making a main jet extension spacer and fitting a deep nut on the bowl.

[bucketracer]

Thanks for that, helps a lot.

[twotempi]

Most japanese engines use thrust washers each side of the bigend / cranshaft faces, but some Italian ones do not use them at all. The bigend eye bears against the crankshaft boss.

Are they necessary ?? what are the pros and cons ?? Also 1mm thickness seems a sensible minimum.

Information and comments please

thanks

[F5 Dave]

Are they shimmed in the pistons? RG400s/500s had some queer arrangement with thrust washers in SE.

[husaberg]

Most japanese engines use thrust washers each side of the bigend / cranshaft faces, but some Italian ones do not use them at all. The bigend eye bears against the crankshaft boss.

Are they necessary ?? what are the pros and cons ?? Also 1mm thickness seems a sensible minimum.

Information and comments please

thanks

Jennings will tell you why.
'
ps i posted it a while back as well. you obviously were not part of the exclusive 6 who actually read it.
Shame it had a pic something rather beautiful in it.:whistle:

[twotempi]

No, the conrod is not located laterally at the little end in the piston as is done in McCulloch chainsaw engines - and KT100 kart engines ??
It is located by the side bosses of the crankshaft without any washers although there are substantial oiling depressions in the side face of the conrods.

Jennings sayes that this may cause the oil to "flash off" thereby overheating the conrod bigend bearing.

This info is 30 years old now and I wondered if current experience has changed this opinion.

thanks for all replies as I have to make a decision for a crankshaft rebuild.

[husaberg]

No, the conrod is not located laterally at the little end in the piston as is done in McCulloch chainsaw engines - and KT100 kart engines ??
It is located by the side bosses of the crankshaft without any washers although there are substantial oiling dpressions in the side face of the conrods.

Jennings sayes that this may cause the oil to "flash off" thereby overheating the conrod bigend bearing.

This info is 30 years old now and I wondered if current experience has changed this opinion.

thanks for all replies as I have to make a decision for a crankshaft rebuild.

30 years old? I'd say closer to 40 years old;)

[wobbly]

Its the old story of simply moving the weakest link from one area within an engine to another.
Basic bearing operation dictates that full compliment needles will handle a heap of load, but are ultimately limited, in that the rollers are all rubbing on each other
and this leads to failure.They also cannot handle ANY movement away from dead true in any plane, as they then skid even more rapidly.
Having the big end well open with alot of clearance around the rod and cage helps access by the oil film and makes this area pretty bullet proof. with no washers in the way.
But this then moves the point of most wear up to the location washers in the piston.
In a KT100 the versions with alloy washers in the small end will have wear marks on these washers in a very short time, the small end being caged makes it bullet proof,and
the open rod big end lasts well, until the cage wears on the rod bore.
In the end it is the rod big end cage wear that forms the limiting factor, and it has been found by thousands of engine rebuilds, that the silver coated big end cage and washers have about the same ( acceptable ) limiting
lifespan - the open, caged small end lasts forever in either case.
Simply removing the washers is plain dumb - I have seen a couple of new crank designs done this way just recently, both failed very badly with lube failure around the rod big end - IT DOES NOT WORK, reliably.
Thus having the washers down the bottom becomes a known factor - replace them when you replace the cage.
The rod and pin will usually take around 4 bearing replacements.
Iin fact if you could buy them, simply replacing the cage ( with the washers as well ) would mean you could keep the rollers - for the life of the rod.

[twotempi]

Bigend thrust washers it is then !! Which was my preference.

thanks for the feedback.

[husaberg]

Its the old story of simply moving the weakest link from one area within an engine to another.
Basic bearing operation dictates that full compliment needles will handle a heap of load, but are ultimately limited, in that the rollers are all rubbing on each other
and this leads to failure.They also cannot handle ANY movement away from dead true in any plane, as they then skid even more rapidly.
Having the big end well open with alot of clearance around the rod and cage helps access by the oil film and makes this area pretty bullet proof. with no washers in the way.
But this then moves the point of most wear up to the location washers in the piston.
In a KT100 the versions with alloy washers in the small end will have wear marks on these washers in a very short time, the small end being caged makes it bullet proof,and
the open rod big end lasts well, until the cage wears on the rod bore.
In the end it is the rod big end cage wear that forms the limiting factor, and it has been found by thousands of engine rebuilds, that the silver coated big end cage and washers have about the same ( acceptable ) limiting
lifespan - the open, caged small end lasts forever in either case.
Simply removing the washers is plain dumb - I have seen a couple of new crank designs done this way just recently, both failed very badly with lube failure around the rod big end - IT DOES NOT WORK, reliably.
Thus having the washers down the bottom becomes a known factor - replace them when you replace the cage.
The rod and pin will usually take around 4 bearing replacements.
Iin fact if you could buy them, simply replacing the cage ( with the washers as well ) would mean you could keep the rollers - for the life of the rod.


I thought long and hard before i replied as i often agree with you (Because you are in fact far cleverer than I )
Yes it has to be engineered to have the thrust clearances maintained from the little end only.
But there a a few advantages one being the little end is easy to get to replace alter.
The other as you alluded to i guess is that stress are far less on the little end end.
Chasing the weakest link or limiting factor is I believe what any sort of engine development is about .
Yes The big end in most (if not all cases) can be made reliable for the stress buckets are under yes granted.
But the quality parts to accomplish this reliability are not always actually F4 and f5 class legal.
There are some parts that were used in road and non competition bikes or sold as size that will be legal but not in all sizes.
Just my opinion really not that it really maters because i still are procrastinating on my build and have ran in a bit of a problem.

[Yow Ling]

I thought long and hard before i replied as i often agree with you (Because you are in fact far cleverer than I )
Yes it has to be engineered to have the thrust clearances maintained from the little end only.
But there a a few advantages one being the little end is easy to get to replace alter.
The other as you alluded to i guess is that stress are far less on the little end end.
Chasing the weakest link or limiting factor is I believe what any sort of engine development is about .
Yes The big end in most (if not all cases) can be made reliable for the stress buckets are under yes granted.
But the quality parts to accomplish this reliability are not always actually F4 and f5 class legal.
There are some parts that were used in road and non competition bikes or sold as size that will be legal but not in all sizes.
Just my opinion really not that it really maters because i still are procrastinating on my build and have ran in a bit of a problem.

If you are going on about whether or not big end bearings are bucket legal then its probably a waste of breath.
When did a bucket ever get stripped to that level and who can tell if the bearings are legal or not.
When was the last time a bucket was pulled to bits for tech at all?

[husaberg]

If you are going on about whether or not big end bearings are bucket legal then its probably a waste of breath.
When did a bucket ever get stripped to that level and who can tell if the bearings are legal or not.
When was the last time a bucket was pulled to bits for tech at all?

Mike could tell and so could I. At least on a MB/H100. I also have a stack of Cr ones and it is easy to tell.


I've been looking for a good big end bearing for Gary's bike. Whilst at the kart shop I checked out a KT100 rod kit. Turns out the big end bearing is 26X20X13.8, EXACTLY the same as a MB100. Moral dilemna for a bit. They are a bit different to look at and I could spot one even if it was all assembled onto the crank/rod. Further research has come up with a same size bearing with a description that makes it similar design to the KT part. Moral dilemna over. It does mean if you wanted to build a cheater engine which handled 16,000rpm that the parts are available from your local kart shop.
Just in case anyone thinks I honestly thought for more than a second about using an illegal bearing, anyone is welcome to have a look inside my engine, or Gary's but you'd have to ask him about pulling his one apart.


True it would be real easy to cheat, but is i believe and so does Mike it is eminently more satisfying to remain legal. (I have always thought the bearing and rod rule to be rather silly myself though i should add)
What i was going to add to my post. i was rereading George Begg's Burt Munro book (for inspiration i guess)and was surprised how tiny his crank pin was before he finally got around to modifying it for positive lubrication. It was smaller than most buckets (admittedly very narrow as it had Knife and fork rods) yet took the force of at the time 90 odd horses with a hit and miss lubrication to boot. Yes i believe the rollers gave trouble more To do with heating due to lack of lube but it seems ,notehe also sweared by std genuine chamfered Indian rollers as well. not relevant but interesting

[wobbly]

Dont think it matters any more - a "suitable " legal rod can be found to work in just about any bucket application you would, or could,dream up.
Especially if you are prepared to modify the crank by spark eroding or eccentric bushes, or whatever.
And as there are several manufacturers that have a range of "off the shelf " silver plated big end cages ( generic types ) that are not specific
to any so called competition based engine, then I believe that this makes it impossible to enforce that long standing rule.

The KT100 has two types of rod location available, and the version with thrusts up the top has wear issues with these, maybe hard anodising ally washers would ameliorate this current problem.
But - the big end cage still ends up wearing out due to rubbing on the rod bore - despite the better access by the lube mist with no thrust washers.
Thus as I pointed out,the big end cage is the limiting factor to longevity, no matter what the mechanical setup is.
And as it has been proven in the field that the silver plated washers and the cage, have similar life span,then in my opinion there is no reason at all to not use this method.
The manufactures that dont are very much the odd people out now days amongst what we would call normal applications - there are a few other solutions used in small super high rpm race engines,
but these are overkill for anything only spinning to a paltry 14000.

[husaberg]

but these are overkill for anything only spinning to a paltry 14000.


i also read something interesting (1970's)which suggested a 2 vs four stroke comparison was approx
100cc vs 140-150cc using both volumetric and mechanical efficiency.
which suggests the MNZ rules are pretty close and a hell of a lot more equal than the AMA mandated rules of 144 vs 250 and 250 vs 450.

Also when is it worthwhile crossing to a twin cylinder. (I must admit it would be hard to match the simplicity and value money wise of a single though)
But what would be the ultimate cylinder size (within the rules for buckets) for ie where mechanical efficiency (for want of a better term) and volumetric efficiency meet.

I seem to remember Wob mentioning something about a 100cc twin would have to spin to something like 19000rpm to match the BMEP of a single 100cc pulling 14000rpm


The only way you would see any advantage running a twin is if you have the knowledge and wherewithall to build it properly.
This would mean running it to around 20,000 rpm to achieve a higher bmep than the single.
And as we already see in the 100 class, those engines dont rev as hard as the 125 GP single motors, when to see the advantage of a 50mm stroke the 100cc should be going to at least 14000 all day. - so basically, forget it.
A twin wont make as much "torque" but will make alot more "power" if done right.

But if its possible to build a 20 odd HP 50cc single that was only reving to 14000rpm why not a 40hp 100cc twin Is there a lot more losses somehow or is it all relative per cylinder?
I am certainly not doubting you wob, but only trying to get my head around it.
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=246908&stc=1&thumb=1&d=1316214030

Getting 20 from a 50 is easy, its all in the numbers,but its certainly not cheap..
If you have all the components working together in synergy then the STAs tell us it can be done.
Note how well every variable is right on the money - and as long as you implement every mod remembering that we are dealing with a "on the limit" scenario,then the numbers do translate into reality.
I have a KTM50 cylinder on its way from England for a customer now, the pics look like its very very well made.

[rgvbaz]

Husaburg,

I cant see the pic properly at the bottom of your post, It looks like the TA screen from Dat2T.

In terms of TA the twin 100cc should be able to have more than the 100cc single as 40 x 40 bore stroke (50.3 cc) has 5026.5 mm^2 wall area X by 2 cylinders gives a total of 10053mm^2 for the twin

A 50mm x 50mm bore stroke (100cc) has 7854 mm^2 total wall area for the single. 10053/7854 = 1.28 so the twin 100cc has 28% more wall area for ports! so should be able to support more TA.

I'm sure there is probably more to it

Cheers

Dave

[rgvbaz]

Just had a quick look at power potential for a given port area for a twin and a single. I happened to have a file for a 50cc twin so I used this for the study. It is purley based on STA that DAT2T calculates as a potential that could be achieved from a port. All of the figures are in hp.

For both engines I kept the timings the same 190/130 duration, both are square with the same conrod/stroke ratio. I used 70% of the bore for the flow width of the exhaust port for each cylinder and 70% again for each transfer flow width, there are 2 transfer ports in each cylinder.

Here is a graph of the power potential of the transfers and the exhaust blowdown. As you can see, even at the lower rpm, 13000rpm, the twin has the advantage in TA.

260295


Cheers

Dave

I should look at it again for different bore/stroke ratios.

[wobbly]

I wasnt saying at all that technically the 100cc twin was not capable.
What I am saying is that we have 100cc buckets making 30 Hp now, and they are only reving to 13,000 when in fact a 50mm stroke should be going to well over 14000 - thus making 40Hp a reality, if done " properly ".
Christ its taken 5 or more years for people to get that 30 Hp was easy - as I said to Nige and Mike so long ago.
Why would anything change when we go to a 40mm stroke with a twin, the chances of it being done " properly " are virtually nil, and where is the non competition close ratio box going to come from, let alone
cylinders that could be even remotely considered as being able to be modified to make decent power ( a fully modern KTM type 50cc cylinder with everything copied from Jan Thiel is needed to make 20 Hp ).
The twin will always be capable of alot more power - the know-how and mechanical/financial restraints have a much bigger part in this sports reality , than simply playing around in a simulator.

[husaberg]

I wasnt saying at all that technically the 100cc twin was not capable.
What I am saying is that we have 100cc buckets making 30 Hp now, and they are only reving to 13,000 when in fact a 50mm stroke should be going to well over 14000 - thus making 40Hp a reality, if done " properly ".
Christ its taken 5 or more years for people to get that 30 Hp was easy - as I said to Nige and Mike so long ago.
Why would anything change when we go to a 40mm stroke with a twin, the chances of it being done " properly " are virtually nil, and where is the non competition close ratio box going to come from, let alone
cylinders that could be even remotely considered as being able to be modified to make decent power ( a fully modern KTM type 50cc cylinder with everything copied from Jan Thiel is needed to make 20 Hp ).
The twin will always be capable of alot more power - the know-how and mechanical/financial restraints have a much bigger part in this sports reality , than simply playing around in a simulator.


Agreed while technically feasible it is cost prohibitive. The original question was more what is the optimal cylinder size for the bucket rules.
Although i was incredibly impressed when i picked up a complete KTM50 engine they are tiny and incredibly light (san gearbox admittedly) the pics are the old (beta Engine)New one is far sexier.
http://motomx.com/ktm50new/ktm50%20short%20block%20engine%201.jpghttp://motomx.com/ktm50new/ktm50%20short%20block%20engine%202.jpg
and bits for race 50's are incredibly cheap. but not my cup of tea with the extra complication of 2 of everything as well as twice the number of things to replace and modify build etc pay for etc.
But i did struggle to get my head around why the 100cc twin would have to rev to 20000rpm to do 40hp when the 50cc single was capable of 20 at 14000rpm?

Oh yeah Wob you mention eccentric bushes how are these made?
As it seems some engines have there mainshafts so close to the crankpins it makes the normal machining fraught.
I have also heard of the spark erosion (from you)I guess t is the same process used to remove studs or so forth?
With this method is it possible to for want of a better term drill the half offset hole without filling? is it cheaper than filling re drilling? w\
While on the subject is the filler material (used when the four stroke cranks are filled) stainless and why what sort of cost would be expected for each and pros and cons.Sorry long question lots of assumptions pos required as well so lets use this crank as an example.
It may look familar.:innocent:
It caught me by surprise as i certainly wasn't expecting Honda to change the spine and the mainshaft diameter from the NS125 vs NSR125 as well as the diameter of the crankwheels is a bit larger than i expected as well.(I guess to allow for the NSR150) for reference the pin is 24mm dia.
The last 2 pics are the 50.6mm stroke cylinder reed NS125 pics for reference.Bloody honda why change the spines method when you are normally so lazy.

[2T Institute]

The MBA 125 twin was the bike that forced the single cylinder rule in 125cc GP. A RD125 with it's 43mm stroke and using 39.5mm pistons from a range of Euro 50cc bikes with custom triple exhaust port Nicasil sleeves would be an awesome little machine.

[wobbly]

The problem lies with the fact that you need super sex technology to get 20 Hp from a 50 at "only "14000.
Its the short stroke of the 50, or for that matter a 100 twin, that is its inherent advantage - as we all know Hp = T * RPM/5252.
Thus double the rpm and you double the power - as long as you can hold up the torque at the level.
Without very good cylinder geometry, along with a PV then the only way to get some power, is to rev the shit out of it.
Then the power band width becomes progressively narrower, needing more, closely spaced gears to make it work.
Without most of the help of plenty of technology,the 100 twin in a Bucket scenario just becomes a screamer with no real advantages - hamstrung by its weight and lack of a close ratio gearbox.
Of course I would love to have a go at one, I had a TA125 in a sprint kart back in the day, and just loved the howl of the thing spinning to 16000,with a genuine factory close gear set.
Even if my poxy red cylindered air cooled Honda CR125 was faster.

Need to look closely at the Honda setup for you but the best way I think is to fill the top of the big 24mm pin hole, and use a much smaller pin - offset down to get the stroke needed.
For example 125 ICC kart engines all use 20mm pins, and they are dead reliable to 15000 - of course we need to find a legal rod eh.

[husaberg]

..Without most of the help of plenty of technology,the 100 twin in a Bucket scenario just becomes a screamer with no real advantages - hamstrung by its weight and lack of a close ratio gearbox.
Of course I would love to have a go at one, I had a TA125 in a sprint kart back in the day, and just loved the howl of the thing spinning to 16000,with a genuine factory close gear set.
Even if my poxy red cylindered air cooled Honda CR125 was faster.

Need to look closely at the Honda setup for you but the best way I think is to fill the top of the big 24mm pin hole, and use a much smaller pin - offset down to get the stroke needed.
For example 125 ICC kart engines all use 20mm pins, and they are dead reliable to 15000 - of course we need to find a legal rod eh.

All revs no action 2x everything to fiddle with adjust make pay for wear out faster too.The thought of two carbs to tune as well:sweatdrop

.,the 100 twin in a Bucket scenario just becomes a screamer with no real advantages -
there is a certain procreative advantage's to having a screamer, certainly to be preferred over the moaner i am saddled with anyway:confused:I know which one i prefer anyway.

The rod i think i have sussed. Name thy preferred length 104 or 105mm.
Whist on a net troll i came upon some some GP spec rods and i was surprised just how long the RSW and RSA Aprilia rods are.
I did notice however the Cagiva crankshaft is quite similar to the NSR125. Are those Europeans still copying the Japanese:innocent:
http://www.2rad-sausenthaler.de/WebRoot/Store17/Shops/61548808/4978/4B6F/4AE0/A246/E39A/C0A8/28B8/2B47/27_m.jpghttp://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=260305&stc=1&thumb=1&d=1332538911

[wobbly]

Was pissing down this morning so didnt make the trip to Taupo - went to Gingers place this arvo in Huntly to set up his new Ignitech on Bultaco 350.
Obviously will hear all about it here.

The Aprilias had around 2.2 rod/stroke ratio, with 50.6 stroke the closest rod would be around 110 long - still a little shorter ratio.

[twotempi]

Having a longer rod ratio - say the Aprilia at 2.2 - will decrease the difference of rotational speeds of the big-end bearing between TDC-Half Stroke-BTDC.

Example - If the rod was of infinite length the big-end bearing would constantly rotate at half crankshaft speed

So do longer rods have a significant benefit for the big-end bearing ??

[F5 Dave]

Was pissing down this morning so didnt make the trip to Taupo - went to Gingers place this arvo in Huntly to set up his new Ignitech on Bultaco 350.
Obviously will hear all about it here.. ..

Or over on the F4 picks thread. But suffice to say no one is blowing any trumpets of glory.:shutup: It could have all gone so differently.

[wobbly]

So are you guys telling me you cant tune your way out of a brown paper bag?
What happened.

[F5 Dave]

I can only talk for myself when I put my hand up for a couple of slightly unlucky mistakes aided by no time & no money atm. I'm also questioning my choice of piston (YZ100 std cast) as I can't seem to keep them together at a lowly 12k peak, 12.5 over rev. Looking at Wiseco forged, but they aren't a pretty piston. Heck this is my interim slap together engine with a 51mm compromise. I would have been happy to finish. I was more than happy with qualifying earlier on Saturday. But to finish first, first you have to start the soddin' race:facepalm:

Av's bike didn't make it to practice, Mike's bike showed promise with Dave on board,- well I'll let him tell the story.

3rd & 4th place on the grid were empty come the GP.

[richban]

So are you guys telling me you cant tune your way out of a brown paper bag?
What happened.

To much Dyno tuning not enough track tuning. It was a white wash. 4T. 1 2 3 4 5 6 7 8. Ok thats my only rub in coz I am genuinely gutted for the lads and Lady's.

[Rick 52]

So are you guys telling me you cant tune your way out of a brown paper bag?
What happened.
It was very strange ,all the bikes should have run rich but they didn't !
My main was spot on but lean on the pilot and rich on the needle
In the rain it was running brilliant but in the arvo it lost it's edge
I'm so pleased to have got home without being lapped even if it was only 300 mts away !

[TZ350]

I have to say congratulations to the 4-Stroke boys and particular Nick Cain for winning the GP and showing what riding the wheels off your bike looks like.

260431

James H for Second and Andrew A for third after starting from the back of the grid. And Richard Ban (4th) and Regan Griffiths (5th) on his Crazyman framed FXR.

Sure Team ESE and a lot of the other 2-Strokes got our Butts Kicked but off track the 4-Strokers were very social and did every thing they could to help us get out there, they are a great bunch and we enjoyed their company very much.

I thought we were going to pull it off this year, maybe even have all 2-Strokes on the Podium but as the Strokers faded away so did our thoughts of world domination.

But our hopes for at least a Stroker win in the GP were encouraged by the sight of Nathaniel mixing it at the front with Nick and then starting to open up a useful lead only to unseat himself climbing the hill on the infield, after that Nick had no real competition.

260432260433260434260435

The Pictures tell it all, The 2-Stroke Boys hard at it trying to keep in the game.

260436

While the 4-Strokes looked pretty calm.

[TZ350]

To much Dyno tuning not enough track tuning. It was a white wash. 4T. 1 2 3 4 5 6 7 8. Ok thats my only rub in coz I am genuinely gutted for the lads and Lady's.

True, to much dyno not enough track time ...... we just have not been able to get the track time needed to sort out the carb, the Beast has a problem coming back onto the throttle after shutting down for a corner.

So what happened to the the Beast at Taupo, well not sure yet. At Te Puke there was a considerable delay after throttling off before the engine came back on song. We changed to what we thought was a better needle for Taupo.

And Kel took it out in the first practice and lap one it seized when he throttled off at the end of the front straight. He came to a stop and it started again. Then going out onto the drag strip it seized again as he throttled of and started easily again after he came to a stop.

Back in the pits we changed to a richer needle and he went out in qualifying and it ran like a dream on full noise and it easily had the legs on anything he came across but it still had the throttling on again delay.

After the session he rode back to the pits and let the engine idle to a stop. After that we could not get it to go again, it looked like it had plenty of compression, there was fuel but the spark was orange and not the blue we expected.

A few pushes and we get backfiring out of the carb and exhaust. The suggestions are bad or fouled plug.

We tried two different new plugs and the spark was still orange, changed the coil and CDI, and the spark was still yellow/orange. Speedpro lent us his special old faithfull plug and then we got a blue spark.

A few pushes and we still get backfiring out of the carb and exhaust. The suggestions are now, the ignition has slipped. So off with the flywheel to check the key, all is ok there.

Now we were lucky that Brent had a timing light and sure the timing looked out, so we were double lucky that Brent also had his laptop and Igntech software so we could look at the setup and try a few things.

Pretty much everyone pitched in and helped but nothing we did made any difference.

So of to have a bit more of a look tonight.

[F5 Dave]

I forgot you took that picture. Don't know why I'm smiling like a loon, - perhaps it is the moment I have just encouraged the ring out of the groove & think I have a chance of getting back in the game, but before I noticed the small piston crack. My bike looks like a total junker next to Brents.:shutup:

[TZ350]

Ok just draged the Beast out of the shed, looks like the good compression and colour of the spark at Taupo was a Red Hearing as there is no compression now.

[F5 Dave]

That would be 4 strokers with piston/ring damage. Don't look at me, I didn't jet down.

[TZ350]

Ok just draged the Beast out of the shed ... there is no compression now.

260438

Oooops no plug ....... :laugh:

I was sure it had plenty of compression at Taupo, anyway got a comp tester onto it and there is 90 psi, enough to feel like plenty when pulling it over on the back wheel but way short of the 160 it was built with.

[F5 Dave]

well I finger wound a plug back into it to stop the rain getting in. Or maybe you had to give that one back to Mike.

[Buckets4Me]

260438

Oooops no plug ....... :laugh:

I was sure it had plenty of compression at Taupo, anyway got a comp tester onto it and there is 90 psi, enough to feel like plenty when pulling it over on the back wheel but way short of the 160 it was built with.

come on pull the head off and show us the piston :innocent:

[TZ350]

well I finger wound a plug back into it to stop the rain getting in. Or maybe you had to give that one back to Mike.

Gave that one back to Mike, I guess I didn't put another one in for the trip home.

260446260447260448

There is the naughty little sausage, with the ring jammed at the exhaust port.

This must have happened in practice when it seized, amazing the thing ran so well in qualifying, it was still doing a good turn of speed and zipping most things in sight, I guess it just didnt want to go back out there for the main event.

[richban]

Could it be as simple as the main jet to lean. I know on my bike it was super hard to setup a main on a kart track. I did most of mine on manfield. And plug chopped after 20 seconds of full throttle. Was the new needle lean or richer on the taper? Might be why it works on the kart track and not the big track. never on the main for more than a few seconds. Just a thought. Well at least in my video there are two 2 strokes for a while.

[TZ350]

Could it be as simple as the main jet to lean.

Not sure, but I did go up a jet size before practice just for safety, we fitted a new plug for qualifying and a reading, the plug looked good. I will know more when I get the piston off and have a look at the underside of the piston crown.

[twotempi]

A mere flesh wound ??

[TZ350]

A mere flesh wound ??

260461

Yes a mere flesh wound ...... up and running in no time.

[Frits Overmars]

If the rod was of infinite length the big-end bearing would constantly rotate at half crankshaft speed
So the small end would sweep around at the other half of the crankshaft speed? I hope not...
OK, the big end bearing cage would constantly rotate at half crankshaft speed. Which is a good thing.

So do longer rods have a significant benefit for the big-end bearing ??Yes. Long rods may be heavier, but load is not what kills a big end. It's the rotation speed fluctuation and the crowding of the needles towards the outer side af the crank that cause skidding, friction, heat, destruction of the oil and same of the bearing.

[bucketracer]

Maximum output of a 50cc engine using "todays technology"!

260472

The expert:
"The best horsepower we attained at Aprilia last year (2007 125cc GP) was 53,9 HP at 13000 rpm. This means a Pme of 14.88 at a piston speed of 23,6 m/sec. Using these same values means that a single cilinder 50cc would give 29.5 HP at 17850 rpm and a 50cc twin would give 39 HP at 23600 rpm, measured at the gearbox output shaft. I am 100% sure these values can be attained although it never will be proved due to lack of interest and money. Remember that 50cc development was stopped in 1983 and enormous progress was made in the following 24 years. Now, sadly, also the development of the 125cc two strokes has stopped, the two stroke will only survive in karting but there will be no progress because of the very strict regulations!"
Jan Thiel 2008
http://www.elsberg-tuning.dk/engineering.html#theengine

[Frits Overmars]

Oooops no plug ... I was sure it had plenty of compression at Taupo, anyway got a comp tester onto it ....260438
I hope you didn't measure the compression with the plug cap lying around like this; that would be a great way to fry the ignition. If the high tension cannot find a way out via the plug gap, it will create its own shortcut escape route inside the ignition unit.
Every engine I work at has a protruding M6 bolt somewhere, where I park the plug cap every time it is not on the plug.

[bucketracer]

260438Every engine I work at has a protruding M6 bolt somewhere, where I park the plug cap every time it is not on the plug.

Good idea ..... thanks.

[SS90]

Gave that one back to Mike, I guess I didn't put another one in for the trip home.

[ATTACH=CONFIG]260446

There is the naughty little sausage, with the ring jammed at the exhaust port.

This must have happened in practice when it seized, amazing the thing ran so well in qualifying, it was still doing a good turn of speed and zipping most things in sight, I guess it just didnt want to go back out there for the main event.

From the looks of the first image, it looks like there are witness marks on the crown (sharp edges), suggesting the piston was touching the head, causing the ring to jam.

Any chance that was the culprit?

[TZ350]

260438
I hope you didn't measure the compression with the plug cap lying around like this; that would be a great way to fry the ignition. If the high tension cannot find a way out via the plug gap, it will create its own shortcut escape route inside the ignition unit.
Every engine I work at has a protruding M6 bolt somewhere, where I park the plug cap every time it is not on the plug.

No I didn't comp test it like that but did give it a vigorous shove trying to start it before realising, lets hope that there is a zenor or some sort of clamp set up that limits the maximum voltage that can be applied across the internal CDI circuitry by the back EMF of the coil. I like the stud idea and will fit one.

[wobbly]

The only things that fry these digital CDI units is input overvoltage, caused usually by idiots that run a regulator direct into the ECU with no battery or capacitor load.
I got Ignitech to stop this with a Zener and detector circuit that shuts the ECU down.
But the second death of spinning the motor over without a plug, it is very difficult to prevent damage almost instantly with around 40K running around looking for a random earth - it
usually finds it thru the side of the CDI cap.

[marsheng]

Just found this - BEMP figures !!!!

'Here in Brazil our preferred engine for drag racing is the VW ABA 4cyl 2.0 Liters and I've got 1180 Hp on this little sport compact machine with just 3.6 bar intake pressure.'

Well maybe it's time to revisit a 100cc and supercharger.

[wobbly]

Shit - ONLY 54 lbs of boost, I can fart harder than that.

[Yow Ling]

Just found this - BEMP figures !!!!

'Here in Brazil our preferred engine for drag racing is the VW ABA 4cyl 2.0 Liters and I've got 1180 Hp on this little sport compact machine with just 3.6 bar intake pressure.'

Well maybe it's time to revisit a 100cc and supercharger.

Good idea, that should keep you busy for a while !

[TZ350]

260502

The sized piston from the Taupo GP.

260499

On over rev, close but not touching.

260501

Not so hot that it has coloured the underside of the piston crown, so not overheated. My pick is it needs a touch more clearance.

260500

I think that the top edge and ring grove have been pushed up by the lower edge of the exhaust port, or hammered in as the piston rockes over and slaps the cylinder wall.

260504

The Honda RS piston shows some of the same signs too.

260498

This new Yamaha 90-93 YZ125 piston has a grove under the ring land. Whether that is to over come the ring jamming problem or for something else I am not sure.

[husaberg]

Just found this - BEMP figures !!!!

'Here in Brazil our preferred engine for drag racing is the VW ABA 4cyl 2.0 Liters and I've got 1180 Hp on this little sport compact machine with just 3.6 bar intake pressure.'

Well maybe it's time to revisit a 100cc and supercharger.
I bar 14.7 psi as Wob said 53psi not a problem unless Avgas is the fuel and inlet temps are anything that would be expected normal.
22psi could happen with an approx 6.5:1 comp ratio though a realistic figure for Avgas and efficient intercooling water injection and a Rootes blower. More boost possible with screw or centrifugal charger.(they don't heat the charge so much) But they wont offer such a linear boost to revs curve. ie they offer less down low too much up high.
If you seriously want to have a go i have 2x donor engines here (FZR250's) you can play with for what i paid for them.
If it could be engineered to stay together 40-45HP could happen, given enough time skill and and $.

In hindsight maybe the 50mm Cr80 piston has a lower pin than the nsr125 as well so maybe a couple of mm there too, to be gained.


Having a longer rod ratio - say the Aprilia at 2.2 - will decrease the difference of rotational speeds of the big-end bearing between TDC-Half Stroke-BTDC.

Example - If the rod was of infinite length the big-end bearing would constantly rotate at half crankshaft speed

So do longer rods have a significant benefit for the big-end bearing ??

Unfortunately my budget won't stretch to an infinitely long rod either.

But i did find the odd extra long one but with a 24mm pin as Wob said lots of 20mm pin ones go to 110mm But not sure how to accomidate without scewing up the rest of the engine clearances i would have thought around 106-108 would be easily doable though as well as allowing for the decrease in stroke. But wob will know how to fit them in and still make it work i guess.
I assume the decrease in stroke will make the port timing more racy and the Longer rod will increase the port time area as well?

In hindsight maybe the 50mm Wiseco CR80 piston has a higher placed gudgeon pin? so maybe a couple of mill there as well?

[speedpro]

260508260509260510

[TZ350]

..... 22psi could happen with an approx 6.5:1 comp ratio though a realistic figure for Avgas and efficient intercooling water injection and a Rootes blower.....If it could be engineered to stay together 40-45HP could happen, given enough time skill and and $.

A supercharged 100 has been an idea of mine for a while. I have been thinking of a Honda SL/XL/CB100 base engine with a XL185 or 200 cylinder and head.

The cylinder would be sleeved back with a wasted and "O" ringed Nickosil alloy liner and a jacket welded around the head fins for water cooling.

The supercharger would be independently driven and feed a large plenum, with fuel injection and digital ignition.

With the increased manifold pressure the engine would pull from down low and still rev right out on mild cams.

[marsheng]

260508260509260510

What am I looking at ?

[Yow Ling]

A supercharged 100 has been an idea of mine for a while. I have been thinking of a Honda SL/XL/CB100 base engine with a XL185 or 200 cylinder and head.

The cylinder would be sleeved back with a wasted and "O" ringed Nickosil alloy liner and a jacket welded around the head fins for water cooling.

The supercharger would be independently driven and feed a large plenum, with fuel injection and digital ignition.

With the increased manifold pressure the engine would pull from down low and still rev right out on mild cams.

Would this suit the independently driven criteria?
http://books.google.co.nz/books?id=UtxI5gXM1yQC&pg=PA526&lpg=PA526&dq=hyperbar+combustion&source=bl&ots=vVQRcxbEMO&sig=YjMWA8bk63z4NK_oV99eC2JQ48A&hl=en&sa=X&ei=-2VxT_niKoyyiQf1_LnkDw&ved=0CCMQ6AEwAA#v=onepage&q=hyperbar%20combustion&f=false

[Grumph]

What am I looking at ?

It would appear to be a two cylinder 125/250 yamaha....

As far as your independently driven blower goes, can i suggest that it be driven by oh, say, a 125 air cooled two stroke motor which you may just have lying around doing nothing....but it would have to be a bit more reliable.

Oh dear - we've come this far down this thread and here's the original poster revealing a fall back position consisting of building a FOUR STROKE.....

[Buckets4Me]

Oh dear - we've come this far down this thread and here's the original poster revealing a fall back position consisting of building a FOUR STROKE.....

thats his side chair project :shit: so many plans so little time

there was also talk of a 150cc 4 stroke at one stage twincam 4 valve 6 speed

but all this will have to wait till the gp is devloped into a reliable bike again (mine is 6 years old and still going)

[husaberg]

What am I looking at ?
A computer monitor screen?:confused:A assortment of Pixels?The picture of Miranda Kerr? Speedpros pics of his half an FZR? The mock up i did when i was bored. All of the above?

[husaberg]

A supercharged 100 has been an idea of mine for a while. I have been thinking of a Honda SL/XL/CB100 base engine with a XL185 or 200 cylinder and head.

The cylinder would be sleeved back with a wasted and "O" ringed Nickosil alloy liner and a jacket welded around the head fins for water cooling.

The supercharger would be independently driven and feed a large plenum, with fuel injection and digital ignition.

With the increased manifold pressure the engine would pull from down low and still rev right out on mild cams.

PS with a pitot tube CV carbs will work, they are clever like that. Not as good as EFI but doable blowthrough.

This is the Tramontana (attached below)
Russell Savory (Weird i always thought it was Savoy) RS developments.
I do have another article pretty much the same Cathcart was a but of a story whore like that.:shutup:
I remember an article on a superchargered Manx norton in a 500cc Cooper. It had from memory a 6 foot long inlet to serve as a plenum.

Anyway back to 2 strokes
Can you see Wob what the diff is between the gudgeon height on the CR80 50mm piston and the std NSR is?
i had a look and it looked like it was nearly 6mm surely not?



Wössner Forged piston fitting Honda NSR & CRM 125R 1991-2003
The flask is available in five sizes, from standard to maximum TDC.
53.94 53.95 53.96 54.44 54.94 mm.
Height total of 64.40 mm.
Height to the piston edge 62.00 mm
Center piston pin to piston top edge of 30.00 mm.
Center piston pin to the lower piston edge 32.00
Piston Bolt Dimensions 16 x 45 mm.
Two chromemolyringar height of 1 mm.
Piston Ring Locking at 5 o'clock and 7th
http://www.pvlsverige.se/vrm/kolvar/8019DA.jpg

Cannon Piston for Honda CR-80 Years 86-02.
The piston comes in two tolerances for bore 46 mm.
Fitting 79 cc engine.
Overall Height 53.25 mm.
Height to the piston edge 51.10 mm.
Center piston pin piston top edge of 24.10 mm.
Center piston pin lower piston edge 27.00 mm.
A piston ring chrome molybdenum 1.00 mm
Piston ring lock 150 degrees from the exhaust port at 5 am.
Piston Bolt 14 x 38.90 mm.
http://www.pvlsverige.se/vrm/kolvar/Proxkolv46.jpg

[2T Institute]

260502

The sized piston from the Taupo GP.

260499

On over rev, close but not touching.

260501

Not so hot that it has coloured the underside of the piston crown, so not overheated. My pick is it needs a touch more clearance.

260500

I think that the top edge and ring grove have been pushed up by the lower edge of the exhaust port, or hammered in as the piston rockes over and slaps the cylinder wall.

260504

The Honda RS piston shows some of the same signs too.

260498

This new Yamaha 90-93 YZ125 piston has a grove under the ring land. Whether that is to over come the ring jamming problem or for something else I am not sure.

I see the piston has the old Wiseco logo (a W in a oval) I always bake these at 200deg C before the cylinders rebored or honed. Whilst not the best heat cycling better to find out if they are going to grow then than in the cylinder. They have a bad reputation for that. The later pistons appear to be fine(with the square logo on the box). RS125 manual recommends to V the ring groove in front of the exhaust port to stop the stuck ring problem. The 0.7mm ring fixes that better than the V.

[dinamik2t]

Wössner Forged piston fitting Honda NSR & CRM 125R 1991-2003
Height total of 64.40 mm.
Height to the piston edge 62.00 mm
Center piston pin to piston top edge of 30.00 mm.


Cannon Piston for Honda CR-80 Years 86-02.
Height to the piston edge 51.10 mm.
Center piston pin piston top edge of 24.10 mm


I think that when undersizing the bore with a smaller piston, the number you should pay more attention to is the overall height. While you can rise piston position into the cylinder with a longer rod and/or base plate, if total H is less than the distance from deck to ex. floor (stroke+deck?), then ... :mobile: Houston, we have a problem!

[husaberg]

I think that when undersizing the bore with a smaller piston, the number you should pay more attention to is the overall height. While you can rise piston position into the cylinder with a longer rod and/or base plate, if total H is less than the distance from deck to ex. floor (stroke+deck?), then ... :mobile: Houston, we have a problem!
Destroke as well as debore remenber i haven't got to the skirt yet.is that what you are meaning? total h? but yeah big diff there. but the cr ran a fairly long stroke.

[wobbly]

The +3mm CR85 pistons I have here are just over 51mm skirt ( so fine for a 50.6 stroke ) with a 24mm pin bore to timing edge.
Gives plenty of room for the long rod.

[teriks]

Just found this - BEMP figures !!!!

'Here in Brazil our preferred engine for drag racing is the VW ABA 4cyl 2.0 Liters and I've got 1180 Hp on this little sport compact machine with just 3.6 bar intake pressure.'

Well maybe it's time to revisit a 100cc and supercharger.
How about a single cylinder of a BRM V16? Ends up at ~94cc and around 37hp at 12kRPM and 5.7bar boost, should be cheap end dead reliable :P
One of few four-stroke engine noices that can compete with a full blown two-stroke in my ears: http://gpl.krej.cz/mp3.html

[F5 Dave]

oh well, 1/2 your luck TZ. I found cracks on the underside of the piston on both guneon pin bosses.

Also the thrust washer on one side of the crank has a bend in it?!? Not sure how that happened! Hmm, maybe when the last piston exploded & I didn't notice (or look that closely it has to be said).

[jasonu]

260508260509260510

Coor Mike, that old chestnut...

[TZ350]

260590

Measured up the cylinder and sized piston.

Old sized piston has 0.006"clearance new piston has 0.003" as per Wiseco recomendations.

The old piston also had 0.003" clearance when it started out.

260591

Even though the underside of the crown is not showing signs of overheating there is some thought that 34 crank hp may be more than the thermal limit of the air cooled GP engine.

Anyway I have been talking with the ex ACL engine man and he wan'ts to see some pictures.

260589

Not to hard to clean the alloy off the bore.

[husaberg]

The +3mm CR85 pistons I have here are just over 51mm skirt ( so fine for a 50.6 stroke ) with a 24mm pin bore to timing edge.
Gives plenty of room for the long rod.

So that leaves 27 mm center of wrist pin to end of skirt. within 1 mm of the std NSR125:woohoo:If you allow for the stoke as wob said.(But Vanessa will indeed have a fairly short skirt)


In hindsight maybe the 50mm Cr80 piston has a lower pin than the nsr125 as well so maybe a couple of mm there too, to be gained.
Unfortunately my budget won't stretch to an infinitely long rod either.

But i did find the odd extra long one but with a 24mm pin as Wob said lots of 20mm pin ones go to 110mm But not sure how to accommodate without screwing up the rest of the engine clearances i would have thought around 106-108 would be easily doable though as well as allowing for the decrease in stroke. But wob will know how to fit them in and still make it work i guess.
I assume the decrease in stroke will make the port timing more racy and the Longer rod will increase the port time area as well?

In hindsight maybe the 50mm Wiseco CR80 piston has a higher placed gudgeon pin? so maybe a couple of mill there as well?

Were any of my assumptions correct? Broadly speaking.

Turns out nearly 6mm diff in between Cr80 plus 3mm piston and NSR125 piston or so in pin location to top of piston outside edge.

So if a std nsr rod is 104mm center to center.

I intend to loose 4mm stroke so that's 2mm up.(and 2mm down or so)

So a center to center rod length of arround 112mm rod would be close to the ideal number required.
Which would also give a rod ratio of 2.21:1. Similar to the Aprilia RSA125.(Pos not available so 110mm will likely have to do)

Although all of these changes will reduce the primary comp ratio i guess.

Therefor Vanessa will likely have some big lungs on her then:drool:

Some stuffing may be in order? (Implants to enhance her curves?)

Does that mean it would be better to start with a smaller id Crank and stuff the whole case?

[wobbly]

Its of no importance really where the cylinder sits once its all mocked up, a spacer plate a couple of gaskets and we can move it around to get whatever we want.
Then cut the case/cylinder and fill with Devcon as needed to get good flow from the reedbox as well as the correct vol.
So broadly we need a small big end pin at around 20, 110 centres with 14mm small end - get looking.
I have just done a Pavesi 144 rotary valve that ended up with a 6mm lasered spacer,with its new long rod and oversize KX125 piston the case vol ended up at 1.26, getting close to the RSA.

[husaberg]

Its of no importance really where the cylinder sits once its all mocked up, a spacer plate a couple of gaskets and we can move it around to get whatever we want.
Then cut the case/cylinder and fill with Devcon as needed to get good flow from the reedbox as well as the correct vol.
So broadly we need a small big end pin at around 20, 110 centres with 14mm small end - get looking.
I have just done a Pavesi 144 rotary valve that ended up with a 6mm lasered spacer,with its new long rod and oversize KX125 piston the case vol ended up at 1.26, getting close to the RSA.

Found 3 of them?:woohoo:

There were others but i consider a 18mm od on the small end to be a better bet as there is more small ends bearings available with superior cage designs.

What next:msn-wink:

[wobbly]

What width - the same as the existing rod would be perfect, what are they from??.
Get one and I can start modding the crank.
We can skim the crank OD if needed for vol, as the short stroke will move the pin hole away from the outside.

[husaberg]

What width - the same as the existing rod would be perfect, what are they from??.
We can skim the crank OD if needed for vol, as the short stroke will move the pin hole away from the outside.

will pm you as they are unique and rods are always top secret.

But they may Spanish or Italian i can never tell the difference.
It could even be Asian as well.

[Frits Overmars]

.....there is some thought that 34 crank hp may be more than the thermal limit of the air cooled GP engine.260589To me it is shocking surprising to see the words air cooled and GP engine in the same sentence :p.
Do I see a single exhaust port there? I can hardly imagine the blowdown time.area will allow for more than 9000 rpm. That means: any more revs and the hot exhaust gases will blow down into the transfer ducts, heating up the cylinder quite effectively. If that is the case, not even water cooling would give you reliability.

[bucketracer]

To me it is shocking surprising to see the words air cooled and GP engine in the same sentence :p.

"1978 Air Cooled Suzuki GP125" calling it a GP, I guess is another example of the advertising copy writers enthusiasm for the company's product, in their defense the GP is loosely based on the single cylinder air cooled rotary valved Suzuki GP racing bikes of the 60's. Although TeeZee is getting more hP out of his than Suzuki did from their air cooled rotary valved racers of the time and they probably had a bigger R&D staff and more than one dyno.

[husaberg]

He does have the tripple port in reserve did you end up running the wobbly pipe?

Out of interest and seeing as i don't like secrets as it not the idea of the thread.
the ubiquitous Suzuki Bloop (B120) not sure if they were imported into NZ can't recall ever seeing one here.
but Suzuki sold millions of them they were almost the same mold of bike as the H100 only uglier. (Basic no frills commuter)
It does however have rod dimensions that would seem perfect for Vanessa other than being a fraction wide +1mm in the big end but as the std Honda washers are rather thick it could actually be made to work.
Yes the std bearings wont be up to much, but are common sizes.
Yeah the pin is wrong length as well. Who thought it would be easy.
Another Suzuki Gt250A/M also looks like it could also work as seems to be the same dimensions.(Below) it's Actually same conrod part number. TKRJ.

But there must be heaps of rods from Zundaps,Sachs, DKW's and minerilis Rotax's etc (Non Comp) that are not listed anywhere i know of that could suit as well anyone?


Oh Frits
can you please confirm, assuming it 's not a trade secret who actually made the Aprilia race rods.What sort of quality is Samarin's rods and bearings as well?
the aprilia rods would seemingly fit as well. I believe they are 20mm pin and 19mm little end do you have any lying about:whistle::whistle:
Were those Aprilias non competition engines:innocent:

[Frits Overmars]

It's not a trade secret any more, but I always tried to keep as far away as possible from commercial affairs, so I simply don't know who made the RSA rods; I only know the material came from France.
Samarin rods and bearings seem to be OK; they are widely used in 50 cc racers and do not give any problems there.

The Aprilia RSW rods had a 20 mm big end pin, a 15 mm piston pin and a center to center length of 115 mm. The RSA rods had a 24 mm big end pin, a 15 mm piston pin and 120 mm c--c length. But all this may have changed; after Jan Thiel went into retirement, several Aprilia people seized the opportunity to try their own ideas (like fixing alloy disks to the inside of the crank webs to decrease the crankcase volume). It's no secret that the RSA's were not as fast in 2011 as they were in 2007....

Sure, those Aprilias were non-competition engines. They were only used for a sunday afternoon stroll around a nice stretch of road that happened to be closed to other traffic :whistle:.

[bucketracer]

He does have the tripple port in reserve did you end up running the wobbly pipe?

The plan is, Wobbly pipe and tripple port and maybe even a re visit with the plenum on the dyno after Kaitoke at Easter. I think there is a complete new engine on the drawing board, mostly about improved cooling and a plated alloy tripple port liner for better ring life. TeeZee is keen to get on with developing power spread from the engine and is frustrated that it takes so long to get things done.

[wobbly]

Here is the STA output of the file that was used to sim the single Ex port GP125.
It shows that at the outer limits of width and timing, with perfect port geometry, a top notch pipe etc the system is capable of 40 CHp,on Avgas.
The bmep and the rpm are all achievable,and believable, for an air cooled 125 bucket engine.
With imperfect ports, a Honda pipe and a 24mm carb the thing made 31RWHp, say 34CHp,so as always the dyno and the sim dont lie.

[F5 Dave]

. . .
the ubiquitous Suzuki Bloop (B120) not sure if they were imported into NZ can't recall ever seeing one here.
but Suzuki sold millions of them they were almost the same mold of bike as the H100 only uglier. . .
Yeah, there were heaps, no brakes, no power. A mate had one for years. & was you're mouth out with Soap. the H100 would roast the B120.
I do know Jimmy was running one the the rods in his Discvalve Kawi. But who knows how much metal they put in a rod meant to jold back 6 hp?

[twotempi]

"Sure, those Aprilias were non-competition engines. They were only used for a sunday afternoon stroll around a nice stretch of road that happened to be closed to other traffic ."


Nice one Frits

And I bet they never carried a pillion passenger on Sundays either !!

[twotempi]

A question for the technical gurus !!

What would be regarded as the minimum clearance for the crank webs inside the crankcase cavity so there is a minimum of viscous drag between the two items ??

1mm, 2mm or what ?

[Frits Overmars]

"Sure, those Aprilias were non-competition engines. They were only used for a sunday afternoon stroll around a nice stretch of road that happened to be closed to other traffic ."
Nice one Frits
And I bet they never carried a pillion passenger on Sundays either !!If I were to try hard enough, I might even find a picture of an Aprilia rider giving a fellow rider with a broken down Honda or KTM a lift back to the pits :D.

[Frits Overmars]

What would be regarded as the minimum clearance for the crank webs inside the crankcase cavity so there is a minimum of viscous drag between the two items ?? 1mm, 2mm or what ?1 mm should be enough to avoid the viscous drag.

[Frits Overmars]

Here is the STA output of the file that was used to sim the single Ex port GP125. It shows that at the outer limits of width and timing, with perfect port geometry, a top notch pipe etc the system is capable of 40 CHp,on Avgas. The bmep and the rpm are all achievable,and believable, for an air cooled 125 bucket engine. With imperfect ports, a Honda pipe and a 24mm carb the thing made 31RWHp, say 34CHp,so as always the dyno and the sim dont lie.Wob, I assume you are reacting to my remark" I can hardly imagine the blowdown time.area will allow for more than 9000 rpm. That means: any more revs and the hot exhaust gases will blow down into the transfer ducts".
Vannik's EngMod2T sim calculates the mass of fresh charge that can make it into the cylinder through the fraction of the transfer STA that remains available after the blowdown phase has ended. And I think EngMod2T is an excellent design tool. But I use a different approach: my sim calculates the blowdown STA that is required if you want to avoid any exhaust gas entering the transfers.
Your screenshot shows a BMEP of 11.4 bar @ 12,500 rpm. That is, like you say, achievable and believable. The Aprilia RSA also develops its maximum BMEP at about 12,500 rpm, but its value is almost 50% higher. You cannot keep an engine like that thermally sound if you allow any exhaust gas to heat up the cylinder, hence the different starting point in my STA calculations.
Granted, if the engine produces less power, you may get away with some blowdown into the transfer ducts. I merely tried to indicate that you can combat cooling problems by paying attention to the blowdown STA.

[Frits Overmars]

It has been a very long time since I experimented with Gordon Blair's originial EngMod program and I have no hands-on experience with Vannik's latest development, so maybe I am stating the obvious. But I think it could be interesting to investigate how a sim handles blowdown time.area.

In a real engine the exhaust gas defines how much time.area it needs to leave the building. If the transfer ports open before the cylinder pressure has fallen below the scavenging pressure, the exhaust gas will regard those open transfers as yet another set of exhaust ports and it will enter the transfer ducts. That will steal some of the transfer time.area.
Then, when the cylinder pressure has dropped sufficiently, those exhaust gases have to be expelled from the transfer ducts; that steals some more transfer time.area before the real transfer of fresh charge can commence.
So when an engine revs too high for the available blowdown time.area, it is the remaining available transfer time.area that suffers doubly. That is also the reason that power drops rather steeply past its maximum.

Now a sim must calculate the necessary blowdown TA and subsequently it can either calculate the remaining transfer TA, or it can calculate the total transfer TA and take into account that transfer can only start once the pressure ratio from transfers to cylinder is > 1 and that any exhaust gas must be washed out of the transfer ducts before fresh charge can start its journey into the cylinder.

It all boils down to this: if you reduce the exhaust timing or exhaust port width in a sim, does that result in a decreasing transfer time.area? Please let me know.

[wobbly]

The raw numbers as presented in the STA calculations take no account of possible backflow issues with insufficient blowdown.
All that is reported is the ability ( or otherwise ) of the entered port and timing geometry to make "X " amount of power.
Obviously it is up to the practitioner to ensure that the relationships between the various STAs for each port set will work synergistically.
As we have discussed on other forums the Blow STA is all important - but the Trans STA must also reflect the port/duct geometries ability ie its CD - to flow air to the level expected.
ie a port as described to the sim may be capable of say 50 Hp, but if it has a parallel sided duct with no inner radius then one must spec a much higher Hp port for it to actually flow enough
to achieve the desired amount in reality.

The sim on the other hand fully accounts for the differential across the transfer port,be this + or - to create inflow or outflow.The only issue that it cannot deal with is the scavenging pattern changes
created by blowdown affecting the first port to open,causing this staggered high port to flow last.
We can describe the general effects by changing the scavenging model input, but changing the timing of one port,is only seen as a change in area/timing, and thus a change in the blowdowns effect on flow - not as a change in scavenging efficiency.
Thus the sim uses the bulk flow created by the pressure ratio conditions,and all of the inflow/outflow and pressure differentials are shown during the sim running and any can be plotted in post analysis as needed.
Neels can add more to this if he feels the need.

Re the GP125 sim, I was alluding to the fact that I pushed the single Ex port scenario to its limits with as wide and as high timings as I dared go,then matched the transfer capabilities to this.
The closer the cylinder gets to having optimum transfer geometry, with the numbers shown in the STA file,then the closer it will come to meeting those theoretical upper limits.
Right now, I would suggest that the correlation is very very good,when you look at the mechanical parts and the limitations set by the 24mm carb.
It was the raw STA numbers that pointed the direction to go - and the sim proved it was possible.
On the dyno it went from 28 to 31 Hp by following the sims lead - now all it needs is more port duct massage, and a good pipe.
The limiting factor in the STAs is the intake - it says around 37 CHp, so Im sure if the other improvements are made, it can make the rear wheel of around 33 RWHp this implies.

One thing that cannot be quantified is how much the heating effect of the blowdown reverse flow is able to be dissipated by the cooling fins.Rob says it was fine at 28 Hp.
Only way to see if the engine is now on the limit is to thrash it do death on the dyno, emulating as far as possible the air flow regime with a fan, and see if the power fades dramatically.
A direct drive KT100 will fade 3 Hp in 18 after 4 pulls from 6,000 to 16,000 in 9 secs,change the pipe and loose a couple of that peak Hp and you can run all day with no fade at all, but still see the same 620C on the egt.

[TZ350]

Do I see a single exhaust port there? I can hardly imagine the blowdown time.area will allow for more than 9000 rpm. That means: any more revs and the hot exhaust gases will blow down into the transfer ducts, heating up the cylinder quite effectively. If that is the case, not even water cooling would give you reliability.

Thats very interesting, I have been looking at what you and Wob have had to say, plenty of food for thought there.


The raw numbers as presented in the STA calculations take no account of possible backflow issues with insufficient blowdown.
All that is reported is the ability ( or otherwise ) of the entered port and timing geometry to make "X " amount of power.
Obviously it is up to the practitioner to ensure that the relationships between the various STAs for each port set will work synergistically. As we have discussed on other forums the Blow STA is all important -

The engines STA's, exhaust port and 31rwhp graph

[F5 Dave]

Ooeer that's a very big square one (said the bishop to the hermaphrodite:mellow:).

[TZ350]

Ooeer that's a very big square one (said the bishop to the hermaphrodite:mellow:).

Did you notice the devcon in the front transfers to get the roof angle and timing right?

[husaberg]

Yeah, there were heaps, no brakes, no power. A mate had one for years. & was you're mouth out with Soap. the H100 would roast the B120.
I do know Jimmy was running one the the rods in his Discvalve Kawi. But who knows how much metal they put in a rod meant to jold back 6 hp?

Question One. "Was running is not confidence inspiring start"

Question Two Who is Jimmy?

Question Three the Honda rod you are running was designed to hold 11hp and there is i believe a modded one that only dynos this now.

The GT250a/m has a little bit more (with the same rod) than 12hp/cylinder so i guess they may have over engineered it a bit in reserve anyway. (I bloody hope so)
http://www.tkrj.co.jp/img/goods/BS0200B-11001_img_a_115840.JPGhttp://www.pvlsverige.se/vrm/Vevstakar/AP-230-ECM.jpghttp://www.tkrj.co.jp/img/goods/img_connrod.jpg
connecting rod Aprillia GP-125.
Overall length 147.20 mm.
Width little end 15.00 mm.
Hole diameter the minor end 19 mm.
Width 15.00 mm thick end.
The crank pin 20 x 49 mm.
Bearing silvered 20x33x1 mm.
Hole diameter Big end 26 mm.
Connecting rod center hole interval 115 mm.
Little end bearing cage silver 15x19x19, 40 mm
Storändans stock basket silver plated with 15 pins, width 14.75 mm

MODEL
B-100P/B-120 W/W
OEM No. -11001
CODE No. BS0200B
B.E.BEARING DIA (mm)：Ａ 26.00
S.E.BEARING DIA (mm)：Ｂ 18.00
B.E.& S.E. PITCH (mm)：Ｃ 110.00
B.E.THICKNESS (mm)：Ｄ 17.00
S.E.THICKNESS （mm)：Ｅ 17.00
CRANK PIN DIA (mm)：Ｆ 20.00
CRANK PIN LENGTH (mm)：Ｇ 20.0 X 49.0
STROKE 2
CON,ROD CODE No. CS0240X

MODEL
GT-250A/M W/W
OEM No. -11001
CODE No. BS0400B
B.E.BEARING DIA (mm)：Ａ 26.00
S.E.BEARING DIA (mm)：Ｂ 18.00
B.E.& S.E. PITCH (mm)：Ｃ 110.00
B.E.THICKNESS (mm)：Ｄ 17.00
S.E.THICKNESS （mm)：Ｅ 17.00
CRANK PIN DIA (mm)：Ｆ 20.00
CRANK PIN LENGTH (mm)：Ｇ 20.0 X 57.0
STROKE 2
CON,ROD CODE No. CS0240X

But yeah you can say I told you so if.
Only If it is ever completed and ever snaps a rod.:shit:

[F5 Dave]

Probably still in there, but he hasn't raced for some years. Used to be the fastest 100 about.

A snapped rod cuts the cases in half leaving nothing salvageable bar the gearbox & puts you on the ground quicker than you can think.

[husaberg]

Probably still in there, but he hasn't raced for some years. Used to be the fastest 100 about.

A snapped rod cuts the cases in half leaving nothing salvageable bar the gearbox & puts you on the ground quicker than you can think.


My father snapped a rod at Southbridge while i watched. the Rod snapped in 1992 ish and he still limps.
The engine is still on the bench as a reminder, the crankcases and crankshaft are unscathed the barrel and piston head are not so nice.
A virtual choc fish i anyone can figure out what model of bike it was?
Hint 250 single four stroke eccentric adjustable tappets, aluminum alloy Rod, shell bearing big end.
Grumph is excluded. As he will know straight away.