ESE's works engine tuner

[Frits Overmars]

it seems that Jan realized just from the Beginning that the rotary inlet is the best for power. there are not many pictures showing Jan with piston port or reed valve engine. maybe a stupid question but is that the only reason (power) that he so to speak started straight off with the rotary inlet system or are there other reasons that makes him prefering it?Jan should be answering this really, but I'll give it a try. I assume he started with a rotary because everybody in GPs was using that when Jan built his first engine.
For his own constructions he always stuck to rotaries, with one exception: the reed valve Rumi. It produced 46 hp on the test bench in a season where the world title was won with 42 hp, so our prospects were bright. Sadly this could not be said of management...
Jan made a direct comparison at Derbi where he developed the RSA while Lorenzo's GP-winning reed valve Derbi was still around. Jan worked on both engines, extracting 49 hp from the reed valver before dropping it in favour of the rotary RSA that produced 10% more power with the same cylinder.
The rotary engine has other advantages over the reed valver: setting the carburation is much less fussy. But the power difference is the main attraction.

[seattle smitty]

[QUOTE=Frits Overmars] As long as 30 years ago (yes, I'm an old sod) you would not find any form of radiator on Jan Thiel's Garelli test bench. There was a hose from the cold water tap to the engine and a hose from the engine to the sewer. And Jan was not afraid to measure a stone cold engine at full throttle. It made him realize were the power is, and how important cooling is. (QUOTE]

Frits, one reason I keep asking, even after someone who knows more than I do makes an assertion that to his mind is clear and final, is that if we can get him to keep amplifying his experience we might see the WHY of his conclusions. And right or wrong, we might then decide it doesn't quite apply to our individual situations.

For instance, if I just decide, "Well, okay, the man says 'the colder the better.'" I could ram-feed LOTS of water into an outboard at higher pressure than city-water faucets, using huge hoses and manifolding to put it into the engine at numerous locations and with lots of drains at the other end, and I could build a head that has internal fins giving ENORMOUS surface area for this river of water to flow over. Going on, you tell us Jan "was not afraid to measure a stone-cold engine at full throttle." What is a duffer like me supposed to make of that one if I don't ask about it, seeing that many other two-stroke owners have skidded pistons that weren't yet expanded and sealing well (commonly seen as a "four-point seizure")?? Which of these incompatible "findings" applies best to MY engine? Should I massively cool my engine and start buying boxes of semi-finished pistons that I can turn with a lot less taper and clearance than standard? This kind of thing is why I hope to learn what's behind anybody's flat assertion of what is best practice.

There is not a pfennig of prize money in the racing 98% of us know; a boat is a hole in the water into which you pour money (there must be a similar saying for bikers and karters), so we have to be a little cautious. So as another "for instance," when Wobbly says cool the squishband, and you say, no, squish harder, I'm inclined toward cooling it because I can't be whacking too many pistons trying to find the sweet-spot, a dimension which will exactly apply only to THAT engine. As an eighth-grade teacher once told me, "Sometimes discretion is the better part of valor."

(EDIT) You're old, okay, . . . but an "old SOD"??? Frits, that's MORE than I need to know!!

[Frits Overmars]

Frits, one reason I keep asking, even after someone who knows more than I do makes an assertion that to his mind is clear and final, is that if we can get him to keep amplifying his experience we might see the WHY of his conclusions. And right or wrong, we might then decide it doesn't quite apply to our individual situations.You know the type of kid who drives his parents crazy because he keeps asking 'Why?'
No, I'm not going to say what you fear right now. I'll just say that I was that kind of kid myself, and still am, so I can understand what you mean.


Which of these incompatible "findings" applies best to MY engine?That works two-way only: I can only answer your questions if I know your engine inside-out. But that would be a day job, and I've already got one.


Wobbly says cool the squishband, and you say, no, squish harder!I never said no to cooling the squish band. And I said 'squish hard', not 'harder' because I do not know how hard he is squishing right now.

[Muciek]

Finished Webco reproduction heads for RD350/400 with Wobbly designed combustion chambers :niceone:

309101309102309103309104

[wobbly]

There is a 250 version as well, jfyi,and luckily for me the first back to back dyno run gave +6Hp.

[seattle smitty]

I can only answer your questions if I know your engine inside-out. But that would be a day job, and I've already got one.

NO, no, I posed the question rhetorically, exactly to point out that to make my own decisions for my own machinery, I want to get some sort of understanding of what went into your decisions . . . . much as I might want you to retire, move to Seattle, and become my personal private outboard engine-builder.

But I WOULD like to know why Jan Thiel could go WFO with an un-warmed-up engine, where our engines, given that treatment, will likely go RRRRIIIIIINNNNNGGGG-bleeeeeugh-squeak . . . AND whether when you/he found that very-well-cooled engines worked better, did you alter the taper and fit-up of your pistons??

[F5 Dave]

So the reduction of squish.

All figures made up and assuming a road based crank which may not be as stiff,

lets say a static squish of 0.7mm

start the engine & it becomes 0.3
9000 it goes 0.2
12000 0.1

does that sound reasonable order of magnitude?

So you will have more mixture trapped at 9000 than 12000.


It can be a tricky phenomena. Just Sunday I was getting flashes on my Knockgauge at the end of the straight, yet up the hill in 6th right through to over-revving it was fine. You'd think that would put more load on.

[Yow Ling]

But I WOULD like to know why Jan Thiel could go WFO with an un-warmed-up engine, where our engines, given that treatment, will likely go RRRRIIIIIINNNNNGGGG-bleeeeeugh-squeak . . . AND whether when you/he found that very-well-cooled engines worked better, did you alter the taper and fit-up of your pistons??

Possibly because the piston and the bore had similar expansion rates as they warmed up, unlike a CI sleeve which will expand much slower than the piston heats up

[wobbly]

The Aprilia setup with 0.7 squish I believe would just clip at the absolute overev margin of 14500
Now I have the squish cooling organised in KZ2 I can run down at 0.9 ( from 1.3 min ) and it just clips at 15200.
The 66 bore Banshee/RZ based race engine with 58 stroke set at 1mm will clip at 12200.
A TM125 MX engine for open karts would clip at 13200 with 0.6mm
A CR250 road racer set at 0.9 will clip at 11400.
That gives you some idea of the state of play from real experience.

The big open class Jetski World Champ engines I used to build needed an absolute minimum of .15mm = 0.006" clearance
on 78 to 92 bore when running 40*C out of the case and 60*C out of the head.
On the dyno the power would fade at the end of a 30 second pull if the case went over 40* - much under that and we would certainly squeek a piston.
We used restrictor jets on the individual 6 outlet points to regulate the local temps.

[Frits Overmars]

I WOULD like to know why Jan Thiel could go WFO with an un-warmed-up engine, where our engines, given that treatment, will likely go RRRRIIIIIINNNNNGGGG-bleeeeeugh-squeak . . . AND whether when you/he found that very-well-cooled engines worked better, did you alter the taper and fit-up of your pistons??
Possibly because the piston and the bore had similar expansion rates as they warmed up, unlike a CI sleeve which will expand much slower than the piston heats upRight, and it's self-amplifying too: the piston will heat up much faster in a sleeve because the sleeve itself won't conduct sufficient heat to the cylinder body.
I don't hate sleeves without a reason.
Of course the piston shape (an oval, conical barrel) was adjusted on the basis of the wear pattern. But that's nothing new; you've got to do that with every engine.

[F5 Dave]

The Aprilia setup with 0.7 squish I believe would just clip at the absolute overev margin of 14500
Now I have the squish cooling organised in KZ2 I can run down at 0.9 ( from 1.3 min ) and it just clips at 15200.
The 66 bore Banshee/RZ based race engine with 58 stroke set at 1mm will clip at 12200.
A TM125 MX engine for open karts would clip at 13200 with 0.6mm
A CR250 road racer set at 0.9 will clip at 11400.
That gives you some idea of the state of play from real experience.

.. .
Thanks. What it doesn't tell me, if I really needed to know other than idle curiosity, is what the dynamic squish is at lowest usable revs. The numbers seem to indicate that heavy pistons and lots of revs continue to stretch but I'd imagine that bearing clearance would take up early on. In absence of measuring equipment one would need to build an engine with say 0.5 and rev it to a low figure and check. Just curious.

[kel]

Question for Wobbly, do you know the name of the tape, and where I might purchase this tape, as used for masking the squish area of piston pre ceramic coating (the stuff that was used by BSL before sending pistons to HPC). Thanks

[wobbly]

As far as I know HPC made a circular mask that simply sat on the piston crown, and the ceramic was sprayed on like a paint.
Then it was heat cured.
Because there was a definitive line around the squish edge where the piston became flat, it was easy to align the mask.

[husaberg]

Thanks. What it doesn't tell me, if I really needed to know other than idle curiosity, is what the dynamic squish is at lowest usable revs. The numbers seem to indicate that heavy pistons and lots of revs continue to stretch but I'd imagine that bearing clearance would take up early on. In absence of measuring equipment one would need to build an engine with say 0.5 and rev it to a low figure and check. Just curious.

I seen something with a v8 block ran headless and filmed slow mo, The rod stretched a lot. I have pulled that figure out of my ass.
Anyway force equals mass x accerleration.

But here is the F1 stuff

Cosworth's 2005 V10 was the TJ model, which had its max RPM at 19,000 rpm. With next year model CA, Cosworth took the uncompromising approach of targeting 20,000 rpm from the outset. This was the first time it had produced such a high-speed V8. At 20,000 rpm the CA's maximum piston acceleration was 10,616 g while the load imparted on each crankpin by the associated piston and con rod reached a very substantial 5937 kg at that unprecedented speed. To put that into context, an anti-ballistic missile attains a g-force of only 100 g while 5937 kg is approximately two and a half times the weight of a Rolls Royce Wraith! Cosworth, to counteract high friction that can counteract horsepower gain, applyed a Diamond-Like Carbon (DLC) coating to the piston skirts.

Revving to 18,000 RPM, a modern Formula One engine will consume a phenomenal 450 liters of air every second, with race fuel consumption typically around the 65 l/100 Km. Revving at such massive speeds equates to an accelerative force on the pistons of nearly 9000 times gravity (9000 G).


Of course, the biggest challenge has been holding everything together as reciprocating and rotating parts are worked ever faster, and generate increasingly fierce loadings. Even at "only" 12,000rpm there are seven tons of load going up a con rod, which responds by growing longer, then 12 tons going down it, which unavoidably shortens it somewhat! F1 piston travels only about 40 millimeters and acceleration from 0 to 100kmh has been measured at 0.0005 seconds. The bore is roughly 98 millimeters (called supersquare bore (wider than higher)).
The engines produce over 100,000 BTU per minute (1,750 kW) of heat that
must be dumped, usually to the atmosphere via radiators and the exhaust, which can reach temperatures over 1,000 degrees Celsius. Nonetheless a Formula One engine is over 20% more efficient at turning fuel into power than even the most economical small car. Unsurprisingly, engine-related failures remain one of the most common causes of retirements in races. The engine oil capacity is about 3 litre or so. This is because of the dry sump system.

Calculating inertia force
http://www.wallaceracing.com/Calculate-Inertia-Force-of-Piston.php

[rodg]

Long time listener (lurker?) first time caller....

Thanks to the lads at the house of speed I finally got my AM6 (50mm malossi mhr replica barrel) powered TZ 80 onto the dyno tonight. Unlike pretty much everyone else on this thread I'm a strict amateur when it comes to building motors and my first up dyno run confirms such! I was pretty confident I had built up a tidy little motor that would deliver 15+ HP pre-tuning (it feels faster than my 14-ish HP FXR).

First dyno chart below (red) came as a bit of a shock - 10HP!. A bit of fiddling with the ignition (PVL Go Kart analog) and leaning up the main pushed us out to 15HP pretty easily but as you can see the graph is horrid.

Thanks to the generosity and experience of the lads we'll spend a couple more nights on it and i'll keep you posted.....

[adegnes]

Maybe start accounting for rod compression when aligning the piston and transfer port floors @btdc, just like you account for stretch when setting the squish?
I've actually done just that, piston dome is 0.3mm above transfer port floors, I don't know exactly how much rod compression there is, just picked a number. (39.1x40 stroke/bore)

[chrisc]

Thanks to the generosity and experience of the lads we'll spend a couple more nights on it and i'll keep you posted.....

Ah Jesus, why would they do such a thing, you're fast enough on that thing already!

[F5 Dave]

Maybe start accounting for rod compression when aligning the piston and transfer port floors @btdc, just like you account for stretch when setting the squish?
I've actually done just that, piston dome is 0.3mm above transfer port floors, I don't know exactly how much rod compression there is, just picked a number. (39.1x40 stroke/bore)
Hadn't even Thought of that but it makes sense,. . . though empirically the slight overhang might be worth it for a teensy longer flow cooling that piston.

[Frits Overmars]

What it doesn't tell me, is what the dynamic squish is at lowest usable revs.I can't for the life of me think of a reason why you would want to know that. What can you use this knowledge for? Please enlighten me.


In absence of measuring equipment one would need to build an engine with say 0.5 and rev it to a low figure and check.We have measuring equipment. You may remember the story where mechanical contact between piston and head fooled a detonation sensor into shouting 'deto!'
So minimize the chance of real detonation by retarding the ignition timing and run your engine until the deto sensor shouts. Because of this late ignition the pressure rise above the piston will be later than usual, so the force slowing the piston down will be less than usual. Then if you advance the ignition to its previous value, the touch-rpm that you just established will be safe at WOT. But close the throttle and the pressure will drop, increasing the piston overshoot.
This was the reason that the 100 cc direct-drive kart engines of yesteryear, that could be revved past 20.000 rpm, should be braked down to more civilized revs before you could close the throttle. If you did it the other way round, chances were that the con rod would self-destruct, taking the rest of the engine with it.

[F5 Dave]

OK that makes sense I think (slowly).

My thought process was that if you can help stave off deto by reducing squish to as little as possible, this is only most effective approaching peak revs. So at the bottom of the useable power there is more trapped mixture. But I wasn't sure how much more.

I also thought of the sliding head but it does seem complex for what might be minor gain. That said perhaps if you could decrease deto you might be able to crank up advance at 9000.

[wobbly]

The TZ80 dyno graph shows it has a very typical and very big tuning issue.
Sure it hit 15 Hp with jetting and ignition changes, but the power is then fading seriously with every gearchange - real bad, moreso for a water cooled.
This setting would eventually kill the thing on the track.
Any engine set up correctly will repeatably hold the peak power figure thru several WOT all gear runs, even better if its on a Dynojet 168 or similar with eddy current load control

[Frits Overmars]

My thought process was that if you can help stave off deto by reducing squish to as little as possible, this is only most effective approaching peak revs. So at the bottom of the useable power there is more trapped mixture.That makes sense Dave, I didn't think of that. But detonation at the bottom of the powerband is usually not a problem because the cylinder filling is not yet at a maximum then.
Perhaps if you could decrease deto you might be able to crank up advance at 9000.You certainly could, but that doesn't mean you would gain any power. It would be true for foul-strokes, but two-strokes depend on exhaust gas energy and advancing the ignition reduces this energy.

[husaberg]

That makes sense Dave, I didn't think of that. .

Polini, did I think you posted a few pics of it ages ago......

[jonny quest]

You're talking about the variable compression ratio head. It didn't change squish, just chamber moved up and down

[Peter1962]

Polini, did I think you posted a few pics of it ages ago......

I think you are referring to this : http://2stroke.free.fr/culasse-polini.jpg

[husaberg]

I think you are referring to this : http://2stroke.free.fr/culasse-polini.jpg

You're talking about the variable compression ratio head. It didn't change squish, just chamber moved up and down
Yes Peter1962 .Oh I thought the squish band moved as well. but it obviously doesn't. Then again, it easily could with a few mods.........:scratch:

[jonny quest]

You don't want the squish to move to the clearances you're suggesting. Way to complicated a device for such precise movements

[wax]

The big open class Jetski World Champ engines I used to build needed an absolute minimum of .15mm = 0.006" clearance
on 78 to 92 bore when running 40*C out of the case and 60*C out of the head.
On the dyno the power would fade at the end of a 30 second pull if the case went over 40* - much under that and we would certainly squeek a piston.
We used restrictor jets on the individual 6 outlet points to regulate the local temps.
Wobbly did you make an error and put the decimil place in the wrong spot there
is this supposed to read 1.5 mm

Was this a 951 seadoo with a huge piston

[wobbly]

Nope - 6 thou is the correct number and yes a 951 out to near 1200.

[wax]

wow thats tight squish.
Am i reading it wrong is that measured at a certain rpm or a static measurement
Yeah I have been around the big bore 951 a little as well not at the same level as you i never took one to the world titles
They make good power until they dont and then you throw it all in the bin

[Grumph]

wow thats tight squish.
Am i reading it wrong is that measured at a certain rpm or a static measurement
Yeah I have been around the big bore 951 a little as well not at the same level as you i never took one to the world titles
They make good power until they dont and then you throw it all in the bin

i think he's talking piston to bore....

If it is Wob, and they were forged pistons, did you have a shrinkage problem ? Or set them up tightish and run through several heat cycles ?

[wobbly]

Yes, i was referring to bore clearance needed when using the cold water from the tap - or Lake Havasu in this case.
Smitty was talking about the loose clearances they have to run when going WOT with cold water in boat racing.
The only issue was simply that the low inlet temp along with an iron sleeve meant the piston would always be growing far faster than the bore size.
In the smaller bores there were cast pistons available and after long run in cycles these would survive at 0.004".
But the big bores were forged by Mahle, and nothing I did regarding slow run in, and sanding off the high spots etc would stop them locking up
if under 0.006".
Of course this let the piston rock all over the shop, and the rings had a real hard time sealing effectively for long, but was the only way to get over 220 Hp
from the big twin for open class racing against 1200 triples that had more power but were way heavier than the SeaDoo with titanium/magnesium everything, and a carbon hull.

[wax]

OK my bad, i read it wrong. I was questioning it in my head thinking he cant be serious

[Drew]

Hang on, if the insert moves inside the head does it not fail to dissipate heat properly?

I thought everyone was saying tight as fuck is the only way to mate parts, or things would overheat very locally and the shit would hit the fan.

[wax]

Wobbly have you ever played with a triple engine with one expansion chamber.
ie as in an out board style or triple jetski engine.
Thats the one using 120 degree pulse tuning. I looking at designing another chamber for my ski to move it in a different place but i am not convinced any of the software out there will cater for what I am doing.
Its going in a stand up ski and there is not the room for triple pipes

[F5 Dave]

I was thinking of an insert sealed at the sides but with a rubber as a spring at the top for 0.3mm movement of the squish. But there's a problem.
either way hardly seems worth it when you could spend your time on pipes. Like I desperately should do.

[Drew]

I was thinking of an insert sealed at the sides but with a rubber as a spring at the top for 0.3mm movement of the squish. But there's a problem.
either way hardly seems worth it when you could spend your time on pipes. Like I desperately should do.

Make me a couple for the GT too would ya.

[TZ350]

1120 already !!!!!!

Crankshaft Balancing:- http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1121
and at the bottom of this page too http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1120



Question for Wobbly, do you know the name of the tape, and where I might purchase this tape, as used for masking the squish area of piston pre ceramic coating (the stuff that was used by BSL before sending pistons to HPC). Thanks
As far as I know HPC made a circular mask that simply sat on the piston crown, and the ceramic was sprayed on like a paint. Then it was heat cured. Because there was a definitive line around the squish edge where the piston became flat, it was easy to align the mask.

Turns out that it is a heavy vinyl that sign writers use. You could get vinyl rings cut at any good signwriters. The areas of the piston crown that is to be ceramic coated gets grit blasted and the vinyl rings are used to protect the squish area from the grit blasting and spray application of the wet ceramic.



Wobbly, I'm a little confused. You are critical of Iridium plugs, and advocate the use of the R7376.

Now I see, in the NGK plug specification chart at http://www.ngksparkplugs.com/docs/RacingSpecs2013.pdf
that R7376 has an Iridium centre electrode.

When you criticised the Iridium plugs, were you talking about the sales name of that range, rather than the electrode metal?
Plain old Iridium plugs are a brand name, and yes they have Iridium fine wire centre electrodes. As I said, these will drop the ceramic at the slightest provocation.
The R7376 has the Iridium centre, but also has a Platinum earth fine wire strap. The construction is completely different, and is dead reliable.


The only thing that will make a plug ceramic crack and fall off is deto. In an ordinary Iridium even a few light deto pings will make it happen instantly.

A whole large batch of B9 or 10 EGV plugs the ceramic fell off for no reason, and NGK have acknowledged this in writing but I bet the importer will deny all culpability ( lawyer word for the day ).

But none of this dumb shit would ever happen if you would listen to me and use a RACING plug in a RACING engine - B7376 has never once lost a ceramic or a fine wire laser welded earth strap due to any tuning issue.

This is why they cost a bit more, still,its less of a piss off than loosing a race, and way less than the cost of a new piston etc.


Well I do like the chamfer/flat top on the piston edge ( ha hah,I showed Harold that idea when I designed the BSL500, and it ended up in the Swiss Auto,Pulse, as well ) but it also appears to have a radius,that now, we have VHM using to make better power from KZ2 engines.

But if Harold copied a certain Honda cylinder, then it for sure wasn't a late model A Kit as they ALL had very a oval Exhaust exit shape at the cylinder face that transitioned into a round within the flange to mate with the header - no step = alot more power.

Honda even issued a tech bulletin that said you would loose alot of power if you ground the cylinder round to match the
very old design spigot on the 125 customer bikes.

The best power I have ever got from a T port 125 cylinder was with a 41 wide by 32 high oval, and that was tested back to back starting at 40 round and progressively inserted/ welded and ground smaller and smaller in the cylinder and spigot.

The final design with the 41 by 32 dimensions used as cast in the cylinder - and CNC machined in the spigot made another Hp over my welded test pieces.

But shit Harold, every dumb arse could see that shaping the tang below the boost port was worth some power, allowing better flow from the reed cavity into the case area.


Hello. What you mean by "chamfer/flat top on the piston edge"? This kind of piston top: http://www.mitaka.co.uk/YAMAHA%20PISTONS/PT.05YZ125.htm ???

I have seen somewhere that the chamfer on a flat piston improves power before peak? But the head must have this shape also for the result to happen. So, with this kind of flat top on the right head shape we will have more power everywhere compared to a domed top on a Honda Cylinder?!




The Lectron 40HV flows alot more air than a 38mm SPJ but has a venturi behind the slide of 36mm.
Thus at part throttle it acts like the smaller carb.
Insanely easy to jet.
Just get a pair of 5-2 and 4-2 needles, then fine tune the high range with 40 to 70 powerjets - also makes equalising & fine tuning each side simple as well.
The TZ400 when it ran at PI had 4-2 with 85/90 on top, so I will now go to 5-2 and drop down to around 50 powerjets.
And when you want to go sex plus I have made some inline solenoid bodies that will switch the PJs from Ignitech.


Cheers. So what is the off throttle fuel feed like? I sort of like having the rich pilot when the brakes are on into a corner.


Rich wants simple - APTs need alot of dicking around to get even close as they dont have a big matrix of needles with top end and mid
taper changes.Makes tuning a twin more than twice as hard.
Plus no fine tune powerjet.
The trick venturi shape is more suited to great throttle response for say buckets on a kart track, or MX.
They have apparently recently done some more needle combinations, but I havnt had time yet to look into this.

Re the Lectrons bottom end tuning on the overun Rich,simply turning the rod in 1/4 turn increments makes for super easy changes in off idle fuelling.
And as I said about the TZ400, it had 4-2 needles with big powerjets, so simple next step is a 5-2 with smaller PJs - will end up with same egt and better part throttle corner response.
No effect on the bottom or mid tuning, just rearranging the top end.
The 300 motors will end up making some more power than the old TZ based 400s - 86RWHp so that motor is a bit overcarbed, but the HV venturi helps the mid response a heap.
One of the 300 customers wants some 38PJs so maybe you can do the Lectron thing for no outlay.




... reminds me of the man who went to a fortune-teller to get some palm-reading done. The palmist promised him he would meet a gorgeous woman and get married. The man replied: "Some palmist you are. I got married to her allright. And divorced too!"
The palmist said: "What do you expect from me when you never wash your hands."
It's the same with spark plug and piston reading.

This >> https://www.facebook.com/Techgp/photos_stream?tab=photos_albums :Punk:


http://tyga-performance.com/site/index.php?cPath=73_191 and I see prox do a kr150 piston.

Bucket Racing at Edgecom http://www.kiwibiker.co.nz/forums/showthread.php/150352-Team-GPR?p=1130838589#top

Interesting workshop projects:- http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page46


dimensions for a Honda RS125.

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301482&d=1411381933



Carb manifolds
http://www.jetsrus.com/mounting_flanges/mounting_flanges.html
http://www.allensperformance.co.uk/products-manifolds.html





309622

A loncin after market CDI stator converted to a 12V DC generator for the Ignitec

http://www.aliexpress.com/item/Performance-Racing-Magneto-Stator-Rotor-Kit-Dirt-Bike-LF-for-Lifan-140-150cc-CDI/1731580291.html

Watch out for these, my one failed, that was my issue at Taumaranui, the rotor was moving in relation to the taper.
The taper wasn't slipping, nor were the rivets but it broke between the taper and the part that rivets to the rotor in such a way that it appeared normal until under heavy load, then it would move.


I am posting far to much and doing far to little but I found these as the CR125 ones will get harder to find.
Ktm125-300 seem to have a nice small rotor stator Kokistan with 25 watts or 50 watts aftermarket
http://www.cafehusky.com/threads/08-cr125-with-ktm-125-lighting-stator-howd-ya-do-that.2755/
309628309629309630

http://www.thumpertalk.com/topic/930729-ktm-200-flywheels/
http://www.rmstator.com/en_ww/products/rm01374-high-output-stator-ktm-1998-2011-exc-mxc-sx-sxs-xc-xc-w?___from_store=en_ww
http://www.ebay.com/itm/NEW-KTM-125-EXC-MXC-SX-SXS-50W-LIGHTING-STATOR-MAGNETO-SOURCE-COIL-/221120717793
pretty sure it might be very similar to the Honda cr one
Plus I also found these.

Its an outer rotor from HPI
http://www.hpi.be/210.php
http://www.hpi.be/item.php?item=210K008
https://www.treatland.tv/PUCH-HPI-CDI-mini-rotor-ignition-system-24K-gold-p/puch-hpi-cdi-90-gold-used-2.htm
309625309627309626


You cant use the old CDI cheater trick with a PVL.
It uses the same coil to charge the capacitor on the N pole magnet ,then triggers the output circuit with the S pole using that same coil.
In the usual systems of old there was a charge coil, and a separate trigger .
If you simply put a small value capacitor across the trigger this would completely change its inductive reactance curve.
In old TZ350s we could set the static at say 4mm, and the cheater trigger mod would pull it back to 1.5mm at 10,000.
The same idea can be used to cheat the ignition timing in some kart classes but I know nothing about any of that.


Thanks for your explanation Wob.

309598

At first I had trouble getting my head around their graphs, they did not make sense until I realized that the "0" line represents the static timing point which could be any number of degrees one chooses BTDC and their curve moves + and - relative to that point.

309597
As I now understand it, in this graph, if the initial timing was set at 15 deg BTDC then "0" on the graph means 15 deg BTDC and at 2000 rpm the real ignition point is 15 + 3 = 18 deg BTDC, at 8,750 rpm it is 15 + 0 = 15 deg BTDC and at 12,000 rpm it means 15 - 3.5 = 11.5 deg BTDC.

Also things can get confused when using a timing light because the trigger circuit in the timing light has some capacitance and therefor some delay in flashing the light after the triggering event. This has the effect of the timing appearing to be more retarded than it really is. At low rpm when there is plenty of time this error is very small and not much of a problem but at 9 - 10,000 it can get very noticeable and at 12 -14,000 significant.

Exaggerated retard due to the timing light flashing late, is just another thing to watch out for.


Adding a 0.47mfd/200V cap across the trigger will create around 1*/1000 rpm retard.
So with around 6mm static I think it stared at 35* and by 10,000 it had 1.6mm = about 17*from memory
Thus the old pretty much straight line became a crude retarding unit, with extra mid advance for drive, and extra retard over the pipe for overev.


http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=249252&d=1319412316
He used to do a roaring trade in them
last paragraph first page below. keep clicking on it till it is large enough to read
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=249261&d=1319423423
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=249262&d=1319423495

I can't remember what the variable capacitors are called but they used to be in radios.....
309650


555's are useful little beasts........But to map them would take a set up like wobs...
Post it again Wob

oh I found it once I figured out how to spell vacuum





309651

https://www.youtube.com/watch?v=pA6kjjEMiaw


I used NGK R7376-10 racing plugs ( I use them in everything ) as these are same plug as is sold in the shorty version for
GP bikes with special cap for silly money.
But these plugs are normal body size,and have the Iridium electrode and Platinum small ground wire for around 40usd.
The NGK racing plugs have special resistors in them.
The 5K plug with no cap resistance and Magnecor 10mm wire works a treat with no RF problems for the Ignitech.

I use Ditex ignition test gear into my laptop.
Here is a video of the twinfire with Crane PS92N enormous cdi coil, on my test rig with CR125 stator/rotor/reg/cap.

http://www.youtube.com/watch?v=pA6kjjEMiaw&feature=plcp


Its a vacuum cleaner motor with a light dimmer rheostat and reverse switch for speed and direction.
Small toothed belt drive so I can use a big degree wheel on one end of the shaft and the ignition on the other to check timing curves..
Shaft slides in and out on eccentric lock bearings to position the rotor correctly.
I have seen nicer rigs using spindle moulder motors, but the old Hoover motors are free.


Here is a pic of cranks for Aprilia 250.
Full circle, full width, plenty of Mallory, high inertia, very low in cycle speed variation, lots of power and overev - why isnt your crank like this??

Also pic of my Ignition rig.
A vacuum cleaner motor with light rheostat, also reversable, has protractor on the other end.
I use a cheap kart rev counter and a strobe.
Doing curves on anything is easy, once its set up.


309599309600
A couple of pictures for you all

Look carefully at these photos and you will see that the exhaust port floor is higher than BDC.



12v water pump epic output
https://www.12volt.com.au/
Circulation Pumps

Jabsco Cyclone Circulation Pump

Robust, high flow, quiet running, long life pumps for hot water and heating systems and other circulation applications. This heavy duty centrifugal pump has a stainless steel head and and open, no-clog impeller design to easily handle small debris and high temperatures.

Suitable for fresh or salt water, bilge water and mild chemicals.

Not self priming - install below the liquid source.

3 year limited warranty.
•29 GPM - 110 litres per minute flow

•Long life mechanical seal

•Centrifugal design moves liquids quickly and efficiently

•3/4" female BSP female threaded ports

•12 volt 8 amp Cyclone pump

•24 volt 4 amp Cyclone pump
Jabsco Cyclone Circulation Pump
PUJCY12V Cyclone 12v $539.00
https://www.12volt.com.au/General%20Htmls/webcat2003/pumps%20pics/jabsco_cyclone.jpg

12VDC 8A Dimmer / Motor Speed Controller

DC speed controllers are ideal for slowing down pumps and motors or dimming lights but commonly use resistance circuits and are very inefficient.

The pulse width modulation (PWM) used in this controller allows you to vary the output from 0 to 100% while maintaining a very high efficiency.

When used on motors this ensures full torque is available at very low speed and the motor won't shudder at start-up.

Operates on any 12VDC system and capable of controlling devices rated at up to 8 amps.

The internal circuitry is fully potted and the control potentiometer is splash proof making this suitable for marine environments and other harsh conditions.


Dimmer / Motor Speed Controller
MP3209 8A 12VDC dimmer $39.99

[wobbly]

Yep, the concept of the system used by Team Roberts was admirable, but as Dave points out the dynamic squish in reality varies with rpm and I will add, bmep.
Making the head retract as the cylinder pressure increases against a set pressure above the insert is clever, but as is the usual case, no free lunch.
Squish clearance needs to vary with rpm ( and by default bmep ), so having the chamber fixed in space to the cover, and the squishband area moving independently
seems a really great lateral thought process that ticks all the boxes.
Minimising the end gas volume at all rpm, via a variable squish height, but having a fixed chamber would then give high com and high squish at low rpm ( bmep )
then translating into slightly lower com, along with low squish volume at high rpm ( bmep ).
Dropping the com as the engine comes onto the pipe, maximises the energy distribution as we know is actually needed, but at all times the squish volume is minimised - brilliant.
Having the close tolerances needed along with O ring seals wont affect the temp gradient we want ie a cold squish area, and a warmer chamber, if the thought process of the really effective squish cooling
scenario I have alluded to is used as well.
Hey, hey, maybe a small step for Dave, a giant step for 2T technology, good shit.

[F5 Dave]

Great, now make me a pipe and you can keep the patent.:msn-wink:

[wobbly]

Yea right, the variable squish concept took 2 moments of intellectual input - doing your pipe will take 2 days of sim and then CAD.
I will post you my account details.

[F5 Dave]

And when I only had to support myself that would have been a good idea.

[seattle smitty]

Very interesting discussion here, which I'm trying to wrap my remaining neurons around . . .

In talking about squish clearance, you're talking about accommodating the stack-up static tolerances of all the moving parts involved, plus the "growth" of the assembly with rpm; the neat rotating and reciprocating we see when turning the assembly over by hand, becomes a mad wriggling and flexing and loading/unloading in every axis, if we could see it in stop-motion with a stroboscope. You can't (anyway I can't) plug basic engine dims into a formula for determining squish clearance . . . b/s, rod length, weights, rpm, compression, there'd be no end to it, and how would you account for all the different ways various manufacturers build the crankshafts and how they support them with bearings and how much their cases might flex, OR know the rpm bands you have to pass through at which there are harmonic convergences that amplify the shakes and flexing even more! With the complexity and innumerable variables here, I don't see how anybody could write a program that would reliably tell you ahead of time that at 8500 you'd need X amount of squish clearance, while at 9500 you'd need X plus .0012", at 10,500 you'd need . . . and so forth. You couldn't plug in other numbers, an increase in rod length, or a heavier flywheel, or a lighter piston, and have the program re-plot your squish-clearance needs throughout the powerband.

But, if I try to list all of the parts, all the clearances, and all of the effects, as if I were going to write such a program, I can start seeing places where I might make some change, the goal being to reduce the highest amount of squish-clearance, the clearance I have had to build into the engine. Do I have room to replace a single-row with a double-row bearing at one end of the crank (and still have room for a seal?)? That's an actual example of a thing I was able to do on a very old 250cc Konig, and required adding material to the crankcase before I could bore it out for the longer bearing-plus-seal. Can I lighten a piston or a wristpin? I know that miniscule reductions in weight become big numbers at racing rpms. Aannnd so forth.

But the part of this I wonder most about is the design of and balancing of crankshafts. Car racers send their stuff off to a balancing specialist without a second thought. Maybe you guys do too, but in my out-of-date experience, 2-stroke racers, or at least outboard racers, mostly just use the parts as they came from the manufacturer. Maybe some of them will match-balance their pistons, and a set of rods end-for-end, which you can do with a gram-scale and homemade fixture to hold the rods. But as to assembling and truing a crank and sending it off to be balanced, I think everybody I knew didn't want the hassle of pressing it apart again, installing rods/bearings, and re-truing (never much fun), and most of us knew little or nothing about "balance factors" and Mallory-metal and other higher-order balancing considerations. We just figured it was "close enough." Well?? Is it?? Are you going to tell me (I hope) that you Kiwi bikers are miles ahead of us in this realm of technology, and you know all about it and build it into your engines?

For instance, take a 125cc single. What we hear is that you can't balance a single, it's going to shake and the best you can do is the move the imbalance around to where the shaking engine isn't hammering the frame mounts, the rider's hands, or the engine's own components. But you can look at different motors and see differently sized and shaped and balanced cranks. Presumably, as with all other aspects of engines, some of the manufacturers have done it better, some not so well. How does an owner, especialy a racer who does his own wrenching and modifying, look at it and know? Maybe if he carved some metal off the corners of the crank, or had a slug of Mallory metal added to the crankshaft or a flywheel, he could reduce some of the high-rpm shakes and thus need less squish clearance. If by doing this you could reduce the amount of squish clearance you have to add in going from 8500 to 12,500, you'd have at least reduced the problem that has been under discussion for the last few pages.

Has anyone written about balancing 2-strokes? Not the usual quickie but at length, and in language accessible to amateur racers who are not engineers?

Counter-balance shafts would be part of the extended subject. A few engines, singles, have them, but more of us might want them, since they reportedly don't take a significant amount of power to operate. Guys here can build anything; how can we figure out how to design ourselves a counter-balance shaft? For a single? For an opposed-twin, for a parallel twin, for an inline triple (notable shakers, sometimes)?? Guys here are adding rotary valve valves and drives to their reed-fed engines, and a disc rotary valve is unbalanced, and must add a bunch of shake when spun up into five figures. How do we counter-balance that shake? Depending on the plane of the rotary valve, it very well might add to the squish clearance needed, especially in one of those transitory harmonic convergences.

Certainly the first reaction including mine, is "Oh balls, this is way over-thinking, it's close enough, the real answer is another beer!!" But if we thought this way all the time, this thread of TeeZee's would not exist . . . .

And then Dave wouldn't have come up with his floating squishband idea . . . pretty cool, Dave, but what I would hope to do with the suggested re-balancing and counter-balancing is reduce the distance your gizmo would have to float.

[F5 Dave]

All I came up with was the conclusion I needed to spend more time on the basics:msn-wink:

Try your luck with the search feature, balancing has been covered before, but 1100 pages needs a computer and TZ's page summaries.

[wobbly]

You dont need a pile of code to do engine balance.
Its been established for a long time that a factor of 55 to 58% where the cylinder is reasonably close to vertical in a 2T is on the money.
Due to the huge masses involved with big dumb arse 4T things they overbalance to near 80% in something like a Norton Manx to stop the vertical
vibes of the handlebar/chassis assembly making the riders complain.
Its all to do with minimising vertical shake at the bars in a bike,but a similar action affects karts as well.
You dont need a balance shaft in a single 2T as plenty of them have been made with no issues of vibration at all.
In a parallel twin you need one if firing at 90* like Harolds KTM as this reduces the rocking couple cancellation action of a 180* firing.
But yes a balance shaft has been used in things like RS125s from Honda, and these are set up to cancel the unbalanced portion of the reciprocating mass.
Take the shaft out and rebalance with Mallory and are they faster - yes.
Add some more Mallory to create a higher inertia crank assembly without affecting the balance and are they faster - yes.
Just a bit more to think about.

[2T Institute]

http://www.ebay.com.au/itm/Woodland-Scenics-PINP3919-Pine-Car-Derby-Weights-Tungsten-Center-of-Gravity-2-O-/281600524563?pt=LH_DefaultDomain_0&hash=item4190b30113

Here are some screw in tungstens 14g/ half oz each net add should be 11g

[speedpro]

Honda MB100s have a balance shaft. I have removed the balance shaft in one motor and rebalanced the crank. The balance shaft rotated in the opposite direction to the crank at the same speed. It assisted the crank counterweight in offsetting the forces in line with piston motion but opposed the counterweight effects at 90degrees to bore centreline. Obviously I had to increase the crank counterweight which I did by drilling a couple of holes in each web, one each side of the big end. It buzzes a bit at odd speeds and you have to be careful how the engine is mounted to reduce harmonics.

[husaberg]

Has anyone written about balancing 2-strokes? Not the usual quickie but at length, and in language accessible to amateur racers who are not engineers?

Counter-balance shafts would be part of the extended subject. A few engines, singles, have them, but more of us might want them, since they reportedly don't take a significant amount of power to operate. Guys here can build anything; how can we figure out how to design ourselves a counter-balance shaft? For a single? For an opposed-twin, for a parallel twin, for an inline triple (notable shakers, sometimes)?? Guys here are adding rotary valve valves and drives to their reed-fed engines, and a disc rotary valve is unbalanced, and must add a bunch of shake when spun up into five figures. How do we counter-balance that shake? Depending on the plane of the rotary valve, it very well might add to the squish clearance needed, especially in one of those transitory harmonic convergences.


Phil Irving tuning for speed........
google has it
http://tuningforspeed.com/files/Tuning_for_Speed.pdf.



.

Measuring the balance factor of our Suzuki GP125,s

The round bar is very nearly as good as knife edges.

Pic-1 Finding the counter balance by hanging washers of a hook attached to the conrod.

Pic-2 Determining the mass "C" of the counter balance.

Pic-3 Determining the mass "R" of the reciprocating weight.

The balance factor B = C counter balance mass divided by R reciprocating mass.

The balance factor is.......B = C / R

As measured by me, it turns out that the balance factor of:-

A standard Suzuki GP125 is 69%

A Standard Suzuki GP100 is 76%

A GP with alloy plugs in the counter balance holes becomes 58% for the 100 and 52% for the 125.

When we recently dyno'ed two of our bikes with cranks that had the same 69% balance factors. The RS frame vibrated much more than the original GP frame did.

For us this supported the notion that there is no one correct balance factor, as the right balance factor is the one that works with the frame that the motor is mounted in.

I think it was SS90 that said that the balance factor that works best in a high output 2-stroke will tend towards 50% as the rev's go up. And we found that, that pretty much happened. When we put alloy plugs in the crank balance holes to raise the primary compression ratio. As an unintended consequence the balance factors changed and become less 58-52% and the engines became noticeably smother at higher rpm.

I asked Thomas about this and he said that motors with a wider spread of power and that are operated over a wider rev range like the std GP engine tended to have a higher balance factor than ones with a narrower power band like our hotted up engines. That made sense when you look at the Kawasaki 250 & 500 4-stroke MX bikes that have a BF of 60% and the big 4-Stroke cruisers & sport bikes at 70+ %.

It seems that the wider the rev range the motor is going to be operating over the higher the suitable balance factor will be. Its easy to relate this to the Kawasaki 4-stroke 250 Mx bike, same revs but wider power band, and a BF of 60%.

I have a Honda RS125 crank to look at next, I suspect it will be 50% but for different reasons.

Anyone can open a free account with Scribed where they can download "Tuning for Speed" by Phill Irving. http://www.scribd.com/doc/15392252/Tuning-for-Speed-P-E-Irving-1965-Tuning-Racing-Motorcycle-Engines

Phill Irving talks about CrankShaft Balancing and Balance Factors on pages 107 to 110 of the book which can be found on page 61 of the PDF.

The balance factor is C / R

.


I was able to weigh the RS crank the same way and the crank itself came out at 50%. The counter balance also looks to represent 50%.

I don't have all the RS here but after looking at the H100. The way I think it works on the RS is that the counterbalance spins twice as fast as the crank.

I said the counter balance "represents 50%" as I don’t think it weighs 50% but because it spins twice as fast as the crank its inertial mass becomes 50% as it spins around.

This allows the counter balance to work with the crank top and bottom to cancel out the piston and then it cancels out the counter weight of the crank mid stroke twice a revolution.

So it goes something like this.

Top:- Cranks 50% plus Balance Shafts 50% going down together cancels the Pistons 100% coming up.

Mid going down:- Cranks 50% cancels Balance Shafts 50% as they are now pulling in opposite directions.

Bottom:- Cranks 50% plus Balance Shafts 50% coming up together cancels the Pistons 100% going down.

Mid going up:- Cranks 50% cancels Balance Shafts 50% as they are now pulling in opposite directions again.

To do this the Balance Shaft has to rotate twice as fast as the crank.

So in theory you get a 100% balancing of the engine but really its just a bit of clever push and shove. As the crank is still 50% out of balance and when it pushes side ways the counter balance shoves it back and then twice a revolution the two of them gang up on the piston and pull it back.

It looks like the engine is balanced but there are really a lot of stresses going on inside.

I am not sure how you would go about matching the counter balance shaft to the crankshaft without making some comparitive weight measurements and doing some maths that takes account of changes in inertial mass with changes in rpm as it would not be a simple 50/50 weight thing for the whole rev range.

As the inertial mass of the counter balance shaft will change more than the crankshaft does with changes in rpm. So I guess you tune the weight of the counter balance shaft to work best in the rev range you want to use.

The balance factor of the RS crank is C/R = 50% of the reciprocating mass.

.


These Posts started 17th June on Page 70.

(2) Describe how to find the reciprocating weight.

Looking at the connecting rod it is easy to see that the Big End goes round and round and is all rotating mass. And the little end goes up and down and is all reciprocating mass.

But the bit in the middle is not completely either, it does a sort of wiggley motion. You can worry your self to death over it or just take a good old practical common sense approach.

Pic-1 shows the crankshaft divided into "Rotating Mass" on the left and "Reciprocating Mass (weight)" on the right.

Pic-2 shows the Reciprocating Mass (B) being weighed. When weighing its important that the conrod is level and only the little end touches the scales.

Pic-3 On these cranks its easy to see the counterbalance’s but in others you just have to imagine where they are as the can't be distinguished from the rotating mass.

The Rotating Mass within (A) naturally balances itself and is not involved in the crankshaft balancing process.

External items like Magneto Rotors, Generator Flywheels and in Cars Harmonic Ballancers/Flywheels/Clutches are fitted and ballanced after the crankshaft itself has been balanced. The crank is balanced first then the other round bits are fitted and balanced later.

In balancing the crankshaft there is only "Reciprocating Mass", "Counter Balance" and the "Balance Factor" which is the relationship between them.


Let:- "Counter Balance" = A "Reciprocating Mass" = B and "Balance Factor" = C

Then A = B X C .............now this is a real formula complete with a definition of terms.

This formula gives you the Mass (weight) of the Counter Balance if you know the Reciprocating Mass and the Balance Factor you want to use.

This is not new, Speedpro has allready posted hand drawn pictures like this, showing how he did it.
.


.

The KISS method of balancing a single cylinder 2 or 4-stroke.

Its all in the pictures:-

Pic-1 Find the total reciprocating Weight (Mass)
Pic-2 Find the Little Ends reciprocating Weight (Mass)
Pic-3 Find the Balance Facter (Ie. 65% is 0.65 X the ToTal Reciprocating Weight (Mass))
Pic-4 Leave the Little Ends reciprocating Weight (Mass) on the Scales
Pic-5 Attach the rest to the crank.
Pic-6 Balance the Crank.

From Phill Irving. page 109 "the wheels will roll freely along the straight-edges and show no tendency to settle in any one position; if not, the pin will go to the top or bottom according to whether the Counter Balance is to heavy or to light. Correction is usually made by drilling the rims."

Very simple, very effective, a very accurate way to balance a single cylinder crankshaft staticaly. If anyone can come up with a better static balancing method, Thomas and I would like to hear about it.

To find the existing balance factor of a crank shaft, you just more or less work through this process backwards.

.


The percentages quoted are "mass".

The forces generated by the reciprocating mass increases linearly as a function of the rate of reciprocating.

The force generated by the rotating mass increases as a square of the rate of rotating.

Therefore, even though at standstill the rotating mass only exerts a force equal to say 60% of that exerted by the mass of the reciprocating parts, as the engine speed increases the forces generated by the rotating parts increases at a greater and greater rate and eventually equals the force being generated by the reciprocating parts. If engine speed continues to increase the forces generated by the rotating parts will exceed the forces generated by the reciprocating parts. The forces mathematically only equal each other at a single engine speed. We want that speed to be close to the operating speed.

On a single the forces at 90deg to the cylinder bore are unopposed regardless of the % used as there is no force generated by reciprocating parts to oppose them. 90deg V-twins are wonderful.

Frits Posted an extract from Tony Foale site about counter balancers

Here

You may, Husa. The picture below may give a first impression, and you'll find the whole story here: http://www.tonyfoale.com/Articles/EngineBalance/EngineBalance.pdf (http://www.tonyfoale.com/Articles/EngineBalance/EngineBalance.pdf)
282158


Another thing to consider is fueling can be less fraught if it isn't being vibrated about too much.



You dont need a balance shaft in a single 2T as plenty of them have been made with no issues of vibration at all.
In a parallel twin you need one if firing at 90* like Harolds KTM as this reduces the rocking couple cancellation action of a 180* firing.
But yes a balance shaft has been used in things like RS125s from Honda, and these are set up to cancel the unbalanced portion of the reciprocating mass.
Take the shaft out and rebalance with Mallory and are they faster - yes.
Add some more Mallory to create a higher inertia crank assembly without affecting the balance and are they faster - yes.
Just a bit more to think about.

I await The Dutch corospondents reply.

[F5 Dave]

Honda MB100s have a balance shaft. I have removed the balance shaft in one motor and rebalanced the crank. The balance shaft rotated in the opposite direction to the crank at the same speed. It assisted the crank counterweight in offsetting the forces in line with piston motion but opposed the counterweight effects at 90debrees to bore centreline. Obviously I had to increase the crank counterweight which I did by drilling a couple of holes in each web, one each side of the big end. It buzzes a bit at odd speeds and you have to be careful how the engine is mounted to reduce harmonics.


I pretty much copied Mike here with a different frame and buzzes a bit somewhere maybe between 4000-8000 (not all of it) but I should never be there & over 30min race I never noticed vibration, so its great at race revs.

[Farmaken]

Wobbly, what is the total weight difference between a std. RS crank and a "heavy " version with heavy bar inserts. Cheers....

[Frits Overmars]

Top:-------------- Cranks 50% plus Balance Shafts 50% going down together cancels the Pistons 100% coming up.
Mid going down: Cranks 50% cancels Balance Shafts 50% as they are now pulling in opposite directions.
Bottom:---------- Cranks 50% plus Balance Shafts 50% coming up together cancels the Pistons 100% going down.
Mid going up:--- Cranks 50% cancels Balance Shafts 50% as they are now pulling in opposite directions again.You understood completely.


To do this the Balance Shaft has to rotate twice as fast as the crank.Or so I thought :facepalm:.

I don't expect to find a balance shaft turning at twice the crankshaft speed on a two-stroke single. And if I did, I would hope to find two of those shafts instead of just the one. Auto manufacturers trying to make their four-inlines run like straight sixes sometimes employ twin balance shafts turning at twice the crankshaft speed. But we like to keep things simple (and affordable).
Anyway, one balance shaft rotating at the same speed as the crankshaft, but in the opposite direction, will already do a lot of good. Let's forget about the con rod effect for now (assuming its length is infinite), then we can balance the total reciprocating mass by putting 50% counterweight in the crankshaft and the remaining 50% in the balance shaft.
A lot of fuzz is made over measuring this total reciprocating mass, but it's dead easy: see the picture below.
Note that the con rod is completely horizontal and that the gudgeon pin with its bearing, the cir-clips, the piston rings, are all fitted.
Now if you want a 50% balance factor, replace everything attached to the con rod small end with so much mass (a wire hook with a collection of nuts or washers, for example) that the scales read 50% of their original value. Attach that wire hook loaded with nuts to the con rod small end and then figure out the amount of material that you have to remove from or add to the crankshaft, so it will remain at rest in any position.
309190

Now here's a little teaser. Suppose we've found the optimum balance factor for a certain single cylinder engine without a balance shaft. A lower balance factor would increase the vibrations, as would a higher factor.
Now we fit a lighter piston. This means that the balance factor will increase. But the engine will vibrate less...

[Martin1981]

Thanks for that Frits. Can you please add a picture of THIS procedure: "Attach those nuts to the con rod small end and then figure out the amount of material that you have to remove from or add to the crankshaft, so it will remain at rest in any position." i just cn not imagine how this would look like.

sorry frits, i think i understand the most of what you are explaining. but that crankbalancing still makes me a little sick

[Frits Overmars]

Thanks for that Frits. Can you please add a picture of THIS procedure: "Attach those nuts to the con rod small end and then figure out the amount of material that you have to remove from or add to the crankshaft, so it will remain at rest in any position." i just can not imagine how this would look like.My pleasure Martin. Take a look at the above picture. Jot down the scales' reading, remove the piston from the con rod, let the con rod rest on the scales again and add a wire hook and a collection of nuts or washers to the scales until the reading is what you want it to be (50% of the original weight in the above example).
Attach the wire hook with the nuts to the con rod's small end and let the crankshaft rest on two beams, like in the picture below. First make sure that the beams are exactly horizontal by putting a piece of tubing (or a bottle) on them and adjusting their heights until the tube does not want to roll any more.
309191

Now if we put the crankshaft on the beams, it will probably roll until the bob-weights are either at the highest or at the lowest point, in which case we will have to add or otherwise remove material from the bob-weights.
Let's assume that the bob-weights move to the lowest point. Then we add extra weight (some more nuts or washers) to the wire hook until the crankshaft will stay in any position on the beams without a tendency to turn. We have now created the torque that is necessary to keep the crankshaft in equilibrium.

Example: We have an engine with a stroke of 54,5 mm. And we had to attach 80 grams of extra weight to the hook in order to reach equilibrium.
This weight acts via the con rod on the crank pin radius (half the engine stroke), so it generates a torque of 80 * (54,5 / 2) = 80 * 27,25 = 2180 gram*mm.

The bob-weights had a tendency to move to the lowest point, indicating that they are too heavy, so we have to drill holes in them.
The total mass of these holes, multiplied by the distance from the holes' centers to the crankshaft center line, also generates a torque.
Let's assume that we can drill a hole in each bob-weight sidewall, opposite the crank pin, with its center 35 mm away from the crankshaft center line.
In order to generate the same 2180 g.mm torque, the total mass from these holes must be 2180 / 35 = 62,28 gram.

One hole in each bob-weight, that's two holes in total. One hole should then equal 62,28 / 2 = 31,14 gram.
The specific mass of steel is 0,00785 gram / mm³, so the volume of each hole must be 31,14 / 0,00785 = 3967 mm³.
Let's assume that each bob-weight has a thickness of 20 mm. That is how deep we can drill (through and through).
Then the cross-section area of each hole must be 3967 / 20 = 198,35 mm².
Its diameter must then be SQRT (198,35 / (pi/4) ) = SQRT ( 198,35 / 0,7854 ) = SQRT (252,55) = 15,9 mm.

Obviously the further away from the crankshaft center line you can drill these holes, the smaller they need to be.


sorry Frits, i think i understand the most of what you are explaining. but that crankbalancing still makes me a little sickPiece of cake, isn't it?

Now how about that teaser? Any takers?

[cotswold]

Here is where TZ showed me how to balance my GP125 crankshaft after rebuilding it we used 50%

[Frits Overmars]

Here is where TZ showed me how to balance my GP125 crankshaft after rebuilding it we used 50%Very nicely illustrated. I would have used those pics if I'd had them :yes:.

[Martin1981]

Thanks Frits and Cotswold!

Got it now.

[speedpro]

For a TS 125 Suzuki to rebalance for bucket racing, ie revving the nuts off it, take a look at the picture of the GP crank above. The TS crank is similar in that it has 2 holes in each web. In the TS case the holes are different diameters. All you need to do is press a slug of aluminium into the larger hole on each web. No maths, no measuring, just do it. I figured with my TS years ago that it vibrated at revs(bad enough to cause bits to fall off the bike) because the counterbalance was too large so I added weight opposite. Worked so well that as soon as we fired it up on Pete Sales dyno he commented without me telling him I'd done it.

[speedpro]

In my opinion it is such an inexact operation, in that all frames are different, cylinder geometry relative to the frame, and the "realities" of use that a good educated guess of which way to go is all that's needed. Give it a try and make another adjustment. So far so good for me. On 2 stroke singles anyway.

[wobbly]

The so called "heavy " cranks for an RS125 Honda be they from the A Kit or from VHM are not in fact heavyer - they are lighter.
But the added Mallory metal near the crank wheels circumference adds considerable inertia.
There are alloy plugs in the blank areas near the wheels middle radius,and this reduces the actual mass.
Here are the old Rotax 256 with porkchop cranks, and the later Aprilia - both will have around the same balance factor,but the Aprilia has way higher inertia
with all that heavy metal added at the circumference.

Re the lighter piston scenario - this will effectively increase the balance factor so the peak forces in the plane of the cylinder axis will be reduced.
Thus less vibration in the critical vertical plane of the handlebars - but, by increasing the factor it will now vibrate more horizontally - usually not so much of an issue.

[lodgernz]

Phil Irving tuning for speed........
google has it
http://tuningforspeed.com/files/Tuning_for_Speed.pdf.


Fascinating reading is the chapter on 2-strokes. Phil may not have realised it, but he was documenting the dawn of the modern 2T engine, the point when it all changed.
Reed valves, disc valves, expansion chambers, squish bands, boost ports were all being experimented with. All that appears to be missing from his list is the A and B-transfer design.
Port timings were rather different: Ex duration of 140*, transfer 120*. Not much blowdown.
Interestingly though, he already understood STA was important, although he didn't use that name and gave no details.

[senso]

Regarding the crank balance, what a beautiful explanation!
Now I sort of understand, so beware, I will bombard this forum with doubts, as I have been running my crm 50 engine without the balance shaft(the engine revs up and down a lot faster, but does it vibrate, already broke a lot of supports due to vibration :rolleyes: )

Sorry for the long long delay in posting more photos of the cylinder cut-out, but here they are.
Around the A transfers the exhaust port has about 5mm of solid casting, there is 3-4mm of clearance between the holes that put coolant in the bottom of the exhaust duct, so I will enlarge mine to 7 or 8mm for better "flow", I hope the photos are clearer, but well they got out a bit blurry, I can take more if needed.

309198

309199

309200

309201

309202

309203

[senso]

And the rest of the photos, there is a good volume of coolant under the exhaust duct, but there is only two 5-6mm holes connecting them to the rest of the cooling jacket, I think there is some flow promotion because one of the holes is right in front of the coolant entry in the cylinder, so there might be some sort of venturi effect making it flow, so enlarging the holes to around 7-8mm might be a good idea:

309204

309205

309206

[TZ350]

Eeeek I have gone blind, everything is black, help how do I get back to the light side??????

[Grumph]

Fascinating reading is the chapter on 2-strokes. Phil may not have realised it, but he was documenting the dawn of the modern 2T engine, the point when it all changed.
Reed valves, disc valves, expansion chambers, squish bands, boost ports were all being experimented with. All that appears to be missing from his list is the A and B-transfer design.
Port timings were rather different: Ex duration of 140*, transfer 120*. Not much blowdown.
Interestingly though, he already understood STA was important, although he didn't use that name and gave no details.

i've got his Two - Stroke Power Units, published 1967 which covers a lot more ground. When he was out here in the '80s i remember him being asked about updating his books.
I think the answer was along the lines of "I'm out of touch now, let someone else have a go" and Bell and Robinson carried it forward.

Next up, Thiel and Overmars......Please!! Failing that, someone do the collected observations of Chairman Wob....

[Grumph]

Eeeek I have gone blind, everything is black, help how do I get back to the light side??????

No idea what you were looking at but I was seeing it on a black background, now blinding white....Swap you.

[wobbly]

I like being white

[TZ350]

someone do the collected observations of Chairman Wob....

There is an option in "Thread Tools" for down loading the complete text of this thread.

[F5 Dave]

Site upgrade. Mods being added in a day or so. Bottom left corner i think the dark universe option will appear again. I hope.

[jasonu]

Eeeek I have gone blind, everything is black, help how do I get back to the light side??????

Happened to me too. An hour later and normal service has been resumed.

[husaberg]

No idea what you were looking at but I was seeing it on a black background, now blinding white....Swap you.

Shit I just posted a thread asking why and where has the dark zone option gone.....It was under general settings.

oh I see..
http://www.kiwibiker.co.nz/forums/showthread.php/173249-Site-software-upgrade-to-vB4-2-2

[jasonu]

Shit I just posted a thread asking why and where has the dark zone option gone.....It was under general settings.

oh I see..
http://www.kiwibiker.co.nz/forums/showthread.php/173249-Site-software-upgrade-to-vB4-2-2

Na mate something funky happened. All options disappeared then came back.

[Grumph]

There is an option in "Thread Tools" for down loading the complete text of this thread.

I'm elderly and on slow dialup, i doubt I'd live long enough to print out the entire thread....And just picking Wob's posts, it doesn't as far as i can see anyway, give the full reply/post just the first couple of lines. Context is important too, someone should spend a week or so sorting the questions and answers...You've created a monster.

[husaberg]

I'm elderly and on slow dialup, i doubt I'd live long enough to print out the entire thread....And just picking Wob's posts, it doesn't as far as i can see anyway, give the full reply/post just the first couple of lines. Context is important too, someone should spend a week or so sorting the questions and answers...You've created a monster.

you don't print it you save it, (took less than 30 seconds for me on a set up worse than 50 per cent of nz has)then you put it in word use an advanced find, to search the key words for which ever topic you wish to separate out.
Then you sift through. Sort the wheat from the chaff.
If it was to be done it would need some sort of frame work to start from.
Say a previous book.

12v water pump epic output
https://www.12volt.com.au/
Circulation Pumps

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Not self priming - install below the liquid source.

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Jabsco Cyclone Circulation Pump
PUJCY12V Cyclone 12v $539.00
https://www.12volt.com.au/General%20Htmls/webcat2003/pumps%20pics/jabsco_cyclone.jpg

12VDC 8A Dimmer / Motor Speed Controller

DC speed controllers are ideal for slowing down pumps and motors or dimming lights but commonly use resistance circuits and are very inefficient.

The pulse width modulation (PWM) used in this controller allows you to vary the output from 0 to 100% while maintaining a very high efficiency.

When used on motors this ensures full torque is available at very low speed and the motor won't shudder at start-up.

Operates on any 12VDC system and capable of controlling devices rated at up to 8 amps.

The internal circuitry is fully potted and the control potentiometer is splash proof making this suitable for marine environments and other harsh conditions.


Dimmer / Motor Speed Controller
MP3209 8A 12VDC dimmer $39.99

[TZ350]

Carburetors are great because of their analog ability to change the fuel delivery with changes in air flow at the same throttle setting.

EFI, well EFI is not forgiving at all.

309236 16 Alpha-N map lines with most of them concentrated in the upper power area of the graph.

Back to the EFI thing. The Ecotrons Alpha-N map has 16 rows to work with and I had concentrated them in the area where the power is, as you do. Well that turns out to be a mistake because there is not much difference in fuel demand per cycle between 100% throttle and 90 or 80 or even 70 at max power and virtual no difference at all above 40% in the 3 to 6000 rpm range.

The big jumps were between the lower throttle settings where there was not much excitement happening, well the mistake is that the CPU has a hard time bridging the big gaps below 40% especially when it is also trying to swap between low and high injectors at the same time.

309235 16 Alpha-N map lines more evenly spread so as to not have any big jumps between them.

Under 35% throttle is pretty unexciting power wise but on the track its a big deal as far as on track drive-ability is concerned. So for the next attempt I am going to use more Map lines in the lower area where things are changing rapidly with throttle position and less in the upper area where things are not changing so much, the power at 80% throttle is not very much different to 100%.

As it turns out, it was a mistake to concentrate my map in the power area, but I guess I will forgive myself..... :laugh:

[Frits Overmars]

Carburetors are great because of their analog ability to change the fuel delivery with changes in air flow at the same throttle setting. EFI, well EFI is not forgiving at all. I'd say EFI won't get fooled by changes in inlet timing, reed stiffness, etc; it will keep doing as it is told - by you.


As it turns out, it was a mistake to concentrate my map in the power area.I would not consider it a mistake at all. It was a ride up the learning curve. Will calling it an experiment make you feel any better?

[Frits Overmars]

Now here's a little teaser. Suppose we've found the optimum balance factor for a certain single cylinder engine without a balance shaft. A lower balance factor would increase the vibrations, as would a higher factor.
Now we fit a lighter piston. This means that the balance factor will increase. But the engine will vibrate less...

the lighter piston will effectively increase the balance factor so the peak forces in the plane of the cylinder axis will be reduced. Thus less vibration in the critical vertical plane of the handlebars - but, by increasing the factor it will now vibrate more horizontally.When I started reading Wob's reaction, my first thought was: "I should have excluded Wayne from the answerers. He's too good; let the others have a go first".
But I'm glad I didn't. You fell for it, Wob!
You are of course 100% right about the reduced peak forces in the plane of the cylinder axis and the reduced vibration in the critical vertical plane of the handlebars.
But fitting a lighter piston will not cause stronger horizontal vibrations. Yes, the balance factor has increased, but that is just an arithmetic quantity; it's not a force.
The crankshaft's bob-weight masses haven't changed, so neither have the fore-and-aft forces.

How far can we go with lightening the piston (leaving mechanical strength aside)?
Suppose we have a 200 gram piston and a 50% balance factor. So the bob-weights generate a force of 100 gram (OK, 1 Newton. And yes, all these forces will be umpteen times larger than 100 gram because of inertial effects, but that does not alter their mutual ratios, so I'll leave the rpm aside and just quote the weights).
There will be free vertical forces of 100 g upward and 100 g downward, and there will be free horizontal forces of 100 g forward and 100 g rearward.

Let's fit a 150 gram piston. That means the balance factor will become 66,7% (100 g bob-weight force / 150 g piston force). The free upward and downward forces will be 150 -100 = 50 g; half of their original values. The free horizontal forces remain unchanged at 100 g.

Now let's fit a piston that weighs only 100 gram. The balance factor becomes 100% ; the upward and downward forces are completely neutralized by the bob-weights, so the vertical vibrations are completely gone. The horizontal forces remain unchanged at 100 g.

Only when we fit a piston that's so light that the balance factor rises above 100%, will the free vertical forces start returning - but now in the opposite direction.
Now it's no longer the piston that causes vertical vibrations; it's the bob-weights. That is because the vertical forces generated by the bob-weights are no longer completely counteracted by the vertical piston force. And those bob-weights also keep causing their original horizontal vibrations.
The chances of fitting a piston that weighs less than half of the original piston are slim. However, my friend Dolph van der Woude designed a beryllium piston that would do the trick....

[wobbly]

Thanks Frits, its the case of the smarty pants ( clever clogs ) sucks in, the big mouth.
Think before spouting would do some good, as of course the bob weight hasnt changed so the horizontal force is still the same as previous.

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/Hq9X0MEMtag" frameborder="0" allowfullscreen=""></iframe>

2T dyno porn.......

<iframe width="420" height="315" src="https://www.youtube.com/embed/Kfx61bUOznc" frameborder="0" allowfullscreen=""></iframe>

EFI 125 .....

Like mine it runs well at high rpm and has good throttle response in the high power high rpm area but we don't get to see if it has on track drivability, Ie good low throttle lower rpm responsiveness.

[TZ350]

<iframe width="420" height="315" src="https://www.youtube.com/embed/b1YbPdw00Ww" frameborder="0" allowfullscreen=""></iframe>

This one seems to have more throttle response.

<iframe width="560" height="315" src="https://www.youtube.com/embed/7AHJZzW5_bw" frameborder="0" allowfullscreen=""></iframe>

Initial start of the Yamaha 600cc Two stroke twin snowmobile engine project with custom fuel injection system.
2013 Students built this project from scratch in 2 months using the Performance electronics ECU, R6 throttle bodies, Toyota camry crank trigger wheel, MT01 gas tank. Running COP coils, 45 PSI rail pressure and Vector driveline. This project will be the test bed for a future closed loop fuel injection system using type K EGT probes.


2T LPG fuel injection:- http://youtu.be/4AAw-H_A93I

Development of an autonomous model based real time controller for a LPG fuelled two stroke barrel injected SI engine http://youtu.be/JexgKNrg01w

DIY Electronic Fuel Injection EFI 2 stroke:- http://youtu.be/WHXl9hI1bj4

Mercury 2.5L 2T EFI dyno Test:- http://youtu.be/Zj7aO2DFvE8

Ultra compact micro fuel injection system for small capacity 2-stroke engines. http://youtu.be/vZ88vqAy3cM

motore a 2 tempi con iniezione diretta DFI... http://youtu.be/XIcX9-GsMGQ

Simulations of Direct Fuel Injection:- http://youtu.be/PPOVgaJjQLg

[jonny quest]

OEM tuners on tps go like... 0 4 6 8 10 12 18 25 35 50 60 70 80 (roughly). When you start getting over 33% tps the throttle blade open area doesn't change as drastically. Google Honda PGM CRF tuner and view pics. I'm sure you'll find the tps % they use.Probably a good start point

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/E90a3RpQ6R4" frameborder="0" allowfullscreen=""></iframe>

EFI RS125

"Second start up of the Cougar Red Honda RS 125 GP bike.
New Ignijet 2008 ECU and wiring loom by myself. 3 injectors.
YES THIS IS FUEL INJECTED!!! Also running Bio fuel E85.
Lots more set up on the dyno. But initial runs look promising.

This project has been on going for many years. From the carburated version way back in 2008.
Stood dormant for nearly 2 years after hitting a brick wall with the previous ECU the guys decided it was time was to finish it off.

I suggested the Ignijet ECU and away it went. For more information about the machine and its past:- www.cougarred.com "

[TZ350]

OEM tuners on tps go like... 0 4 6 8 10 12 18 25 35 50 60 70 80 (roughly). When you start getting over 33% tps the throttle blade open area doesn't change as drastically. Google Honda PGM CRF tuner and view pics. I'm sure you'll find the tps % they use.Probably a good start point

Thanks, I will follow that up, not being much interested in slow running I had mine virtually the other way around, turned out to be a mistake.

[peewee]

frits if you happen to talk with jan tell him thnx. some of what he did im gonna use in my engine :2thumbsup. its not the easiest thing adding extra ports that were never intended to be there but in the end i think it will have nearly 2x more power

[husaberg]

Carb manifolds
http://www.jetsrus.com/mounting_flanges/mounting_flanges.html
http://www.allensperformance.co.uk/products-manifolds.html

[Frits Overmars]

Regarding the crank balance, what a beautiful explanation! Now I sort of understand.Thanks Senso. You may want to re-read it because I just re-wrote it, hopefully improving a bit on my explanation: http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130833843#post1130833843

[Flettner]

Frits, out of interest, what alloy did you get your cylinders cast / sintered in?

[Frits Overmars]

Frits, out of interest, what alloy did you get your cylinders cast / sintered in?AlSi12


The page at www.kiwibiker.co.nz (http://www.kiwibiker.co.nz) says:

The messager you have entered is too short. Please lengthen your
message to at least 10 characters.

Now what else could we put into the alloy in order to lengthen its name without influencing its properties?

[F5 Dave]

Chilli. Makes everything taste better.

[Flettner]

AlSi12



Now what else could we put into the alloy in order to lengthen its name without influencing its properties?

Thank you. Similar ish ( silicon content ) to LM13, then that is what I will use, as I have a stack of it.

[crbbt]

Sorry to bother everyone.

My forum participation is too low to send privet messages.

These dimensions for a Honda RS125. are they standard or kit?

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301482&d=1411381933

If Frits is going to answer (simple yes or no). here are some responses to copy and paste:

Yes, they are Kit

No, they are standard

[Frits Overmars]

My forum participation is too low to send privet messages.I remember the problem, but it hasn't bothered me lately :whistle:.


These dimensions for a Honda RS125. are they standard or kit? First they were works Honda NSR250, then they became Honda RS250 kit and RS125 kit, then they became standard.
Then they appeared on the works reed valve Derbi 125 (tuned by Harald Bartol). Then they appeared on the 125 and 250 cc works KTMs (tuned by Bartol).
Then they appeared on the KTM production racers.
Then Dorna & Honda killed two-stroke GP-racing, so the 250-twins could not make the 600 cc sixteen-valvers look ridiculous and the 125-singles could not do the same to the 250 cc four-valvers.
309357 309358

[sonic_v]

Thank you. Similar ish ( silicon content ) to LM13, then that is what I will use, as I have a stack of it.

From this table, LM6 would appear to be the closest equivalent.

http://www.cast-alloys.com/products/lm_chart.htm

[Frits Overmars]

From this table, LM6 would appear to be the closest equivalent.

http://www.cast-alloys.com/products/lm_chart.htmThe difference between LM6 and LM13 that struck my eye was the Cu content. Better check with you nikasil-provider whether that's acceptable, Neil.

[richban]

I remember the problem, but it hasn't bothered me lately :whistle:.

First they were works Honda NSR250, then they became Honda RS250 kit and RS125 kit, then they became standard.
Then they appeared on the works reed valve Derbi 125 (tuned by Harald Bartol). Then they appeared on the 125 and 250 cc works KTMs (tuned by Bartol).
Then they appeared on the KTM production racers.
Then Dorna & Honda killed two-stroke GP-racing, so the 250-twins could not make the 600 cc sixteen-valvers look ridiculous and the 125-singles could not do the same to the 250 cc four-valvers.
309357 309358

Thats really interesting. I have been looking at RS250 pipes for my NSR300. They seam to be the go to for so many 125's and 250's. A timely post. I am pulling the 300 down soon to give it a top end freshen up and (TRY) to make some pipes. I will post some pic's as I get going.

[RAW]

:bleh::bleh:Then Dorna & Honda killed two-stroke GP-racing, so the 250-twins could not make the 600 cc sixteen-valvers look ridiculous and the 125-singles could not do the same to the 250 cc four-valvers.
309357 309358[/QUOTE]

Great Quote Frits.
Deep down real 2 stroke enthusiasts will prevail :bleh::bleh:

[Dutch Fisher]

I remember the problem, but it hasn't bothered me lately :whistle:.

First they were works Honda NSR250, then they became Honda RS250 kit and RS125 kit, then they became standard.
Then they appeared on the works reed valve Derbi 125 (tuned by Harald Bartol). Then they appeared on the 125 and 250 cc works KTMs (tuned by Bartol).
Then they appeared on the KTM production racers.



Now now Frits your surely not saying that the later half of Harold Bartols career was little more than a plagiarizing exercise involving paying a poorly paid mechanic from a team that ran A-kit Honda equipment the equivalent of say US$3500 to either accuately measure pipes and cylinders or indeed arrange a hour or so of time for an associate of the afore mentioned Herr Bartol to have in hand the afore mentioned A-Kit cylinders by which the associate may if he so wished to take a silcon cast mould of transfer and exhaust shapes and angles.

How dare you Sir !!

That is a bit like saying in 1999 that Yamaha did such a similar act of midnight espionage with the assistance of a similar poorly paid mechanic for the exchange of a similar fiscal amount (adjusted for inflation) in time to power their champonship winning Y2K 250 racing motorcycle and then produce a fabrication of a story that hints at their success being down to a newly acquired Chech made CNC controlled anemometric-tester machine and a change to 54/54mm bore/stroke ratio that is it just so happens to share with say an A-Kit Honda.

I myself will not hear of such a thing in the arena of sporting gentleman where honor and valour are upmost and peeking over an opponents shoulder would never enter the mind of such esteemed competitors. :whistle:

[wobbly]

I dont get what the issue is here.
The A kit pipe dimensions were published by Honda very early on, and those dimensions were used by Harold,when he was developing his own cylinders whilst still working for the Yamaha 125 effort (with Ui ).
In fact talking to him at the time it was almost as if he was proud of the fact that he had used the same pipes for 3 years or so.
I offered to do something better, but was politely told no thank you.
And as Frits says, those same dimensions then went to Derby, where later Jan blew Harolds best work into the weeds.
Then those same pipes appeared on the KTM, a superbly conceived piece of engineering, but certainly not the fastest - again I thought it a travesty that those old dimensions were stuck to for some weird reason.

Then we have another rant about the champ winning Yamaha 250.
That engine used the new cylinders developed for the 500, and that certainly derived its performance from what the engineers learnt from the Czech machine ( Bud Askland got one first when tuning for Kenny/Rainey )plus the conversion to 54/54 - that was an obvious need.
Honda had no more influence on any of this than say Aprilia did, it just became obvious that sticking with corporate pride and a 50.6 stroke was dumb from the start.
Sure it was a very complete, well developed machine, but after years of the TZ being laughable, it for sure was the new technology in the 250 engine that made the real difference - with the addition of the superb Yamaha developed spool valve from the ancient YPVS.
Whats the problem.

[kel]

another rant about the champ winning Yamaha 250.

Good old Yamaha, but then “Imitation is not just the sincerest form of flattery - it's the sincerest form of learning.” They really should have credited Honda in the references though

[Frits Overmars]

“Imitation is not just the sincerest form of flattery - it's the sincerest form of learning.”I must disagree Kel. If you perfectly copy a perfect solution, it will work perfectly but you won't have learned anything.
I keep saying: "Everybody has to make their own mistakes". That means 'gather experience'.
But I also say: "Try to learn from other people's mistakes because you won't have time to make them all yourself". That means 'Listen. Look. Read. Get an education'.

[seattle smitty]

Motor-racing is fascinating partly because it has many components, many subtleties. If the competition only consisted of "dyno-racing" engines against each other, the various engine questions that are covered in this thread would pretty quickly be settled. But instead, the racing involves riders/drivers on bikes/karts/boats/sleds/etc. powered by engines, set up by tuners of engines. The best engine doesn't always win. Nor does the best rider, nor the best bike.

Bearing on the study, knowledge, practice, and experience called for above, is applied intelligence (alas for me!). In reading about Kenny Roberts, for one example, I've been struck by his ability to analyze a track, the ways he can set up his bike to work with the track, and the ways he can ride the track to gain an edge over competitors, whom he also studies. He didn't win on sheer natural ability; there were others more talented. (I never met Roberts, who used to have a reputation as a "prickly" individual, but I like him because he is not just a rider but an all-around RACER who can weld and run machinery and build his own equipment. A.J. Foyt is another such).

Motocrosser Bob Hannah said the same of himself, that he had to out-think others to win. After leaving motocross, Hannah did some air racing at Reno, and now flies bush planes for fun. But he hasn't stopped thinking. His wife tells of riding along over wild country and suddenly challenging him by suddenly saying, "Engine out, where do you put us down?," and every time Hannah will instantly point out the window and say, "There!," and tell her why, because he is always watching the terrain and thinking about it.

Maybe some of you have read Keith Code's books on improving your riding and racing. He also make a strong case for bringing intelligence to bear on the problem. It is good to get plenty of track time, says Code, plenty of practice, but it is far better that you get GOOD practice, intelligent practice. Don't just ride the track, THINK about it, test ideas, have goals, figure out what's happening and why, get the most out of the practice.

Much of the fun of this thread is watching everybody applying their own intelligence, crunching information in their cranial computers, trying to figure things out.

( blah, blah, blah . . .)

[Yow Ling]

I must disagree Kel. If you perfectly copy a perfect solution, it will work perfectly but you won't have learned anything.
I keep saying: "Everybody has to make their own mistakes". That means 'gather experience'.
But I also say: "Try to learn from other people's mistakes because you won't have time to make them all yourself". That means 'Listen. Look. Read. Get an education'.

Sucess is a poor teacher

[Grumph]

Sucess is a poor teacher

It pays the bills and keeps sponsors happy though...and may just get you enough time and money to do the experiments you have lurking in the back of your mind.

[Frits Overmars]

Sucess is a poor teacherRight you are, Yow Ling. It only taught me that champagne and contact lenses don't go well together.

[peewee]

hey guys sorry if this is a dumb question but whats the easiest way to tell if a crankshaft is forged or cast ? ive heard you can easily tell by the parting lines where the molds or dies meet but from looking at the couple cranks i have in the garage it doesnt appear theres any parting lines, so im thinking they must have been on the circumference of the wheels. since the circumference of the wheels are machined , any parting lines would be gone. i have a few cylinders sitting around and the parting lines from the cast molds are easily seen but the crankshafts i have i dont see these lines. thats why im guessing they were at the circumference of the wheels which have been machined as the final procedure during manufacture. from what ive read (and seen on cylinders) cast will have thin sharp parting line. forged will have wider dull parting lines. but like i said, how do you tell what crank it is if there is no visual parting lines ?

[crbbt]

Thanks for the response Frits!

More information than I could have hoped for.

One of the mechanics on the weekend at philip island reckon he could wind up the 125 to blow the moto 3's away! I don't yet have the ability to keep on it.

[TZ350]

Sucess is a poor teacher

309388

"Failure" I must have a good teacher, because I now know far more about running a 2T with EFI than I wanted to ..... :laugh:

[Dutch Fisher]

Right you are, Yow Ling. It only taught me that champagne and contact lenses don't go well together.


Frits you are supposed to drink it, not pour it in your eye

[RAW]

Various copies of Jans aprilia exhaust port profiles

[Frits Overmars]

Various copies of Jans aprilia exhaust port profilesMaybe you swapped the DEA and VM captions?

[oktrg500]

Hi,

The following I'm unable to understand. The subject in speak is the air box for the Aprilia RS 125 streetbike. Reliable sources has reported several times about loss of power when the 'snorkel' is removed. I'd like to understand why. Understanding why, would be valuable when trying to figure out if the std design can be improved upon. Attached is an exploded view of the box, which I've tested holds 2,4 liter of water. And a back to back test in the dyno from the internet with and without the snorkel.

[senso]

Too much air is sucked by the engine and because there is no re-jetting the engine is lean, maybe..

[Yow Ling]

Hi,

The following I'm unable to understand. The subject in speak is the air box for the Aprilia RS 125 streetbike. Reliable sources has reported several times about loss of power when the 'snorkel' is removed. I'd like to understand why. Understanding why, would be valuable when trying to figure out if the std design can be improved upon. Attached is an exploded view of the box, which I've tested holds 2,4 liter of water. And a back to back test in the dyno from the internet with and without the snorkel.

http://en.wikipedia.org/wiki/Helmholtz_resonance

[F5 Dave]

lean if no rejet of course.

& the entry to the box without the snorkel is horrible flat edges.

[lodgernz]

I have got R7376 several times for around 35USD, about 1/3 of the cost of the shorty Honda style.
And I would never use an Iridium plug again in a real race engine.
They seemed like a great alternative till we lost several engines in a row, including dropping an earth electrode on
the last corner of the last lap - to take a 125 kart title 3 in a row.
The Iridium centre ceramic will crack and fall off the instant you see even the smallest amount of deto, and the reason the R 7376 style plugs are expensive is that the rare
earth ground strap is laser welded to the body - I have never seen or heard of one failing, and the ceramic can crack occasionally, but again I have never seen one drop out.
Its one of those things, just accept that you pay for what you get, and buy the best when it really matters.

Wobbly, I'm a little confused by your post above. You are critical of Iridium plugs, and advocate the use of the R7376.
Now I see, in the NGK plug specification chart at http://www.ngksparkplugs.com/docs/RacingSpecs2013.pdf
that R7376 has an Iridium centre electrode.

When you criticised the Iridium plugs, were you talking about the sales name of that range, rather than the electrode metal?

[RAW]

Maybe you swapped the DEA and VM captions?

No Frits, definetly not. The DEA cylinder is an early one without the dimples, the VM is a copy of DEAs later model cylinder.

Posting incorrectly on purpose would be poor form

[wobbly]

Plain old Iridium plugs are a brand name, and yes they have Iridium fine wire centre electrodes.
As I said, these will drop the ceramic at the slightest provocation.
The R7376 has the Iridium centre, but also has a Platinum earth fine wire strap.
The construction is completely different, and is dead reliable.

So whats the go with Dutch Fisher then.
Coming on here and slinging shit at Frits over historical issues that i then expand on somewhat,with facts I know are accurate as I was actually there at the time, and he goes deathly silent on the subject.
Frits ignores it completely, that probably gives the posting the recognition it deserves.

[lodgernz]

Plain old Iridium plugs are a brand name, and yes they have Iridium fine wire centre electrodes.
As I said, these will drop the ceramic at the slightest provocation.
The R7376 has the Iridium centre, but also has a Platinum earth fine wire strap.
The construction is completely different, and is dead reliable.


Thanks Wobbly.

[ken seeber]

So whats the go with Dutch Fisher then.
Coming on here and slinging shit at Frits over historical issues that i then expand on somewhat,with facts I know are accurate as I was actually there at the time, and he goes deathly silent on the subject.
Frits ignores it completely, that probably gives the posting the recognition it deserves.

Good one, was wondering what was going to happen with this. I, like many others I am sure, read his post with amazement and confusion as to what he was on about. He was certainly serious and pointed and fucking unnecessary. I am a relative newcomer to this forum, and like everyone else, am good at some things and dumb in other things. One thing I am good at is knowing what is unnecessary. That post on this thread was unnecessary to the point of being disgusting.
If DF hasn't realized it yet, this ESE thread, with all its incredible history, is primarily about engines and associated technologies, with a big share of it towards 2 strokes. It is supported, been contributed to and read by a very large group of like minded and interested people. Some or a lot of these people have incredible related knowledge and experience and, for the huge benefit of many, willing to freely to share it. This thing is a gem.

To come up with some form of amateur political crap like he did is total wank. So, DF, learn from your absolutely stupid mistake, one that could affect many, and if you dare to continue with this crap then I for one will be asking the administrators to tell you to fuck off forever

[2T Institute]

Hi,

The following I'm unable to understand. The subject in speak is the air box for the Aprilia RS 125 streetbike. Reliable sources has reported several times about loss of power when the 'snorkel' is removed. I'd like to understand why. Understanding why, would be valuable when trying to figure out if the std design can be improved upon. Attached is an exploded view of the box, which I've tested holds 2,4 liter of water. And a back to back test in the dyno from the internet with and without the snorkel.

That was on a friends RS and if I wasn't there at the time looking at the dyno read out (had a EGT on and there was NO increase in temp) I probably wouldn't believe it. Power came back with the snorkel reinstalled. The airbox seems to be a Rotax designed part common with the MAX kart and the RS, they are on the small side and I'm wondering if the snorkel makes the airbox seem bigger or just makes it do a better job.Sounds better without the snorkel but noise isn't hp. In the end we give up wondering and built a long rod stroker engine

[monkeyfumi]

I was under the impression that any snorkel or duct contributed to the overall airbox volume.
Given the RS125 airbox seems quite small, the volume of the snorkel might add a considerable % amount.

[F5 Dave]

and did anyone measure the lid in the volume? filter isn't effectively there. . . .actually, maybe it is part there.. ahh heck I struggle to care enough atm.

I'd still be pointing fingers at the nasty intake of a hole in a flat surface. A carb in the breeze draws air from all around it.

[ac3_snow]

Long time listener (lurker?) first time caller....

Thanks to the lads at the house of speed I finally got my AM6 (50mm malossi mhr replica barrel) powered TZ 80 onto the dyno tonight.....

First dyno chart below (red) came as a bit of a shock - 10HP!. A bit of fiddling with the ignition (PVL Go Kart analog) and leaning up the main pushed us out to 15HP pretty easily but as you can see the graph is horrid......

So, I hear there has been progress....
Very keen to see the results and know what the changes were.

[koba]

So, I hear there has been progress....
Very keen to see the results and know what the changes were.

Me too!
:woohoo::Punk::corn:

[lodgernz]

and did anyone measure the lid in the volume? filter isn't effectively there. . . .actually, maybe it is part there.. ahh heck I struggle to care enough atm.

I'd still be pointing fingers at the nasty intake of a hole in a flat surface. A carb in the breeze draws air from all around it.

I agree with Dave, it looks like the hole faces forward, on a 45* face. Air will tend to go right over the hole rather than through it.

[husaberg]

Plain old Iridium plugs are a brand name, and yes they have Iridium fine wire centre electrodes.
As I said, these will drop the ceramic at the slightest provocation.
The R7376 has the Iridium centre, but also has a Platinum earth fine wire strap.
The construction is completely different, and is dead reliable.

So whats the go with Dutch Fisher then.
Coming on here and slinging shit at Frits over historical issues that i then expand on somewhat,with facts I know are accurate as I was actually there at the time, and he goes deathly silent on the subject.
Frits ignores it completely, that probably gives the posting the recognition it deserves.

I think the dutch fisher may have been referring to this Jan Thiel quote. (which has been translated by google)



Yamaha was later returned to 5 transfer ports. Or rather they have the Honda cylinders copied!
Cees van Dongen was thus the first, he has a casting mold to make for Yamaha 125 of his son Jos with Honda flushing ducts and exhaust.
The casting mold was later sold Bartol, who then worked for Yamaha.
So therefore, in a roundabout way the Honda copy with Yamaha ended, They are there, in 2000, it became world champion.
So Bartol for Yamaha Honda copied, and later for Derbi KTM and done the same.



I think it the Dutch fisher was in more in jest maybe somewhat lost in translation.

[Frits Overmars]

So whats the go with Dutch Fisher then. Coming on here and slinging shit at Frits over historical issues that i then expand on somewhat, with facts I know are accurate as I was actually there at the time, and he goes deathly silent on the subject. Frits ignores it completely, that probably gives the posting the recognition it deserves.
Good one, was wondering what was going to happen with this. I, like many others I am sure, read his post with amazement and confusion as to what he was on about.I was under the impression that Dutch Fisher's comment was written tongue-in-cheek, so I did not take offence. I did try to guess who he is, if maybe I know him.
Is he really a fellow countryman? I'm sure he is grinning at all this, whoever he is. Maybe he will raise the vail now?
Anyway, Wayne and Ken, thanks for standing up for me.

[kel]

, and if you dare to continue with this crap then I for one will be asking the administrators to tell you to fuck off forever

Hmm.
I for one enjoyed the amusing tounge in cheek post.

[wobbly]

I think Jans translated comments are a little off base in that yes Bartols cylinder design he was working on when at Yamaha with the 125 race team were
very Honda - ish, in that it dumped the twin boost ports ( a good thing ) but went to a T port ( not so flash ).
His cylinder was quite alot faster than the 125 teams factory versions at the time, but Yamaha management would not allow the team to use them in racing.
Bartol may have used a Honda port mould, but he had access to a Czech machine ( very probably Cees ),as did Askland, and it was the results from this work,staring them in the face, that forced Yamahas hand to finally buy one and learn
how to interpret the results.
In Y2K year the Yamaha tech director told me that they could now predict the power delivery from a cylinder purely from the scavenging pattern shown on the Czech machine
and they had quit using a dyno to tailor the powerband for the 250 project.
Also that he was very grateful that management had insisted they use the spool powervalve, as they were acutely aware of the fact they could be seen to be "copying" the Honda
and Aprilia by going square bore/stroke and wanted to retain corporate " face " by using something very Yamaha - ish, and it just happened to work a treat.
I, as are many people, admire alot of Harolds work,but the proof is in the numbers, and Jan destroyed his dyno results at Derby, and then the KTM as stunning as it was in execution, was
hamstrung by odd decisions - the pipes being a good example.

[husaberg]

I think Jans translated comments are a little off base in that yes Bartols cylinder design he was working on when at Yamaha with the 125 race team were
very Honda - ish, in that it dumped the twin boost ports ( a good thing ) but went to a T port ( not so flash ).
His cylinder was quite alot faster than the 125 teams factory versions at the time, but Yamaha management would not allow the team to use them in racing.
Bartol may have used a Honda port mould, but he had access to a Czech machine ( very probably Cees ),as did Askland, and it was the results from this work,staring them in the face, that forced Yamahas hand to finally buy one and learn
how to interpret the results.
In Y2K year the Yamaha tech director told me that they could now predict the power delivery from a cylinder purely from the scavenging pattern shown on the Czech machine
and they had quit using a dyno to tailor the powerband for the 250 project.
Also that he was very grateful that management had insisted they use the spool powervalve, as they were acutely aware of the fact they could be seen to be "copying" the Honda
and Aprilia by going square bore/stroke and wanted to retain corporate " face " by using something very Yamaha - ish, and it just happened to work a treat.
I, as are many people, admire alot of Harolds work,but the proof is in the numbers, and Jan destroyed his dyno results at Derby, and then the KTM as stunning as it was in execution, was
hamstrung by odd decisions - the pipes being a good example.

I can't comment,as only posted what i had seen and what i thought was the Fishers intent, but with regards to design often similar solutions are arrived at because they represent the best solution anyway.
I just happened to have a word document open as i was looking for a quote from either Jan or Frits regarding Balance shafts. Then i noticed the one about the Honda, Yamaha,Bartol.
None of which I thought was derogatory, just a general observation.

With regards to balance shafts I am pretty Sure Both Frits and Jan favour them.
(Forgive me if I paraphrase from memory) The balancing of a crankshaft to whatever magic factor/figure with he counterweights, does not balance the engine. It only just moves the vibration it to someewhere else in the rev range less of a nusience or something like that. (remember Paraphrase from memory)
Pretty sure the reason a lot of Balance shafts may cost power (in some situations) is more to do with oil drag brought about by a poor choice of location (RSW125 this seems to be the case my own observation likely a Rotax carry over)
Often referred to as windage (oil is 600 times denser than air)
Frits 50cc design 'the balnce shaft high mounted with sealed bearings out of the way of oil(Maybe even under a vacum :rolleyes:)
My take is an engine construction is. if it is designed with a balance shaft, The engine design then can be made lighter (ie thinner wall thickness cases etc), also the balance shaft is also a potentially a convenient location to drive ancilleries such as water pumps. Maybe even a stator:shutup:

Personally i like the older style Husaberg balancer, that is almost disk valve like in appearance, Very clever and very original.
309410309411309412309413
Well first time i had seen it but it might be stream engine technology for all I know. Not that much is really new now.

I had a giggle the other day looking at a 1923 TT racebike (Works Douglas) Picture.
It had a very modern appearing front disk brake. With a caliper that was very much like a mornern cable operated Mountain bike caliper only finned.
309418309417

[Muciek]

Hi guys, Does anyone seen cylinder like this? (I hope Frits know something about this one) Is this some early rotax , or "home made " one? It's fitted in 51,6 stroke engine.


Here are pictures http://imgur.com/a/Sf6Pb

[TZ350]

.

Lots of 2T cylinder sleeving and Interesting workshop projects:- http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page46

[F5 Dave]

Just finishing reading Stan Stephens book, an autobiography it makes good reading. You won't pick up any tuning tips but that's not the point. There were a few bad words said about him a couple of hundred pages back here but I think they were unfounded. He's about 70 now & his success was earned from tuning production bikes within std parts restrictions. Mostly through serious hours on the dyno & fair play to that.

In your own book you do get the ability to paint things of your story without right of reply, but it does sound like he got spun up by a few of his employees effectively feathering their pockets. He's got a col in Cl Mtrcyc Mechanics mag & does some interesting projects like a large RZ500 with 350 barrels & currently a V6 RZ of some huge capacity. An entertaining writer, if probably by his own admission stuck in the 80s. But they weren't such bad years. And his CV of championships for supported riders makes for a hard stack to follow, at least at national & club level.

[2T Institute]

Hi guys, Does anyone seen cylinder like this? (I hope Frits know something about this one) Is this some early rotax , or "home made " one? It's fitted in 51,6 stroke engine.


Here are pictures http://imgur.com/a/Sf6Pb

Either home made or more likely all the rotax logos ground off .

[Frits Overmars]

Hi guys, Does anyone seen cylinder like this? (I hope Frits know something about this one) Is this some early rotax , or "home made " one? It's fitted in 51,6 stroke engine. Here are pictures http://imgur.com/a/Sf6Pb
Either home made or more likely all the rotax logos ground off .I don't know the engine but cylinder and head are clearly Rotax-inspired like 2T-I says. The cases look like CZ or Minarelli and the carb is a czech Jikov, which would point towards Eastern Europe .

[Peter1962]

I can't comment,as only posted what i had seen and what i thought was the Fishers intent, but with regards to design often similar solutions are arrived at because they represent the best solution anyway.
I just happened to have a word document open as i was looking for a quote from either Jan or Frits regarding Balance shafts. Then i noticed the one about the Honda, Yamaha,Bartol.
None of which I thought was derogatory, just a general observation.

With regards to balance shafts I am pretty Sure Both Frits and Jan favour them.
(Forgive me if I paraphrase from memory) The balancing of a crankshaft to whatever magic factor/figure with he counterweights, does not balance the engine. It only just moves the vibration it to someewhere else in the rev range less of a nusience or something like that. (remember Paraphrase from memory)
Pretty sure the reason a lot of Balance shafts may cost power (in some situations) is more to do with oil drag brought about by a poor choice of location (RSW125 this seems to be the case my own observation likely a Rotax carry over)

Frits 50cc design 'the balnce shaft high mounted with sealed bearings out of the way of oil(Maybe even under a vacum :rolleyes:)
My take is an engine construction is. if it is designed with a balance shaft, The engine design then can be made lighter (ie thinner wall thickness cases etc), also the balance shaft is also a potentially a convenient location to drive ancilleries such as water pumps. Maybe even a stator:shutup:

Personally i like the older style Husaberg balancer, that is almost disk valve like in appearance, Very clever and very original.
309410309411309412309413
Well first time i had seen it but it might be stream engine technology for all I know. Not that much is really new now.

I had a giggle the other day looking at a 1923 TT racebike (Works Douglas) Picture.
It had a very modern appearing front disk brake. With a caliper that was very much like a mornern cable operated Mountain bike caliper only finned.
309418309417


Husaberg, to which design of Frits are you referring ?

I like the husaberg balancer, it is a shame that KTM dropped it when they took over husaberg.

[husaberg]

Husaberg, to which design of Frits are you referring ?

I like the husaberg balancer, it is a shame that KTM dropped it when they took over husaberg.

Not sure what he calls it ? Frits?
He mentioned it earlier here on ese but I can't find the post. It was in relation to the use of sealed bearings.
The Balancer I thought was nifty, The Water pump in the head on the earlier models not so much........
From what I understand the bearings for the balancers have to be made now, as the size is unobtainable. (must have been a Honda idea)

[Muciek]

I don't know the engine but cylinder and head are clearly Rotax-inspired like 2T-I says. The cases look like CZ or Minarelli and the carb is a czech Jikov, which would point towards Eastern Europe .

Yes, engine is CZ typ. 516 converted to rotary valve and jikov carb.

[TZ350]

Had an interesting few evenings this week playing with a small bike on the dyno. The interesting bit was watching the exhaust pipe extending 10-15mm against the retaining springs as the rpm approached peak torque and the internal pipe pressure was at its maximum. Then as the internal pipe pressure dropped the springs would pull the pipe back in for a bit of over rev.

With two springs this effect could be made to happen in two stages. I even figured out a very easy way to adjust the spring tension on the fly to tailor when and how far the pipe would slid out and back.

After peak torque the pipe would pull back in as the rpm approached peak power. I can't help thinking this trombone effect could be made to be useful in some way.

With a fixed pipe the useable power spread looked to be about 4,500 rpm with a power curve that was flat for maybe 2,000rpm. I am not sure how much the sliding pipe could be made to extend that but when I get time it sure looks worth investigating it a bit more.

[Martin1981]

http://fs2.directupload.net/images/150227/temp/g2nyq3cw.jpg (http://www.directupload.net/file/d/3911/g2nyq3cw_jpg.htm)


No surprise that a 500ccm engine does not give more power than a 125ccm gp engine if the cylinder is mistreated like this. "The power valve ports are slightly smaller...." :brick: So why using a 500ccm engine if you don`t let it breathe? unbelievable...:sick:

[senso]

The man can know a lot and make a perfect hone with is eyes closed, but damn, its like killing cylinders, tiny ports :/

[husaberg]

[/URL]


No surprise that a 500ccm engine does not give more power than a 125ccm gp engine if the cylinder is mistreated like this. "The power valve ports are slightly smaller...." :brick: So why using a 500ccm engine if you don`t let it breathe? unbelievable...:sick:

It pays to consider that they also have a carb smaller than a 125 gp bike and were built to be ridden my lesser mortals on surfaces that offer less grip.

[Dutch Fisher]

My source:- Page 429


Originally Posted by wobbly
As we were talking about Yamaha and their lack of results here is an interesting story. Harold did the CNC anemometric flow testing on the BSL cylinder for me that I had lithographed in plastic. He showed me the dyno curves of his cylinder Vs Yamahas on the 125 when he was running their team with the Japanese rider Ui. Yamaha wouldn't let him use his 50.2 Hp set-up on the bike - even though their cylinder only managed 44.


Here is the preceding story, Wob, as told to me by my recently-passed friend Cees van Dongen. Cees was working on his son's Yahama TZ125 which was no match for the Honda RS125, power-wise. Cees changed the stroke from 50.7 to 54.5 mm and put a Honda cylinder on the Yamaha engine. Problem solved.
Bartol, facing the same problem while he was working for the Kurz Yamaha team, noted the dutch solution. Bartol also had a good connection with the factory and offered to develop a better cylinder for the TZ125. The Bartol cylinder turned out to be an exact copy of a Honda cylinder. Yamaha was not pleased...

[Martin1981]

It pays to consider that they also have a carb smaller than a 125 gp bike and were built to be ridden my lesser mortals on surfaces that offer less grip.

no question, husa, you are right. the 500ccm engines are discriminated where ever possible!

[wobbly]

Well of course Harold failed to mention to me that his Yamaha replacement cylinder was an exact Honda copy, and I had no reason to suspect it was
due to his access to the Czech machine.
Yamaha certainly didnt fall into the flattery by copy trap with the Y2K cylinder for the 250,as obviously Harolds influence was somewhat tarnished for them at that stage.
But if I over reacted to your sarcasm Mr Fisher, then I apologise unreservedly.
Try as I might though, I have never been able to get any idea what was inside a KTM, has anyone out there ever got any good pics.

[husaberg]

Yep, the concept of the system used by Team Roberts was admirable, but as Dave points out the dynamic squish in reality varies with rpm and I will add, bmep.
Making the head retract as the cylinder pressure increases against a set pressure above the insert is clever, but as is the usual case, no free lunch.
Squish clearance needs to vary with rpm ( and by default bmep ), so having the chamber fixed in space to the cover, and the squishband area moving independently
seems a really great lateral thought process that ticks all the boxes.
Minimising the end gas volume at all rpm, via a variable squish height, but having a fixed chamber would then give high com and high squish at low rpm ( bmep )
then translating into slightly lower com, along with low squish volume at high rpm ( bmep ).
Dropping the com as the engine comes onto the pipe, maximises the energy distribution as we know is actually needed, but at all times the squish volume is minimised - brilliant.
Having the close tolerances needed along with O ring seals wont affect the temp gradient we want ie a cold squish area, and a warmer chamber, if the thought process of the really effective squish cooling
scenario I have alluded to is used as well.
Hey, hey, maybe a small step for Dave, a giant step for 2T technology, good shit.

The system was the sort I posted earlier lol I had forgotten about that.....
http://www.kpmotosolutions.com/img041.jpg
Raineys Yzr is left

[RAW]

Well of course Harold failed to mention to me that his Yamaha replacement cylinder was an exact Honda copy, and I had no reason to suspect it was
due to his access to the Czech machine.
Yamaha certainly didnt fall into the flattery by copy trap with the Y2K cylinder for the 250,as obviously Harolds influence was somewhat tarnished for them at that stage.
But if I over reacted to your sarcasm Mr Fisher, then I apologise unreservedly.
Try as I might though, I have never been able to get any idea what was inside a KTM, has anyone out there ever got any good pics.

Follow the link Wob
http://www.pit-lane.biz/t118-gp125-caracteristiques-ktm-frr

Let us know your thoughts would you

[husaberg]

Follow the link Wob
http://www.pit-lane.biz/t118-gp125-caracteristiques-ktm-frr

Let us know your thoughts would you

For those who are not signed up to the pitlane forum.
http://www.kiwibiker.co.nz/forums/album.php?albumid=4857

[wobbly]

Well I do like the chamfer/flat top on the piston edge ( ha hah,I showed Harold that idea when I designed the BSL500, and it ended up in the Swiss Auto,Pulse, as well ) but it also appears to have a radius,that now, we have
VHM using to make better power from KZ2 engines.
But if Harold copied a certain Honda cylinder, then it for sure wasn't a late model A Kit as they ALL had very a oval Exhaust exit shape at the cylinder face that transitioned
into a round within the flange to mate with the header - no step = alot more power.
Honda even issued a tech bulletin that said you would loose alot of power if you ground the cylinder round to match the very old design spigot on the 125 customer bikes.
The best power I have ever got from a T port 125 cylinder was with a 41 wide by 32 high oval, and that was tested back to back starting at 40 round and progressively inserted/
welded and ground smaller and smaller in the cylinder and spigot.
The final design with the 41 by 32 dimensions used as cast in the cylinder - and CNC machined in the spigot made another Hp over my welded test pieces.
But shit Harold, every dumb arse could see that shaping the tang below the boost port was worth some power, allowing better flow from the reed cavity into the case area.
But no - so just maybe Mr Fishers sarcasm, and Frits tacit agreement are worth noting.

[husaberg]

This is the bulliten Wob is referring to.
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=240876&d=1308200871


as above found this on Honda rs125
Space bar now working again

[peewee]

honda used a oval for a brief time on their mx 250 cylinder. most guys had no clue why it was there and figured it must of been a manufacturing error and grinded it round :laugh:. yamaha still uses a oval style but i think they been using the same casting for nearly 10yrs or so.

[richban]

A question while there is talk on honda barrels.

In the pic below is a machined NSR150 sp barrel that is used to make up the NSR300 kit. I keep looking at the bridge between the ports and wondering it this should be cut lower. In the other pic is the view from inside the case's when I first started cleaning them up.

I suppose I am wondering if cutting this down (red line) and adding a radius instead of the sharp edge currently, would aid flow into both ports?

309463309464

[ken seeber]

Transfer passage entry obstruction

This is a picture of a TM KZ10B cylinder with the piston at BDC. The transfer cut out in the piston protrudes around 4.5 mm below the level of the side entry into the cylinder. Surely this must create a significant flow disturbance and loss of flow. Particularly so, as I am lead to believe, that the maximum mass flow rate occurs around BDC. In addition, it has been pointed out on how important it is to have a radius at the edge of the cylinder at this level.
309469

So, what are the options?

1. One could modify the piston a bit by blending, but there is a limit, particularly under the A ports, where only a mm or so of material removed will expose the aux exhausts to the crankcase at TDC. The picture shown this done a bit, but it is still far from perfect in terms of a relatively smooth junction
309468

2. Lower the level of the side entry into the cylinder so that it matches the level of the cut-out in the piston, ie adding a nominal 4.5 mm of material, effectively adding cylinder bore length at these points. Could look something like the yellow plasticine addition in this pic. Unfortunately I don’t have a set of crankcases to see if this could possible affect other aspects of the transfer flow entry into this area.
309466309467

3. Fit a longer rod in conjunction with a piston with a correspondingly lower compression height. Current engine has a 109.8 rod with a 29 compression height

4. Others ????


At the CIK/KZ level, it looks like 1. is the only option as the rules disallow any fundamental additions, visual and dimensional changes.

At the fresh or cleansheet design level though, I would think either option 2. or 3.

So, if you clever blokes had the choice, which one would you go for or is it just a non issue?

[richban]

Transfer passage entry obstruction

So, if you clever blokes had the choice, which one would you go for or is it just a non issue?

Now I am wondering how much air/fuel flow is actually happening at that moment of BDC?

[wobbly]

Killing two birds with one stoner is easy.
Forget the bridge Rich, its a fuckup, so get to work on the bore/duct interface.
Get a really big ballnose on there, copy Mr Thiels flow bench and championship winning methodology.
And as I have seen on a piston from a Euro Cup winning TecSav KZ10B the radius on the piston works as well - that guy doesn't grind Jack Shit for no reason.
The duct ballnose is worth at least an easy Hp in a 125, the piston mod is done by Savard for a reason, but I havnt quantified that yet, wont be long though - the Nationals are at Easter.
Makes it a bit harder when the KZ2 rules specifically forbid adding material, grinding the right bits is the black art.

BDC flow is where it all happens - the negative pressure ratio at the Ex port/cylinder junction is the deepest value and widest duration at this point, if the diffuser is designed correctly for peak depression
around BDC at peak Hp - as it should be.
Get the point - the port area is the greatest, the pressure ratio is the highest, what naturally follows is power making FLOW, and one of the biggest influences on FLOW into a duct is the entry geometry.

[richban]

Killing two birds with one stoner is easy.
Forget the bridge Rich, its a fuckup, so get to work on the bore/duct interface.
Get a really big ballnose on there, copy Mr Thiels flow bench and championship winning methodology.
And as I have seen on a piston from a Euro Cup winning TecSav KZ10B the radius on the piston works as well - that guy doesn't grind Jack Shit for no reason.
The duct ballnose is worth at least an easy Hp in a 125, the piston mod is done by Savard for a reason, but I havnt quantified that yet, wont be long though - the Nationals are at Easter.
Makes it a bit harder when the KZ2 rules specifically forbid adding material, grinding the right bits is the black art.

BDC flow is where it all happens - the negative pressure ratio at the Ex port/cylinder junction is the deepest value and widest duration at this point, if the diffuser is designed correctly for peak depression
around BDC at peak Hp - as it should be.
Get the point - the port area is the greatest, the pressure ratio is the highest, what naturally follows is power making FLOW, and one of the biggest influences on FLOW into a duct is the entry geometry.


Nice one. Thanks for that. When I pull the engine down and get stuck in I will post progress.

[Frits Overmars]

I keep looking at the bridge between the ports and wondering it this should be cut lower... I suppose I am wondering if cutting this down (red line) and adding a radius instead of the sharp edge currently, would aid flow into both ports?

309463309464It would certainly help the flow into the A-ports more than it would hurt the flow into the B-ports (if the latter would be hurt at all, which I can't tell).
So the bulk flow would improve. But sending more mass through the A-ports might upset the scavenging balance, so there are no guarantees here.

[Frits Overmars]

Transfer passage entry obstruction

This is a picture of a TM KZ10B cylinder with the piston at BDC. The transfer cut out in the piston protrudes around 4.5 mm below the level of the side entry into the cylinder. Surely this must create a significant flow disturbance and loss of flow.309469
1. One could modify the piston a bit by blending, but there is a limit, particularly under the A ports, where only a mm or so of material removed will expose the aux exhausts to the crankcase at TDC.
2. Lower the level of the side entry into the cylinder so that it matches the level of the cut-out in the piston, ie adding a nominal 4.5 mm of material,
3. Fit a longer rod in conjunction with a piston with a correspondingly lower compression height. Option 1 seems like a good bet.
Option 2: neaa... You should take Wobbly's advice instead.
Option 3: what would that change at the bottom of the cylinder?

[RomeuPT]

Well I do like the chamfer/flat top on the piston edge ( ha hah,I showed Harold that idea when I designed the BSL500, and it ended up in the Swiss Auto,Pulse, as well ) but it also appears to have a radius,that now, we have
VHM using to make better power from KZ2 engines.
But if Harold copied a certain Honda cylinder, then it for sure wasn't a late model A Kit as they ALL had very a oval Exhaust exit shape at the cylinder face that transitioned
into a round within the flange to mate with the header - no step = alot more power.
Honda even issued a tech bulletin that said you would loose alot of power if you ground the cylinder round to match the very old design spigot on the 125 customer bikes.
The best power I have ever got from a T port 125 cylinder was with a 41 wide by 32 high oval, and that was tested back to back starting at 40 round and progressively inserted/
welded and ground smaller and smaller in the cylinder and spigot.
The final design with the 41 by 32 dimensions used as cast in the cylinder - and CNC machined in the spigot made another Hp over my welded test pieces.
But shit Harold, every dumb arse could see that shaping the tang below the boost port was worth some power, allowing better flow from the reed cavity into the case area.
But no - so just maybe Mr Fishers sarcasm, and Frits tacit agreement are worth noting.

Hello. What you mean by "chamfer/flat top on the piston edge"? This kind of piston top: http://www.mitaka.co.uk/YAMAHA%20PISTONS/PT.05YZ125.htm ???

I seen somewhere that the chanfer on a flat piston improves power before peak? But the head must have this shape also for the result to happen. So, with this kind of flat top on the right head shape we will have more power everywhere compared to a domed top on a Honda Cylinder?!

Thanks

[ken seeber]

Option 3: what would that change at the bottom of the cylinder?

Frits,
By increasing the rod length and reducing the compression height of the piston, but leaving the crown at the same level relative to the cylinder (ie, its TDC and BDC positions would remain unchanged), the transfer cut out in the piston could be raised by the same amount, thereby better matching the cylinder. Should have explained this better. Another side benefit might be the less side thrust. A negative might be the fact that the piston pin and bearing might get hotter.

[Frits Overmars]

1. One could modify the piston a bit by blending, but there is a limit, particularly under the A ports, where only a mm or so of material removed will expose the aux exhausts to the crankcase at TDC.
By increasing the rod length and reducing the compression height of the piston, but leaving the crown at the same level relative to the cylinder (ie, its TDC and BDC positions would remain unchanged), the transfer cut out in the piston could be raised by the same amount, thereby better matching the cylinder.But the amount that the transfer cut-outs can be raised, will be limited according to your option 1 just the same. The minimum required piston length here depends on the distance from TDC to aux exhaust floor, irrespective of con rod length, doesn't it? I'm afraid I'm going to need a drawing to understand you on this.

[seattle smitty]

Hah, Ken, I have an old racing outboard with a waaayy uglier mismatch than that: 1977 Yamato RB-5 350cc flat-four piston-port. Pretty good bore/stroke (47.4X49.4) and long rods (because the engine was sleeved down from a 500cc), but the rest of it was pretty sad . . . partularly that mis-match. The piston skirt had to cover the piston-port, and the factory handled this by leaving half of the skirt hanging well over a centimeter into the path of the A/F charge that was supposed to flow into the single transfer port at BDC. I forget what Yamato was claiming for this 350, but somebody put a new one on the dyno and made about 58 hp . . . on methanol!!

Wobbly, evidently Ken knows what you mean, but I'm a little confused about the "ball-nose." Rotary-file? End-mill? In any case, the idea is to end up with a constant rolled edge, a smooth radius over the piston cut-out and the transfer entry, right?

I would think one possible step Ken could take in that direction is a longer rod, using the same piston and a spacer under the cylinder. Then he could make a good radiused entry . . . as well as probably having less unwanted shrouding of the transfers by the crankshaft wheels. There's a lot of that shrouding to be seen in my crappy old outboards.

(EDIT) Aw Dang, I didn't see that we'd got to P. 1128. Oh well.

[jonny quest]

what is the ideal BDC piston transfer case opening scenario? The big radius entries from cyl bore to transfer duct would seem to be counter intuitive if piston travels below this opening at BDC.

The KTM and RS have sharp cyl bore to transfer duct shape. would they improve with a big radius like the Aprilia?

[richban]

It would certainly help the flow into the A-ports more than it would hurt the flow into the B-ports (if the latter would be hurt at all, which I can't tell).
So the bulk flow would improve. But sending more mass through the A-ports might upset the scavenging balance, so there are no guarantees here.

Interesting. I went back through my photo's to try and find some early piston wash images. Would that give and indication of how the A and B ports are balanced? I'm sure I have a pic.

[husaberg]

Interesting. I went back through my photo's to try and find some early piston wash images. Would that give and indication of how the A and B ports are balanced? I'm sure I have a pic.

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=300568&d=1409608613
309472

[richban]

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=300568&d=1409608613
309472

Husaberg, keeper of the digital realm. Thanks for that. I am interested as to what the eyes of experience would read in it.

[jonny quest]

Problem with reading that piston is at one time, probably prior to that piston it was detonating. How much time is on that piston... because if you're not familiar with reading that type of fuel... it can be deceiving a bit. It doesn't look like that piston has more than two hours of run time... but transfer balance looks good.

[wobbly]

Yes, the YZ125 has a small chamfered edge on the piston, with a flat top - and this has been reported as being quite superior to a simple dome.
The KTM had a slightly wider chamfer,and some of the heads had a proper toroid, but in both cases the head shape follows the piston to get constant squish height.
In my original design the chamfer angle was the entire squish width, then a flat top, and this combined with a toroid chamber made better power than a dome
with a bathtub.
The ballnose shape on the transfer duct /bore wall entry was flow bench and dyno developed by Mr Thiel.
See pic.
The radius on the piston cutout has been around for years, and as Mr Savard at SavTec is doing this to his KZ10B engines, I will be trying it soon
when I test a batch of new lightweight piston designs, that also have thinner rings like an A Kit Honda ( more damn copying going on - its everywhere ).

[jonny quest]

I thought I read in the Pit Lane forum that Frits/Jan tried a radius on bottom of piston with worse results. I definitely could be mistaken. And if my memory is correct, did it not work because of the already rounded edge of cyl/transfer duct opening.

[richban]

Problem with reading that piston is at one time, probably prior to that piston it was detonating. How much time is on that piston... because if you're not familiar with reading that type of fuel... it can be deceiving a bit. It doesn't look like that piston has more than two hours of run time... but transfer balance looks good.

Can't remember the hours on that one but quite a few maybe 10hours. Yes big air leak got it rather cooked. It's still in the engine that has now done a full race season. Time to replace. Also we have never really looked at the piston at BDC in the barrel. I will be doing that today. Surely a Honda 250 bottom end with a 150 barrel a running a Kawasaki KR150 wiseco piston might be in need of some sort of match up. We will see.

[wobbly]

Rich, what is the deck height and ring pin position on the KR150 piston.

[Frits Overmars]

I am interested as to what the eyes of experience would read in it.

How much time is on that piston....

Can't remember the hours on that one but quite a fewWhich reminds me of the man who went to a fortune-teller to get some palm-reading done. The palmist promised him he would meet a gorgeous woman and get married. The man replied: "Some palmist you are. I got married to her allright. And divorced too!"
The palmist said: "What do you expect from me when you never wash your hands."
It's the same with spark plug and piston reading.

[kel]

I thought I read in the Pit Lane forum that Frits/Jan tried a radius on bottom of piston with worse results. I definitely could be mistaken.
You are not mistaken. It was mentioned in part two of the "all you need to know" thread

[richban]

Which reminds me of the man who went to a fortune-teller to get some palm-reading done. The palmist promised him he would meet a gorgeous woman and get married. The man replied: "Some palmist you are. I got married to her allright. And divorced too!" To which the palmist said: "Don't blame me if you never wash your hands."
It's the same with spark plug and piston reading.

Haha. Well I have been happily married to that little wiseco for over a year now. And when things are going great in your marriage, I figure its best to not to suggest she is looking old, caked in crap and needs a wash. She's getting ditched soon for a younger model.:rolleyes:

[190mech]

I too have wondered why the rounded(ballnosed)barrel to transfer duct,yet the sharp edged piston worked well with Mr.Thiels RSA engine.If the piston is held in the cylinder and slowly lowered.the transfer ports open well before the piston skirt interferes with the barrel/duct area.I tend to think the rounded area greatly improves flow during initial transfer opening and once its at BDC the duct volume is large enough to keep good flow..Just a theory from a country boy...

[richban]

OK so now not liking this piston as much.

Mock up at BDC. Or should I say cock up? Seams to be a lot of piston in the way. hummmm.


309486309487309489309488

[peewee]

OK so now not liking this piston as much.

Mock up at BDC. Or should I say cock up? Seams to be a lot of piston in the way. hummmm.


309486309487309489309488

do you see in the first pic how the wristpin hole pops open at bdc ? i wonder if thats bad. maybe frits or wobbly could answer. i have the same thing happen on one of my engines, some of my other engines the wristpin hole stays covered at bdc. depends on the cylinder wall length, wristpin height etc, i guess.

[richban]

do you see in the first pic how the wristpin hole pops open at bdc ?


Yeah its almost the same on the NSR250 barrel. But not as pronounced but you just see a touch of the wrist pin. But a 59mm piston stuck into cases that are made for a 54mm piston with no skirt mods is not looking that hot. Almost 6mm either side of the skirt needs to be chopped to bring it back to how a stock honda piston sits in the case. How much more could come off I don't know. But it looks like there can be big gains in the duct.

[husaberg]

Yeah its almost the same on the NSR250 barrel. But not as pronounced but you just see a touch of the wrist pin. But a 59mm piston stuck into cases that are made for a 54mm piston with no skirt mods is not looking that hot. Almost 6mm either side of the skirt needs to be chopped to bring it back to how a stock honda piston sits in the case. How much more could come off I don't know. But it looks like there can be big gains in the duct.

Rich was this a diy 300 or a Tyga300?


The cases were a bit of a mismatch to the transfer port entry and needed a bit of cutting. It was a toss up whether to cut the cases (for top end power) or to epoxy the cylinder (midrange). I went for the former. While I was in the cases, I smoothed out all the lumps and bumps for a smoother flow.
http://tyga-performance.com/site/index.php?cPath=73_191
I see prox do a kr150 piston.

[richban]

Rich was this a diy 300 or a Tyga300?


http://tyga-performance.com/site/index.php?cPath=73_191
I see prox do a kr150 piston.

Lets just say all Tyga kits are a little (Do it yourself). I should have noticed.

The photos are mocked up with stock cases. Mine are way way different, rough F3 case copy. But still the piston skirt is a bit of a wall. The good thing is it can be fixed. In an NSR250 at BDC the piston skirt sits above the tang the same amount as the 150 piston on the 300. But obviously it is a lot more narrow and scooped away more than the 150 piston.

[wobbly]

Yep Rich you are onto the issue.
I am building 3 - 300 engines right now using a 60mm Wossner piston based on RS125 with long rods from Samarin to correct two big issues.
The piston cutout being the obvious one you have found, and the second is that Tyga machine the 150 cylinder base to get the timing ( very ) roughly
in the ball park.
What it needs is a short deck piston, and a long rod ( as per A kit ) then a spacer plate to get the case volume increased to somewhere near correct, NOT
reduced by chomping down the deck.
This way you get to increase the case vol and fix the cutout issue, and get the boost port timing correct, so the A and B can be ground up, along with the Ex to correct the idiot
blowdown STA designed in by the Thai noddy in charge of the cylinder specs.

[richban]

Yep Rich you are onto the issue.
I am building 3 - 300 engines right now using a 60mm Wossner piston based on RS125 with long rods from Samarin to correct two big issues.
The piston cutout being the obvious one you have found, and the second is that Tyga machine the 150 cylinder base to get the timing ( very ) roughly
in the ball park.
What it needs is a short deck piston, and a long rod ( as per A kit ) then a spacer plate to get the case volume increased to somewhere near correct, NOT
reduced by chomping down the deck.
This way you get to increase the case vol and fix the cutout issue, and get the boost port timing correct, so the A and B can be ground up, along with the Ex to correct the idiot
blowdown STA designed in by the Thai noddy in charge of the cylinder specs.

3? You bastard. I hope they will not appear next to me on the grid anytime soon. In the MC21 chassis they are a fun fast bike.

[richban]

( as per A kit ) then a spacer plate to get the case volume increased to somewhere near correct

Just make sure you use them very very short plugs on the bottom barrel and watch you air gap in the forks. There is maybe 10mm to play with before you would be needing to loose front fork travel.

[wobbly]

You are lucky Rich, two are going to WA the other is here as road bike using a NSR250 frame, and will only get used for the occasional track day.
Dropping the plug into the head with the toroid will help, but yes there aint no room even with shorty RS125 plugs.
The one here is really being built to stick it up the Honda Fagots on the NSR forum, whos dying belief is that if HRC didnt build it then its a piece of shit.
So the sole idea is to blitz all their dyno numbers out of the park.

[richban]

You are lucky Rich, two are going to WA the other is here as road bike using a NSR250 frame, and will only get used for the occasional track day.

Good oh. Well there will be another 2 on the track by end of the year anyway. So spill the beans what does your sim file say the HP could be?

[wobbly]

The STA says 100 Hp crank = 88 rear wheel at 11500.
The limiting factor is keeping the powervalve/port geometry correct, so it cant be ground up much.
Sorry I should have said the one here is going into an RS250 chassis.
And now that we have gone long rod the cylinder does not need cutting and we dont need a plate, so plug/wheel clearance will be helped.

[richban]

The STA says 100 Hp crank = 88 rear wheel at 11500.
The limiting factor is keeping the powervalve/port geometry correct, so it cant be ground up much.
Sorry I should have said the one here is going into an RS250 chassis.
And now that we have gone long rod the cylinder does not need cutting and we dont need a plate, so plug/wheel clearance will be helped.

Nice one. Mine is 73 at the moment with stock barrels dyno jet 73 that is. 60hp at 8k so quite fat. It will be interesting to see what happens after chopping the piston skirt.

I am going to weld up an grind the power valves to try get a better fit / flow. They also have that hole in the middle. The F3 250 version does not. And I noticed the RS250 nx5 power valve is a seamless fit in the barrel. And the exhaust port roof is dead flat when they are fully open. Unlike the NSR.

[TZ350]

Whatt 1130 ....

Edgecumbe Bucket NI 2015 Round 3

309786

http://www.kiwibiker.co.nz/forums/showthread.php/153656-Chris-Bucket-photo-thread-Bandwidth-warning?p=1130840522#post1130840522

<iframe width="560" height="315" src="https://www.youtube.com/embed/AZ-FUJA3lbc" frameborder="0" allowfullscreen></iframe>

Team GPR Edgecumbe Videos:- http://www.kiwibiker.co.nz/forums/showthread.php/150352-Team-GPR/page125



... one remarkable issue, at least to me.... it seems that Jan realized just from the Beginning that the rotary inlet is the best for power. there are not many pictures showing Jan with piston port or reed valve engine. maybe a stupid question but is that the only reason (power) that he so to speak started straight off with the rotary inlet system or are there other reasons that makes him preferring it?
Jan should be answering this really, but I'll give it a try. I assume he started with a rotary because everybody in GPs was using that when Jan built his first engine.

For his own constructions he always stuck to rotaries, with one exception: the reed valve Rumi. It produced 46 hp on the test bench in a season where the world title was won with 42 hp, so our prospects were bright. Sadly this could not be said of management...

Jan made a direct comparison at Derbi where he developed the RSA while Lorenzo's GP-winning reed valve Derbi was still around. Jan worked on both engines, extracting 49 hp from the reed valver before dropping it in favour of the rotary RSA that produced 10% more power with the same cylinder.

The rotary engine has other advantages over the reed valver: setting the carburation is much less fussy. But the power difference is the main attraction.


Smitty,
Have been reading the latest round on cooling discussion, but with the mind focussing on more pressing matters, haven’t had the opportunity to comment of late.
My take on cooling a 2 stroke is that, as Frits says, you can never over cool a 2 stroke. This is a very general statement, generally applying to the overall engine. Cold air passing thru equals:
• Higher charge density – more power
• Cooler temps mean better lubrication control and durability(less oil breakdown/carburizing)
• Cooler temps mean less opportunity for detonation
You are fortunate with boats in that you have the world’s biggest radiator at your disposal, with typically a 15 – 20 deg C inlet flow temp, compared to bikes/karts where the ambient temp can vary from whatever in the northern hemisphere to over 40 in Oz. From this potentially high ambient temp we need to cool the coolant down to as low as possible maybe as a guess, even with a huge radiator, that this might have delta T of 10 deg over ambient. Passing through the engine, I seem to remember that a fairly normal increase was around 5 deg, this being obviously dependent on the flow rate. The higher the flow rate the better the actual heat transfer rate, giving a smaller overall temp differential across the engine. If the 5 deg is in fact the case in current racing 2 strokes (will bow to Frits and Wob on these matters), then the need for a separate circuit is hard to justify, but who knows…I don’t. The downside to higher flow rates is the power required to drive the pump and its heat input into the cooling system (previously discussed).
However what Wob is saying, I am sure, that overall cooling is good for all the obvious reasons, HOWEVER in certain areas there are specific needs for power and engine durability. Specifically:
• We want the spark plug to remain as cool as possible
• We want the two surfaces (head outer circumference and piston crown edge) that form the squish zone to be as cool as possible to avoid detonation
• We want the combustion zone to be as warm as possible tor maximum Carnot cycle efficiency, consistent of course with detonation and even pre-ignition control.
There have been some attempts at detonation control (other than the more subtle methods that are being currently employed), one of these being Warren Willing’s Yamaha sprung loaded cyl head combustion chamber that after a certain cylinder pressure was attained, the whole insert would shift outwards, allowing the pressure to drop. Dunno if it was ever successfully used though.
Back to combustion chambers. I think the ideal shape for a combustion shape is a sphere, which offers a minimum surface area to volume ratio, thereby minimizing heat transfer, allowing maximum combustion temps and efficiency. By employing squish zones, this allows a more compact combustion chamber shape. Not perfect, but clearly the way to go. And as Wob has been saying, the toroidal shape within the head is desirable as (I think) it places the spark plug gap towards the centre of the zone (obviously more so in the case of the flat top piston) so the flame kernel can radially progress. My understanding anyway.
If you want to see a shit combustion chamber, have a look at this: https://www.youtube.com/watch?v=0SiRqmo5Onc It can be clearly seen at the 3 minute stage.
In recognition of this, a direct fuel injection system was developed that, under the generic terminology of the day, DISC (direct injection stratified charge) which allowed the fuel (and a small quantity of injection air) to be injected late in) the compression cycle such that no fuel entered the acres of squish area. In that case, we were chasing fuel consumption and low unburnt HC emissions.
As a digression, this fuel injection system was very successful, particularly so when applied to a 2 stroke engine. (both crankcase or externally scavenged). The system is still being commercially manufactured today with applications such as marine (Mercury Optimax) to small drone engines (spark ignited running on jet fuel).
Personally I wish that some of the dumb arse controlling bodies, particularly in karting (which in my understanding is the largest (numerical) arena for competition 2 strokes) where they stick to archaic/ill considered rules (possibly for pecuniary reasons) and don’t allow any significant technical advancement opportunities, would use their imagination.
That’s what is great about this bucket thing. Lots of regulation freedom and cultural freedom, allowing guys like Neil and TZ350 and many others experiment, hopefully leading to the advancement of 2 strokes and their rightful and justifiable place in the future.
My thoughts anyway.



Seems that we've been pumping the coolant the wrong direction, all these years. Wouldn't it be better to have the biggest temperature delta in the head instead of the cylinder?There are two issues in the cylinder that need the most attention from the coolest water available.

Over the transfer duct outer walls, and the Ex duct outer walls.

The first as this keeps the inducted charge as cool as possible, the second is to keep the trapped slug of fresh ( ish ) fuel air in the Ex duct also as cool as possible.

The slug gets stuffed back past the closing piston ,thus this contributes to the combustion process - and if overheated it creates deto very quickly.

Wrap your header with glass insulation tape - and quickly find out what not to be doing.
We have a trade off situation in the cylinder/head interface.

As Frits alludes to we don't want a "hot " head contributing heat to the cool charge being compressed prior to ignition, but on the other side of this coin we dont want
cold alloy pulling heat out of the ignited mixture.

As DEA etal have found the tradeoff currently works in the favour of the carpet bombing approach of cooling the hell out of everything in the head.

But as I have found dozens of times if you ceramic coat the chamber only, power goes up.
When you ceramic coat, two things happen.The coolant temp drops, always a good thing, and this cooler water in the head then possibly has a chance to do more good by dropping the end gas temps, thus helping to keep deto at bay.

Jan found a very simple way of keeping the plug cool, you guys wanting to tune to the edge of available power need to think of your own solution to effectively cooling the squishband, in a better way than the current carpet bomb approach.






The Aprilia setup with 0.7 squish I believe would just clip at the absolute overev margin of 14500

Now I have the squish cooling organised in KZ2 I can run down at 0.9 ( from 1.3 min ) and it just clips at 15200.
The 66 bore Banshee/RZ based race engine with 58 stroke set at 1mm will clip at 12200.

A TM125 MX engine for open karts would clip at 13200 with 0.6mm A CR250 road racer set at 0.9 will clip at 11400.
That gives you some idea of the state of play from real experience.

The big open class Jetski World Champ engines I used to build needed an absolute minimum of .15mm = 0.006" clearance
on 78 to 92 bore when running 40*C out of the case and 60*C out of the head.

On the dyno the power would fade at the end of a 30 second pull if the case went over 40* - much under that and we would certainly squeek a piston. We used restrictor jets on the individual 6 outlet points to regulate the local temps.
Wobbly did you make an error and put the decimil place in the wrong spot there
is this supposed to read 1.5 mm

Was this a 951 seadoo with a huge piston
Nope - 6 thou is the correct number and yes a 951 out to near 1200.


wow thats tight squish. Am i reading it wrong is that measured at a certain rpm or a static measurement

Yeah I have been around the big bore 951 a little as well not at the same level as you i never took one to the world titles. They make good power until they don't and then you throw it all in the bin
I think he's talking piston to bore clearance .... were those forged pistons, did you have a shrinkage problem ? Or set them up tightish and run through several heat cycles ?
Yes, I was referring to bore clearance needed when using the cold water from the tap - or Lake Havasu in this case.

Smitty was talking about the loose clearances they have to run when going WOT with cold water in boat racing.
The only issue was simply that the low inlet temp along with an iron sleeve meant the piston would always be growing far faster than the bore size.

In the smaller bores there were cast pistons available and after long run in cycles these would survive at 0.004".
But the big bores were forged by Mahle, and nothing I did regarding slow run in, and sanding off the high spots etc would stop them locking up if under 0.006".

Of course this let the piston rock all over the shop, and the rings had a real hard time sealing effectively for long, but was the only way to get over 220 Hp from the big twin for open class racing against 1200 triples that had more power but were way heavier than the SeaDoo with titanium/magnesium everything, and a carbon hull.



I'm elderly and on slow dialup, i doubt I'd live long enough to print out the entire thread....And just picking Wob's posts, it doesn't as far as i can see anyway, give the full reply/post just the first couple of lines. Context is important too, someone should spend a week or so sorting the questions and answers...You've created a monster. you don't print it you save it, (took less than 30 seconds for me on a set up worse than 50 per cent of nz has)then you put it in word use an advanced find, to search the key words for which ever topic you wish to separate out.
Then you sift through. Sort the wheat from the chaff.
If it was to be done it would need some sort of frame work to start from.
Say a previous book.



... some "average" minarelli am6 kit's come with good porting from stock (kit's with 70, 75, 80cc), but have a exit diameter of 28mm (and the initial header of the pipe should enter this 28 diameter), calculating a pipe says it should have 30 ou 31 header. Then I did the same for some pipes, after the piece that fits in the cylinder I put a first cone of 20 or 25 length putting the diameter where it belongs. Same goes for even bigger kits with 32 round.


All the kits I have looked at for 50cc have way too big Ex ducts.
Take AM6 Hebo 192 Ex for example.
The port effective area is 24.2 dia, the Ex exit is 25, it should be 22.2 dia, and the best scenario is the exit should be oval at 24 wide and the header match that.
The step top and bottom does "work", but an oval to round transition is much better.
You can do this as the first cone of the header, but is way better if its done as part of the slip joint spigot.
Stage 6 and the Athena 50cc kits are no better in this regard.
All you have to do is work out the T port or 3 port effective area diameter, and that is the header entry size.
The duct exit should be around 75% area - all this is done for you in EngMod code - easy.
Counterboring the Ex duct exit as far as you can and then pressing in a sleeve to make the correct oval shape is also easy enough if you cant or dont want to get a tig torch in there.


A question. I thought of the other day is a Main port with Aux Ports has effectively 2 bridges.
Yet it is said to produce more power than a bridged Tee port.
I always thought (irespective of any main bridge bulging issues) it was down to a interupting effect of the bridge.
But.............


More blowdown area in a 3 port.More of the exhaust area is concentrated higher in it despite the shape of the T port.


Several reasons for the 3 port being superior.
To gain the maximum blowdown the T port needs two things.
A straight top timing edge, and the outer corner rads ro be as big as possible above the A port.
These two requirements both have big downsides.

The first is that the flat top edge has a very big duct length delta between the corner at the T and the corner at the outer edge.
This smears the outgoing pressure front, reducing its peak amplitude, thus scavenging energy.
I tried helping this in a test where the outer, longer length corner was higher than that at the T - sorry no free lunch, no more power.

The second means that the T port side edge is wrapped around very close to the A ports front and top edges, thus dramatically increasing the possible short circuiting of the
flow out of the A port.

And yes the 3 ports stepped opening does create a stronger more coherent exit pulse, and at 98% width and even with big angled pockets at the outer corner exits into the duct, the Cd value
of the T is always compromised in relation to a 68 to 70% width 3 port setup, with lower Aux around to bore centre.

[husaberg]

Nice one. Mine is 73 at the moment with stock barrels dyno jet 73 that is. 60hp at 8k so quite fat. It will be interesting to see what happens after chopping the piston skirt.

I am going to weld up an grind the power valves to try get a better fit / flow. They also have that hole in the middle. The F3 250 version does not. And I noticed the RS250 nx5 power valve is a seamless fit in the barrel. And the exhaust port roof is dead flat when they are fully open. Unlike the NSR.

I could be wrong, but i think the RS has a longer valve from its pivot point so actually has better geometry.

[richban]

I could be wrong, but i think the RS has a longer valve from its pivot point so actually has better geometry.

Yep thats right. I think with some careful welding and shaping the NSR one can be improved.

[rodg]

Had an interesting few evenings this week playing with a small bike on the dyno. The interesting bit was watching the exhaust pipe extending 10-15mm against the retaining springs as the rpm approached peak torque and the internal pipe pressure was at its maximum. Then as the internal pipe pressure dropped the springs would pull the pipe back in for a bit of over rev.

With two springs this effect could be made to happen in two stages. I even figured out a very easy way to adjust the spring tension on the fly to tailor when and how far the pipe would slid out and back.

After peak torque the pipe would pull back in as the rpm approached peak power. I can't help thinking this trombone effect could be made to be useful in some way.

With a fixed pipe the useable power spread looked to be about 4,500 rpm with a power curve that was flat for maybe 2,000rpm. I am not sure how much the sliding pipe could be made to extend that but when I get time it sure looks worth investigating it a bit more.


Thanks to the efforts of these chaps we doubled the horsepower on my TZ80! We ended up running no spacer in the pipe but the trombone movement in the pipe TZ350 refers to is still doing whatever it does!. Before tuning and after tuning graph attached. Biggest problem initially was a badly mis-matched pipe. TZ350 has kindly lent me an RG50 pipe based on a 10 year old wobbly design. After too many runs and optimising ignition and jetting for each run the bike now pulls from 9000 - 15000RPM on the dyno and consistently makes 20HP. Funnily enough it doesn't feel this broad on the track - it doesn't bog but lift off happens around 11000 and carries through to 14500. By drilling the air correction jet from 0.8mm to 1.25mm and jetting up accordingly (Keihin 138 to 150) we were able to improve the over-rev significantly

Raced the bike on the weekend and it lasted the weekend and I had my best ever result in the last and longest race of the weekend. First two stroke (thanks to mechanicals on some of the other two strokes). Only change from dyno tune was raising the needle. Water-temp got to 87 degrees C so sorting cooling is the next trick. Bugger all room for a bigger radiator so may install a second smaller one out of the way.

Also not sure my PVL analog kart ignition is the best tool for the job. Doesn't retard until really high RPM leaving ignition too advanced in low and medium RPM.

Thanks again to the generosity of skills, time and gear to the chaps at the House of Speed

[wobbly]

The PVL kart ignitions come in all manner of flavours but the most common are the ones used on the 125 shifters.
If the stator winding resistance is around 50 ohms ( 1850 turns ) then the "curve " is basically a straight line ie no retard.
As the stator winding resistance increases, the line is still pretty much straight, but drops at a set rate /1000 rpm.
The 200 ohm stator ( 4000 turns ) retards about 8* from 2000 to 12,000, the retard characteristic is set by the inductive reactance of the stator winding coil number
that is directly related to the static measured resistance.
There is a stator winding that has cotton/epoxy covering the wire, this has the max number of turns that will fit on the bobin ( so the plastic moulded cover wont fit.
It has 5000 turns and it retards about 11* from 2000 to 12,000.
This was developed for the Banshee that has limited kick start travel, so needed the extra coil turns to get it to start.
I got PVL to make these and it puts out just enough spark at kickover to start the quad, and as a side benefit, gave the max retard available from an analogue.
They could do more turns, but the spark voltage at high rpm would kill the 458 ignition coil.

[TZ350]

Thanks for your explanation Wob.

309598

At first I had trouble getting my head around their graphs, they did not make sense until I realized that the "0" line represents the static timing point which could be any number of degrees one chooses BTDC and their curve moves + and - relative to that point.

309597
As I now understand it, in this graph, if the initial timing was set at 15 deg BTDC then "0" on the graph means 15 deg BTDC and at 2000 rpm the real ignition point is 15 + 3 = 18 deg BTDC, at 8,750 rpm it is 15 + 0 = 15 deg BTDC and at 12,000 rpm it means 15 - 3.5 = 11.5 deg BTDC.

Also things can get confused when using a timing light because the trigger circuit in the timing light has some capacitance and therefor some delay in flashing the light after the triggering event. This has the effect of the timing appearing to be more retarded than it really is. At low rpm when there is plenty of time this error is very small and not much of a problem but at 9 - 10,000 it can get very noticeable and at 12 -14,000 significant.

Exaggerated retard due to the timing light flashing late, is just another thing to watch out for.

[husaberg]

The PVL kart ignitions come in all manner of flavours but the most common are the ones used on the 125 shifters.
If the stator winding resistance is around 50 ohms ( 1850 turns ) then the "curve " is basically a straight line ie no retard.
As the stator winding resistance increases, the line is still pretty much straight, but drops at a set rate /1000 rpm.
The 200 ohm stator ( 4000 turns ) retards about 8* from 2000 to 12,000, the retard characteristic is set by the inductive reactance of the stator winding coil number
that is directly related to the static measured resistance.
There is a stator winding that has cotton/epoxy covering the wire, this has the max number of turns that will fit on the bobin ( so the plastic moulded cover wont fit.
It has 5000 turns and it retards about 11* from 2000 to 12,000.
This was developed for the Banshee that has limited kick start travel, so needed the extra coil turns to get it to start.
I got PVL to make these and it puts out just enough spark at kickover to start the quad, and as a side benefit, gave the max retard available from an analogue.
They could do more turns, but the spark voltage at high rpm would kill the 458 ignition coil.
thanks Wob too for that explanation.
So why could did they not try to achieve that same result with a simple delay/resistance circuit in the ignition module? isn't that how the Japanese tended to do it? pre digital.
What am I missing.........likely something obvious....
http://www.kiwibiker.co.nz/forums/showthread.php/142498-MB100-development?p=1130181478#post1130181478
last and first attachment.

[TZ350]

So why could did they not try to achieve that same result with a simple delay/resistance circuit in the ignition module?
What am I missing.........likely something obvious....

My pick is simplicity, inductance of the stater does not change with age or heat like a separate RC circuit with discrete components could.

[RAW]

309599309600
A couple of pictures for you all

[seattle smitty]

Does every bike racer in New Zealand have his own dyno??? Honestly, going by the posts on this thread it would seem you Kiwis have at least five times as many dynos per capita as anyplace other than possibly Holland!!

Which company's dynos are favored here, or do y'all build your own?

[richban]

Does every bike racer in New Zealand have his own dyno??? Honestly, going by the posts on this thread it would seem you Kiwis have at least five times as many dynos per capita as anyplace other than possibly Holland!!

Which company's dynos are favored here, or do y'all build your own?

From what I can tell. The old Dyno Jet inertia dyno's seem to put out a number that is globally comparable. But yes I have had my bike on 2 different home built versions, different numbers but repeatable in there own right. If I wanted to get more power I could put the bike on a Dyno Dynamics setup. Usually 10 to 12% up on the dyno jet. One day I will have my own in a shed. One day!

[rodg]

The PVL kart ignitions come in all manner of flavours but the most common are the ones used on the 125 shifters.
If the stator winding resistance is around 50 ohms ( 1850 turns ) then the "curve " is basically a straight line ie no retard.
As the stator winding resistance increases, the line is still pretty much straight, but drops at a set rate /1000 rpm.
The 200 ohm stator ( 4000 turns ) retards about 8* from 2000 to 12,000, the retard characteristic is set by the inductive reactance of the stator winding coil number
that is directly related to the static measured resistance.
There is a stator winding that has cotton/epoxy covering the wire, this has the max number of turns that will fit on the bobin ( so the plastic moulded cover wont fit.
It has 5000 turns and it retards about 11* from 2000 to 12,000.
This was developed for the Banshee that has limited kick start travel, so needed the extra coil turns to get it to start.
I got PVL to make these and it puts out just enough spark at kickover to start the quad, and as a side benefit, gave the max retard available from an analogue.
They could do more turns, but the spark voltage at high rpm would kill the 458 ignition coil.

Thanks Wobbly. I have the 200 ohm stator

See attached photos of the result of the weekend's racing. Am thinking last 30 lap race finished in the nick-of-time! Pooh about crack in skirt of barrel.

309607309608309609309610

[chrisc]

See attached photos of the result of the weekend's racing. Am thinking last 30 lap race finished in the nick-of-time! Pooh about crack in skirt of barrel.

Oh shit! That could have ended really poorly Rod. I take it you'll just buy a new barrel there?

[rodg]

Oh shit! That could have ended really poorly Rod. I take it you'll just buy a new barrel there?

you bet! Lucky I didn't enter development class at the Nationals

[TZ350]

Thanks Wobbly. I have the 200 ohm stator


309618

A photo of rodg's tacho towards the end of a dyno pull, 15,500 rpm.

rodg reports that usable power was from 9,000 to 14,500 rpm, by my count that is a 5,500 rpm power spread, so who was it, who said that the 85's would be peaky.

[TZ350]

309620309621

Bit of precision work by Chambers on the RG50's, and, yep that is a NOS cylinder that has never been run.

309622

A loncin after market CDI stator converted to a 12V DC generator for the Ignitec

http://www.aliexpress.com/item/Performance-Racing-Magneto-Stator-Rotor-Kit-Dirt-Bike-LF-for-Lifan-140-150cc-CDI/1731580291.html

309623

Plenty of unmasking possible here.

309624309619

Some more cut and shut required to get the tips of my reed cage closer to the inlet and boost ports.

Reed cage and manifold came from Treatland, great guys to deal with:- http://www.treatland.tv/OKO-26mm-reed-block-intake-for-DIO-BLK-BLK-p/oko-dio-reed-block-105.htm

[husaberg]

309622

A loncin after market CDI stator converted to a 12V DC generator for the Ignitec

http://www.aliexpress.com/item/Performance-Racing-Magneto-Stator-Rotor-Kit-Dirt-Bike-LF-for-Lifan-140-150cc-CDI/1731580291.html


I am posting far to much and doing far to little but I found these as the CR125 ones will get harder to find.
Ktm125-300 seem to have a nice small rotor stator Kokistan with 25 watts or 50 watts aftermarket
http://www.cafehusky.com/threads/08-cr125-with-ktm-125-lighting-stator-howd-ya-do-that.2755/
309628309629309630

http://www.thumpertalk.com/topic/930729-ktm-200-flywheels/
http://www.rmstator.com/en_ww/products/rm01374-high-output-stator-ktm-1998-2011-exc-mxc-sx-sxs-xc-xc-w?___from_store=en_ww
http://www.ebay.com/itm/NEW-KTM-125-EXC-MXC-SX-SXS-50W-LIGHTING-STATOR-MAGNETO-SOURCE-COIL-/221120717793
pretty sure it might be very similar to the Honda cr one
Plus I also found these.

Its an outer rotor from HPI
http://www.hpi.be/210.php
http://www.hpi.be/item.php?item=210K008
https://www.treatland.tv/PUCH-HPI-CDI-mini-rotor-ignition-system-24K-gold-p/puch-hpi-cdi-90-gold-used-2.htm
309625309627309626

[Muciek]

Look for ones from Chinese 2T& 4T scooters (magneto and stator cost 15$ in motor store here) they are cheap as chips, they have 6 to 8 coils so around 70-100W. Outside diameter around 100mm

[F5 Dave]

Rob don't make my mistake and get greedy hacking the skirt for inlet space.

[wobbly]

You cant use the old CDI cheater trick with a PVL.
It uses the same coil to charge the capacitor on the N pole magnet ,then triggers the output circuit with the S pole using that same coil.
In the usual systems of old there was a charge coil, and a separate trigger .
If you simply put a small value capacitor across the trigger this would completely change its inductive reactance curve.
In old TZ350s we could set the static at say 4mm, and the cheater trigger mod would pull it back to 1.5mm at 10,000.
The same idea can be used to cheat the ignition timing in some kart classes but I know nothing about any of that.

[190mech]

Wobbly,Could you give us some more details on the small capacitor installation for altering the ignition curve?Although I know you would never do this in the restrictive kart classes,possibly some scooter tuners could put it to good use!
Thank You!

[koba]

A loncin after market CDI stator converted to a 12V DC generator for the Ignitec


Watch out for these, my one failed, that was my issue at Taumaranui, the rotor was moving in relation to the taper.
The taper wasn't slipping, nor were the rivets but it broke between the taper and the part that rivets to the rotor in such a way that it appeared normal until under heavy load, then it would move.

I'm considering a 12v scooter one as I also want to build an engine that can run lights and indicators for my dirtbike.
Or I could go to CR250 or something.
The budget did just get killed though, it will have to wait a while.

Any tips?

[cotswold]

Thanks Wobbly. I have the 200 ohm stator

See attached photos of the result of the weekend's racing. Am thinking last 30 lap race finished in the nick-of-time! Pooh about crack in skirt of barrel.

309607309608309609309610

Rod, chuck your 50 cylinder back on and do the F5 GP instead

[F5 Dave]

Rod, chuck your 50 cylinder back on and do the F5 GP instead

A fine idea. A worthy idea.

[F5 Dave]

Watch out for these, my one failed, that was my issue at Taumaranui, the rotor was moving in relation to the taper.
The taper wasn't slipping, nor were the rivets but it broke between the taper and the part that rivets to the rotor in such a way that it appeared normal until under heavy load, then it would move.

I'm considering a 12v scooter one as I also want to build an engine that can run lights and indicators for my dirtbike.
Or I could go to CR250 or something.
The budget did just get killed though, it will have to wait a while.

Any tips?


Koba, chuck your 50 cylinder back on and do the F5 GP instead
Just pre-empting what Cots will say next.

[cotswold]

Just pre-empting what Cots will say next.

Already told Kobe to get that done, I ( hope ) believe it was the sole reason he bought it, plus I beat him in the last F5 GP so he needs redemption. :laugh:

[wobbly]

Adding a 0.47mfd/200V cap across the trigger will create around 1*/1000 rpm retard.
So with around 6mm static I think it stared at 35* and by 10,000 it had 1.6mm = about 17*from memory
Thus the old pretty much straight line became a crude retarding unit, with extra mid advance for drive, and extra retard over the pipe for overev.

[husaberg]

Wobbly,Could you give us some more details on the small capacitor installation for altering the ignition curve?Although I know you would never do this in the restrictive kart classes,possibly some scooter tuners could put it to good use!
Thank You!
He used to do a roaring trade in them
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=249252&d=1319412316
http://www.bdkraceeng.co.uk/Bike5.html
http://www.bdkraceeng.co.uk/Bike2.html


last paragraph first page below. keep clicking on it till it is large enough to read
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=249261&d=1319423423
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=249262&d=1319423495


I can't remember what the variable capacitors are called but they used to be in radios.....
309650


The Ignitech is the obvious top self bees knees set up, but it may be possible to provide a lower tech solution.
I seem to remember JayCar having a adjustable delay circuit.
http://http://www.jaycar.com.au/images_uploaded/LM555.PDF (http://www.jaycar.com.au/images_uploaded/LM555.PDF)
http://http://www.ehow.com/how_4827785_build-time-delay-circuit.html (http://www.ehow.com/how_4827785_build-time-delay-circuit.html)


555's are useful little beasts........But to map them would take a set up like wobs...
Post it again Wob
oh I found it once I figured out how to spell vacuum


The 5K plug with no cap resistance and Magnecor 10mm wire works a treat with no RF problems for the Ignitech.
I use Ditex ignition test gear into my laptop.
Here is a video of the twinfire with Crane PS92N enormous cdi coil, on my test rig with CR125 stator/rotor/reg/cap.
http://www.youtube.com/watch?v=pA6kjjEMiaw&feature=plcp


Its a vacuum cleaner motor with a light dimmer rheostat and reverse switch for speed and direction.
Small toothed belt drive so I can use a big degree wheel on one end of the shaft and the ignition on the other to check timing curves..
Shaft slides in and out on eccentric lock bearings to position the rotor correctly.
I have seen nicer rigs using spindle moulder motors, but the old Hoover motors are free.


Here is a pic of cranks for Aprilia 250.
Full circle, full width, plenty of Mallory, high inertia, very low in cycle speed variation, lots of power and overev - why isnt your crank like this??
Also pic of my Ignition rig.
A vacuum cleaner motor with light rheostat, also reversable, has protractor on the other end.
I use a cheap kart rev counter and a strobe.
Doing curves on anything is easy, once its set up.
309651

https://www.youtube.com/watch?v=pA6kjjEMiaw

[koba]

Already told Kobe to get that done, I ( hope ) believe it was the sole reason he bought it, plus I beat him in the last F5 GP so he needs redemption. :laugh:

You are wrong, you said 'instead' rather than 'as well'.

[TZ350]

Racing at Edgecom http://www.kiwibiker.co.nz/forums/showthread.php/150352-Team-GPR?p=1130838589#top

[rodg]

Rod, chuck your 50 cylinder back on and do the F5 GP instead

would be keen but out of country watching NZ win cricket world cup final

[RomeuPT]

Hello.

Wobbly, if you can give a little help on pipes. Thanks
In normal round exit cylinder's a small step (diff diameters) from cylinder exit to exhaust header is good, ok! For example the cylinder exit's at 32mm and the header begins with 34. Seems to work fine.
But say we got a 30 exit round and the calculation of header inicial ideal diameter is about 34, wouldn't it go better with a first small taper cone from 30 to 34? Similiar purpose of an oval to round transition from 37 to 41? I have been doing this, but not sure if it's effect is real.

For example, some "average" minarelli am6 kit's come with good porting from stock (kit's with 70, 75, 80cc), but have a exit diameter of 28mm (and the inicial header of the pipe should enter this 28 diameter), calculating a pipe says it should have 30 ou 31 header. Then I did the same for some pipes, after the piece that fits in the cylinder I put a first cone of 20 or 25 lenght putting the diameter where it belongs. Same goes for even bigger kits with 32 round.

Wrong or right thing to do?

Thanks

[dark art]

The smoother the pipe (from exhaust port) is, the bigger the hp potential. But not everybody look for max hp all the times.
There are several cases where we want a mismatched pipe, most mx bikes have a considerable step, even smaller cc bikes, not only 250´s.

I´ve been able to extract more power out of a particular engine with a lower ressonant pipe, just like Wobbly described a few pages back, than with a full ressonant pipe. The engine turned more rpm and thus, made more power. With a full ressonant pipe, the electrics and carburation were not able to cope with large torque variations.

[wobbly]

All the kits I have looked at for 50cc have way too big Ex ducts.
Take AM6 Hebo 192 Ex for example.
The port effective area is 24.2 dia, the Ex exit is 25, it should be 22.2 dia, and the best scenario is the exit should be oval at 24 wide and the header match that.
The step top and bottom does "work", but an oval to round transition is much better.
You can do this as the first cone of the header, but is way better if its done as part of the slip joint spigot.
Stage 6 and the Athena 50cc kits are no better in this regard.
All you have to do is work out the T port or 3 port effective area diameter, and that is the header entry size.
The duct exit should be around 75% area - all this is done for you in EngMod code - easy.
Counterboring the Ex duct exit as far as you can and then pressing in a sleeve to make the correct oval shape is also easy enough if you cant or dont want to get a tig torch in there.

[husaberg]

All you have to do is work out the T port or 3 port effective area diameter, and that is the header entry size.
The duct exit should be around 75% area - all this is done for you in EngMod code - easy.
Counterboring the Ex duct exit as far as you can and then pressing in a sleeve to make the correct oval shape is also easy enough if you cant or dont want to get a tig torch in there.

A question. I thought of the other day is a Main port with Aux Ports has effectively 2 bridges.
Yet it is said to produce more power than a bridged Tee port.
I always thought (irespective of any main bridge bulging issues) it was down to a interupting effect of the bridge.
But.............

[adegnes]

A question i thought of the other day is a Main port with Aux Ports has effectively 2 bridges
Yet it is said to produce more power than a bridged Tee.
I always thought (irespective of any main bridge bulging issues) it was down to a interupting effect of the bridge.
But.............

Could it have something to do with the position of the bridge(s)?

[136kg136ps]

More blowdown area in a 3 port.More of the exhaust area is concentrated higher in it despite the shape of the T port.

[senso]

In some cylinders you can also make big T shaped ports above the transfers, but the duct shape will be sub optimal and hinder/limit gas flow.

[adegnes]

More blowdown area in a 3 port.More of the exhaust area is concentrated higher in it despite the shape of the T port.

But what if you made the T-port exactly the same shape as the 3-port, only difference being the central bridge vs one on each side. The T would undoubtedly have more blowdown area.

[RomeuPT]

Could it have something to do with the position of the bridge(s)?

It has to do with pulse dinamics created by the pipe. Single port opens first then the auxialiary, making the pulse going more "coerent" when the port opens than divided with the T port. The stronger the pulse the better exhaust action..

I am right? :tugger:

[wobbly]

Several reasons for the 3 port being superior.
To gain the maximum blowdown the T port needs two things.
A straight top timing edge, and the outer corner rads ro be as big as possible above the A port.
These two requirements both have big downsides.

The first is that the flat top edge has a very big duct length delta between the corner at the T and the corner at the outer edge.
This smears the outgoing pressure front, reducing its peak amplitude, thus scavenging energy.
I tried helping this in a test where the outer, longer length corner was higher than that at the T - sorry no free lunch, no more power.

The second means that the T port side edge is wrapped around very close to the A ports front and top edges, thus dramatically increasing the possible short circuiting of the
flow out of the A port.

And yes the 3 ports stepped opening does create a stronger more coherent exit pulse, and at 98% width and even with big angled pockets at the outer corner exits into the duct, the Cd value
of the T is always compromised in relation to a 68 to 70% width 3 port setup, with lower Aux around to bore centre.

[136kg136ps]

I haven't modeled them side by side but using Frits suggestion to graph each degree of exhaust one could easily see if it is possible to get equivalent blow down area.Maybe is the gas dynamics of staggering the separate openings but it doesn't look easy to get equivalent exhaust timing,blow down area and exhaust area.Hopefully on of our esteemed sages will clarify.My expertise is big engines with moving parts that go roundy round not up and down.

[richban]

I am thinking of trying out some 40mm lectron's on my 300. Wob I noticed in your 300 spec the carb recommendation was 39mm. What carbs were you thinking of using. I have never had a really close look at the lectron let alone tried tuning one.

[Bert]

I am thinking of trying out some 40mm lectron's on my 300. Wob I noticed in your 300 spec the carb recommendation was 39mm. What carbs were you thinking of using. I have never had a really close look at the lectron let alone tried tuning one.

Why???
We haven't even got to the stage of using the TPS and powerjet... I would have thought there was still a lot of love to be gained yet.:wacko:

[richban]

Why???
We haven't even got to the stage of using the TPS and powerjet... I would have thought there was still a lot of love to be gained yet.:wacko:

Yep. But to be honest I want the best simple option. I want the best carb for the job. The one that flows best and is most tuneable. Less dyno more racing.

[wobbly]

The Lectron 40HV flows alot more air than a 38mm SPJ but has a venturi behind the slide of 36mm.
Thus at part throttle it acts like the smaller carb.
Insanely easy to jet.
Just get a pair of 5-2 and 4-2 needles, then fine tune the high range with 40 to 70 powerjets - also makes equalising & fine tuning each side simple as well.
The TZ400 when it ran at PI had 4-2 with 85/90 on top, so I will now go to 5-2 and drop down to around 50 powerjets.
And when you want to go sex plus I have made some inline solenoid bodies that will switch the PJs from Ignitech.

[richban]

The Lectron 40HV flows alot more air than a 38mm SPJ but has a venturi behind the slide of 36mm.
Thus at part throttle it acts like the smaller carb.
Insanely easy to jet.
Just get a pair of 5-2 and 4-2 needles, then fine tune the high range with 40 to 70 powerjets - also makes equalising & fine tuning each side simple as well.
The TZ400 when it ran at PI had 4-2 with 85/90 on top, so I will now go to 5-2 and drop down to around 50 powerjets.
And when you want to go sex plus I have made some inline solenoid bodies that will switch the PJs from Ignitech.

Cheers. So what is the off throttle fuel feed like? I sort of like having the rich pilot when the brakes are on into a corner.

[F5 Dave]

So going off APT? I'd have bought one for my GG if I'd had the spare. Dumb single income. Wife lost her part time job today.

[wobbly]

Rich wants simple - APTs need alot of dicking around to get even close as they dont have a big matrix of needles with top end and mid
taper changes.Makes tuning a twin more than twice as hard.
Plus no fine tune powerjet.
The trick venturi shape is more suited to great throttle response for say buckets on a kart track, or MX.
They have apparently recently done some more needle combinations, but I havnt had time yet to look into this.

Re the Lectrons bottom end tuning on the overun Rich,simply turning the rod in 1/4 turn increments makes for super easy changes in off idle fuelling.
And as I said about the TZ400, it had 4-2 needles with big powerjets, so simple next step is a 5-2 with smaller PJs - will end up with same egt and better part throttle corner response.
No effect on the bottom or mid tuning, just rearranging the top end.
The 300 motors will end up making some more power than the old TZ based 400s - 86RWHp so that motor is a bit overcarbed, but the HV venturi helps the mid response a heap.
One of the 300 customers wants some 38PJs so maybe you can do the Lectron thing for no outlay.

[oktrg500]

Hi,

One subject which isn't discussed often here is the air intake system. In my book turbulent air = no good. Hot air = no good. For sure, designing a good air feed system isn't that easy, or is it?

I found one previous discussion about this topic starting here http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130747647#post1130747647

It seems to me most of the buckets are running open air carburation, with a few exceptions using KN filters.

Quoting Frits: "Is an airbox on a bucket worth bothering? Definitely, but not so much because of that 1% ram-air pressure; its main purpose should be to feed cold air to the carb."

With my 125cc engine I'm in the category where the main purpose is feeding the carb with cold air.

I'm wondering about e.g. what the inside of the air box should look like. Most of the pictures of custom air boxes I've seen is just a big box with the carb inside. Fed from the front of the bike, I guess the air will be rather turbulent inside the box.

Any advice, pics and experiences you can share will be very much appreciated.

Thank you.

[oktrg500]

This >> https://www.facebook.com/Techgp/photos_stream?tab=photos_albums :Punk:

[husaberg]

Airbox stuff is mixed in here
http://www.kiwibiker.co.nz/forums/album.php?albumid=4844

[husaberg]

http://fs2.directupload.net/images/150227/temp/g2nyq3cw.jpg (http://www.directupload.net/file/d/3911/g2nyq3cw_jpg.htm)


No surprise that a 500ccm engine does not give more power than a 125ccm gp engine if the cylinder is mistreated like this. "The power valve ports are slightly smaller...." :brick: So why using a 500ccm engine if you don`t let it breathe? unbelievable...:sick:

http://www.2tprofessor.com/blog.html
This also has a thread on Pitlane plus I think he has occasionally posted on here.....

[Martin1981]

http://www.2tprofessor.com/blog.html
This also has a thread on Pitlane plus I think he has occasionally posted on here.....

yes husa. and the guy asked Jan Thiel how much hp is possible with a 500ccm single. jan told him that it can pump out up to 140hp!.....if everything is done right....if this is too much power then one shold reduce the engines cylinder volume, and not choke it!


same with 4 stroke engines....first engines with big volume or turbochargers are built and then they get choked by air restrictors:brick:

[senso]

Sweet two stroke jesus, would love to see even a 120hp 500cc single, staying on the bike would be a challenge. :gob:

[richban]

Re the Lectrons bottom end tuning on the overun Rich,simply turning the rod in 1/4 turn increments makes for super easy changes in off idle fuelling.
And as I said about the TZ400, it had 4-2 needles with big powerjets, so simple next step is a 5-2 with smaller PJs - will end up with same egt and better part throttle corner response.
No effect on the bottom or mid tuning, just rearranging the top end.
The 300 motors will end up making some more power than the old TZ based 400s - 86RWHp so that motor is a bit overcarbed, but the HV venturi helps the mid response a heap.
One of the 300 customers wants some 38PJs so maybe you can do the Lectron thing for no outlay.

This all sounds great. On the shopping list for sure.

Re the PJ38's. I don't have any but other Richard does. Not sure he would let them go. I am running the modified PWK power jet air strikers, YZ250 carbs TPS etc. They are working well but are running at the angle limit now and the last needle position. The bike thats running the PJ's is running some big jets to keep things together when the ram air is on song. But this has caused 3/4 throttle issues.

309699.

[senso]

Sharing another job in another cast iron cylinder.
What do you guys think about what I have done, any stupid mistake?
Original vs ported(never liked this word :/ )
The paper is not there to hide anything, its just so my very,very old camera can focus in the plane of the ducts.

309713

309714

309715

[adegnes]

^looks great! Well done.

[wobbly]

Make the ball nose radius on the bore/duct edge way bigger - like this pic I have posted 20 times.

Re airbox - for bucket bikes if you can fit it in it will be about the right size, and having a duct from somewhere in front of the bike will keep the air cool.
As long as the inlet to the box doesnt have air flowing across the carb mouth turbulence wont be an issue, the entry air speed isnt high enough to cause any problems.
Have dyno tested this on a 100 bucket, the airbox and snorkel with no ram, was worth about 1 1/2 Hp in 28.6.

[adegnes]

Regarding airboxes - any advice on what I should do in this scenario, without adding too much to the width of the bike?
I'm not concerned about filtration, but about the "air brush effect" from air passing the carb at 90°...
309717

[husaberg]

Regarding airboxes - any advice on what I should do in this scenario, without adding too much to the width of the bike?
I'm not concerned about filtration, but about the "air brush effect" from air passing the carb at 90°...
309717

But ditch the ram air you won't need it at road speed and it will only serve to bugger the carburation
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=304384&d=1413875764
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=304383&d=1413875763
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301391&d=1411374076
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301392&d=1411374076
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301393&d=1411374076
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301394&d=1411374076
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301395&d=1411374076
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301396&d=1411374076
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=301312&d=1411373100


Intake Temperature and Horsepower Loss

Estimate power loss or gains due to air temperature changes



HP Output = +1% HP per 10 degree temperature decrease
-1% HP per 10 degree temperature increase
I have seen much higher figures used.............note the temp will be in degrees F

http://www.aemintakes.com/temperature_testing.htm
http://www.aemintakes.com/images/tempreture_testing_formula.gif

[peewee]

Re airbox - for bucket bikes if you can fit it in it will be about the right size, and having a duct from somewhere in front of the bike will keep the air cool.
As long as the inlet to the box doesnt have air flowing across the carb mouth turbulence wont be an issue, the entry air speed isnt high enough to cause any problems.
Have dyno tested this on a 100 bucket, the airbox and snorkel with no ram, was worth about 1 1/2 Hp in 28.6.

whats your thoughts for a drag racer in atv configuration. seems most people just use k&n pod filters attached to the carbs, no airbox. the chassis is completely open with no fairings. would it even be worth the trouble to try and make a airbox or just stay with pod filters ?

[Dodgy]

One of the 300 customers wants some 38PJs so maybe you can do the Lectron thing for no outlay.

I have a set of PJ38s that I purchased for my road NSR300 that I never used. I offset bored the standard carbs and although prob not perfect at 33.5mm, it is only a roadbike after all.

Interested in selling on the PJ38s.

[bucketracer]

Regarding airboxes - any advice on what I should do in this scenario, without adding too much to the width of the bike?
I'm not concerned about filtration, but about the "air brush effect" from air passing the carb at 90°...
309717

309725

Back several 100 pages are posts where at a Taupo race meet, TeeZee found that he needed to protect the carbs bell mouth from air blowing directly across it and upsetting the carburation so he fashioned this crude but effective wind break from an ice cream container. As an aside, he also posted dyno graphs of 29 rwhp with that pumper carb like it is, without a bell mouth, he said, in back to back tests bell mouths seemed to do nothing for it.

309723309724

He later made a better job of it using stiff rubber sheet. He said he would like to try it the other way around so it scooped air into the carb but was worried that it would just as effectively scoop up road gravel in the event of a crash. The way he has it in the pictures he hoped the rubber would fold over and cover the carb if the bike fell over.