ESE's works engine tuner

[richban]

I do, which is what Yow Ling was pointing out

24.2.1 Solo motorcycles shall have two engine capacity classes:
F4 2 stroke 55-100cc
2 stroke 55-125cc air cooled
4 stroke 55-150cc
F5 2 stroke 0-50cc
4 stroke 0-100cc air cooled

So F4 has a capacity limit of 150cc

24.2.3 The maximum capacity for rebored engines shall be:
F4 2 stroke 55-100cc - 104cc
2 stroke 55-125cc air cooled - 130.5cc
4 stroke 55-150cc – 158.09cc
F5 2 stroke 0-50cc - 53cc
4 stroke 0-100cc - 104cc

The key word is rebored there is no allowance for going over the 150cc limit with stroking

Ok to shut you all up or maybe start more discussion. Engine was running a 64mm piston. I changed the stroke. That made it 169. Purchased a new sleeve REBOED IT to 62mm. Now 156 rebored. Totally within the rules.

[Kickaha]

Purchased a new sleeve REBOrED IT to 62mm. Now 156 rebored. Totally within the rules.

62mm is stock bore size, so the capacity increase isn't as a result of being overbored, it's a result of a longer stroke with a stock bore

[richban]

62mm is stock bore size, so the capacity increase isn't as a result of being overbored, it's a result of a longer stroke with a stock bore

Shut up. 64mm was what I had. So are you saying you are not allowed to change you crank config or stroke in buckets? Coz plenty of people have and calculated the change back to within the cc ratings.

[TZ350]

.

Sure, legalisticly the extra capacity is to allow over boring but I am comfortable with people using better pistons than the std ones and then de-stroking to get back within the capacity limit.

I personally have an RG50 thats over bored for a better piston and de-stroked 3mm for 49.9cc....and thats legal.

And I was expecting when the time came for a re-bore that I could use the extra capacity limit allowed to 50's for re-bores......... I hadn't realised some might think thats a grey area........ it's a curly one.. ... and I hadn't realy thought about it.....

I know my F5 motor with a standard brand x piston is < 50cc

So I suppose I could argue that my RG50 motor with a "standard piston" is < 50cc therefore oversize rebores and the little extra cc is within the rules as they are.

[Yow Ling]

Ok to shut you all up or maybe start more discussion. Engine was running a 64mm piston. I changed the stroke. That made it 169. Purchased a new sleeve REBOED IT to 62mm. Now 156 rebored. Totally within the rules.

When you purchased the new sleeve you bored it not rebored it
to rebore is "•Removing of the worn or damaged interior surface of a cylinder to create a new working surface.

Would be interesting to find out what the rules actually mean , otherwise they may as well scrap the 150cc capacity limit and replace it with the 158cc

If there was no benifit to be had by stroking the engine and returning to 156cc why would you bother?

[jasonu]

[QUOTE=richban;1129907168]Well if Speedpro is making 29.2hp within the rules...

29.2hp Yeah Right...

[jasonu]

Well if Speedpro is making 29.2hp within the rules then you 2 smokers can stay where you are. I am heading to the US to live soon and the loacal rules in Porland are 105cc water Cooled 2 stroke...Unlimited Mods 210cc air cooled 4 stroke ....Unlimited Mods 150cc water cooled 4 stroke ....Unlimited Mods They don't even have an air cooled option from what I se they are running dirt bike engines in everything. KX CRF ect

Where abouts in the States is this? Details please

[richban]

Would be interesting to find out what the rules actually mean , otherwise they may as well scrap the 150cc capacity limit and replace it with the 158cc

If there was no benifit to be had by stroking the engine and returning to 156cc why would you bother?

Yeh! Its all in the way you read them. All I see is a capacity limit. I have a modifiyed engine it is under the max capacity limit. Job done. There is no mention of crank mods in the rules. But yet lots of people mod them. Unless there is a big appendix out there with all the definitions listed. Its up for interpretation. If you feel really strong about it then maybe you should petition the rule makers.

Why bother. In the interests of development. To try and go faster. Why else

[richban]

Where abouts in the States is this? Details please

Not far from you. Portland. http://www.oregonsuperbikers.com/classes Maybe I might see you there next year some time. The tracks look good.

[speedpro]

The way I read the rules is you can change the stroke because it doesn't say you can't. However if the engine is over the stated capacity of 150cc for example then it has to be rebored to be legal as the maximum capacity is for "rebored" engines. Whether the stock liner is rebored in the case of a short stroke engine or a new liner is rebored it doesn't matter, it just has to be "rebored". As stated by Yow Ling it does say "re"bored not just bored.
Using the same logic it is illegal to use KT100 piston pin circlips which is why I only ever use stock MB clips.
It's academic, nobody is going to protest about it, we're al too tight.

[Kickaha]

Yeh! Its all in the way you read them. All I see is a capacity limit.

Which is 150cc

I have a modifiyed engine it is under the max capacity limit. Job done. There is no mention of crank mods in the rules. But yet lots of people mod them.

How many is lots? how many have used a longer stroke to gain capacity?

Unless there is a big appendix out there with all the definitions listed. Its up for interpretation.

Up for interpretation? Not really, it states quite clearly it is for rebored engines

Can you show me where it says you can gain that capacity over the class limit (150cc)by stroking?

[TZ350]

GP125 18+ rwhp: skim the barrel 1.5mm and “o” ring it, thin alloy spacer plate under the barrel and Suzuki RG250 pipe. Ex opens 86 deg ATDC and Trans opens 114 ATDC, std head , inlet timing 145/55 and carb mj 95.

GP125 20+ rwhp: skim the barrel 1.5mm and “o” ring it, thin alloy Spacer plate under the barrel and Suzuki RG250 pipe modified to RM125 specs, KX80 ignition. Raise the exhaust to open 83 deg ATDC, and widen to 70% of the bore, cut 30 deg from the closing point of the rotary disk, so inlet opens 145 BTDC and closes 85 ATDC. Set the mj 105 and ignition timing, 26-28 BTDC using a dyno.

Pipe dimensions Suzuki RM125 B/C page 82 Bell http://www.kreidler.nl/artikelen/per...raham-bell.pdf

Save the stuffing around and go buy one of these digital, programmable ignitions
http://www.ignitech.cz/english/aindex.htm originally posted by K14

The above mods will pull 20+ rwhp from a GP125, Ned's manages 23 after these simple changes.

[TZ350]

Well that was this years 2-hour, and Team ESE didn't exactly cover itself in glory.

My bike promptly suffered a lockup in practice, I have not investigated yet but suspect a meltdown from too much top end retard. No real problem as we had a spare bike.

But my teammate was out in B grade trying out his 50 and was knocked off in the sweeper by someone putting on the moves and trying to be a hero. Result knocked out, broken collarbone and a trip to Hospital in the ambo.

In the 2-hour itself, Pumber did the suicide thing, flinging himself up the road in grand style and skittling our star rider. Chambers got going again, although he was in some pain, he and Ned put up a real good showing until about the 1 hour 30 mark. Then a mystery electrical ailment brought it all to a stop, funny thing, it could be restarted, run for a bit and then the fire would go out again.

So that was Team ESE’s day, a meltdown, a ride in the ambo and a mystery electrical gremlin, but enjoyable all the same.

Still it could have been worse, Henk did the clasic thing and lent his spare bike to a couple of young guys who then beat him in the 2-hour.

Not being able to be out there myself, gave me the chance to watch some really good riding as Kel, Rick, Fixer to name a few were really flying…….

And as always, the people were great and it was a stunning day, near perfect conditions....

[Buckets4Me]

before having a small off at the fastest part of the track


NedKelly catching #69


Chambers before being skittled

[SS90]

...My bike promptly suffered a lockup in practice, I have not investigated yet but suspect a meltdown from too much top end retard.

If too much top end retard was the cause, you should expect to see erosion on the exhaust side of the piston crown (caused by the over heating of the exhaust port).

From your other posts I would be surprised, based on your exhaust port width (limited by no bridge) and data you have posted regarding ignition timing.

My experience is that terminal problems caused by too much top end retard is only applicible with ultra wide bridged exhaust ports, narrow unbridged ports simply do not have the width to allow enough hot exhaust gasses through fast enough to heat the piston crown terminally.

I would be very interested to see a picture of your piston!