ESE's works engine tuner

[Buckets4Me]

I think perhaps you may be missing the whole point of the thread ?

Rather than being a "look at me and how smart I am" collection of worthless shit, I think it is intended to be more of a "here is some useful things I have found, that have made my bike go better".

I think he is sour that we havent posted anything about hotting a vespa up
apart from what not to do



cutting cranks up and heat treating your bike is not the way to go

[TZ350]

So SS90 keeping to the facts without inventing stories is useful too or should we just disregard all of your tuning posts as meaningless hot air.

Keeping to the facts is probably not a bad idea, we hadn't over cut the springs, but SS if we had fucked up, so what, why try and make us look bad…...whats your problem...

I think perhaps you may be missing the whole point of the thread ?…….I think it is intended to be more of a "here is some useful things I have found…….

Thanks Gatch..…..that’s it exactly, it’s a hobby, and we enjoy it……..might even be getting good at it..........

Take advice with grain of salt where preferred..

Yep, it's how we see it……..we post everything we can, links, formula, pictures and hand drawings so that anyone can judge for themselves whether to “take it, or leave it” ………

[Yow Ling]

Meanwhile, back at the track yesterday, (big track) I accidentally trashed 2 engines. I think they both bottom ends , i sure about one cos I looked !
30:1 motul 800 . Must be a bit lean, I expected if it was a bit lean maybe I would seize a piston, wasnt really ready for a bottom end. Some opinions would be good. Engine is KC100 . Was going pretty good until then. One was halfway down the straight full noise, the other was exiting the dipper at ruapuna

[TZ350]

.

Thomas and Bucketracer have setup something using an old vacuum cleaner motor and a bucket and we hope to be able use a manometer to check on the symmetry of the transfer streams.

Will let you know if the idea proves usefull.......

[TZ350]

Meanwhile, back at the track yesterday, (big track) I accidentally trashed 2 engines. I think they both bottom ends , i sure about one cos I looked !
30:1 motul 800 . Must be a bit lean, I expected if it was a bit lean maybe I would seize a piston, wasnt really ready for a bottom end. Some opinions would be good. Engine is KC100 . Was going pretty good until then. One was halfway down the straight full noise, the other was exiting the dipper at ruapuna

We use a cheeper oil, Shell Advance Ultra at 20:1 in the Buckets, because with so many people involved it is more reliable to say "tip the 1l bottle into that 20l drum" than have them work out oil/fuel ratios.......also we have brought into the, more oil for more power idea...........

Ran Motul 30:1 in my TZ ok..........Should have been ok in your KC........sorry to hear about the B/E failures.....

[TZ350]

Certainly can measure pressure differences around the cylinder and in spite of its 20rwhp this one looks like it has the dreaded tongue pattern so it could be better.

The next step is to make a Perspex head with pressure taps so I can make repeatable measurement.

[F5 Dave]

Meanwhile, back at the track yesterday, (big track) I accidentally trashed 2 engines. I think they both bottom ends , i sure about one cos I looked !
30:1 motul 800 . Must be a bit lean, I expected if it was a bit lean maybe I would seize a piston, wasnt really ready for a bottom end. Some opinions would be good. Engine is KC100 . Was going pretty good until then. One was halfway down the straight full noise, the other was exiting the dipper at ruapuna

These days I always rebuild a bottom end before using it. If done properly it should give years of reliable service. I use Motul at 30:1 in the 50 & it revs to the moon. I used to kill a few bottom ends when I was racing the MB50. I'd buy another engine for a hundy or less & carry on. Then it would die again several races later. Engines that have been sitting around corrode & the plating gets knackered. From there is is only time to when the bearing slides instead of turns. As soon as there is a slight flat it is curtains within seconds. Once I rebuilt with new my problems (for that reason) stopped.

Further issues could include waay too high compression or detonation which hammers everything downstream of the sparkplug. You'd likely see evidence of this on the piston.

[TZ350]

........... when the bearing slides instead of turns. As soon as there is a slight flat it is curtains within seconds..........

The Z's and TR's if they holed a piston the alloy dust would jam the B/E and skid the rollers. Didn't matter how well you cleaned the B/E out it would fail not long after, only fix was to replace the B/E brg after holing a piston.

Same problem with the bike sitting around over winter after using (hygroscopic) Castrol R in it, the rollers and B/E pin would develop corrosion spots and it was curtains for the B/E pretty quickly.......mains too.....

[Yow Ling]

that may be part of the problem, both bikes have been stored and unused for several years. I wish that it was the owner of the second bike riding it at the time!. No mind, Ive been rebuilding a few cranks lately, so a couple more will be good practice

[aircooled]

fork geometry would surely have to change after the forks are compressed, ie rake & trail ?

[Henk]

Rake and trail both decrease every time you compress the forks, this is why bikes tend to turn much faster when you are hard on the picks in an outbraving manuvoure and also why front ends have a tendency to wash as you give it too much welly on the bars turning during said stupidly late braking exercises.

[SS90]

I think he is sour that we havent posted anything about hotting a vespa up
apart from what not to do



cutting cranks up and heat treating your bike is not the way to go

Wow, you clearly have no idea what you are talking about..... all my high end Vespa tuning cranks are cut like that now, (as well as any other tuner worth his salt in this game) and, they vibrate less than their "full circle" origins.

Actually, you can now buy that style of crank from wholesalers....

Since it is clear you have absolutely no industry experience or training whatsoever, you are commenting WAY outside your paygrade.

Perhaps if you actually did some tuning work, you would understand.

I will put it really simply.... to get a power curve with a wide rpm power band, you need to have an exhaust baffle angle like the one in the picture I have previously shown (which, actually was the same engine as the crank you keep referring to is fitted....but I have made 9 others since, to the same specifications, only I use a jig now), to get the full benefit of such an exhaust, you need to have a high crankcase volume (low ratio) around a ratio of 1.40, or perhaps less in some cases.

Every engine does not get that style of crank, but all the high power engines do.

Clearly they need to have a reed valve fitted to even funtion, so it is a matter of budget for the customer.

Removing material from the crank is the only realistic way to do this, and in such a fashion so that I get a balance factor of somewhere around 50 to 56% (depending on the piston used) suits the fact that the engines spin to 10,000 rpm.

If I ran the "full circle" crank (this is not an original part, it is an accessory "old school" design, which also gives a primary compression ratio way to high), then the balance factor is around 25%....... not really suitable for an engine spinning to 10,000 rpm (sometimes more....some engines like Falc's spin to 12,000 rpm)


Actually, if you run these "full circle, high primary compression" cranks, the vibrations a so severe, they brake handlebars over time, even when only revved to 6,000 rpm.

Clearly 25% is unsuitable for any thing "high revving".

Factors I use when deciding which crankshaft to use (oh, by the way, they all look similar to the pictures I posted), comes down to what piston the customer wants, what ignition, and, most importantly, which exhaust.

If a customer wanted to use a certain type of exhaust (for what ever reason), then I would use my experience to decide what primary compression ratio (among other factors) would suit his exhaust, as well as what cylinder head design.

As previously mentioned, if budgets allowed, I could perfect the balance factor for each situation, using titanium slugs opposite the pin, but it is not really needed as the vibrations are less that original. (at "race pace")

I did drill out the centre of a crank pin a year ago.... essentially the same effect as adding Titanium to the opposite end ....and free, but it was so soft to drill that I suspected it would shorten the service life of the crank to a level that was unnacceptable for every day customers... it would likely be ok if you out a new rod kit in every 100 hours..... but like I say, the engines vibrate much much less than the original 25% balance factor you get if you just assemble on eout of the box (and, again gives you much to high primary compression to boot) I also feel that removing any more material from around the big end would be courting disaster as well.

Oh, and Bucketsforme, your continual game of pretending not to understand this concept does not frustrate me in the slightest, it just goes to show your level of intellect.

There are plenty of manufacturers that use this design of crank.

You know, I would go so far as to say that if you where building an air cooled 125cc two stroke, and you didn't use values similar to those achieved when you use a crank like this (in regards to balance factor and primary compression ratio's), then you would do well to find another hobby/career.



Your constant belittling of the fact that I deal with Vespa engines is a clear indicator of your lack of understanding of the size of the world and just how big the industry is in Europe and America.

If you think you can build air cooled 125cc engines making more than 25 horsepower and only having 4 gears, then come over here and prove your worth.

[speedpro]

. . . you need to have a high crankcase volume (low ratio) around a ratio of 1.40, or perhaps less in some cases.

Every engine does not get that style of crank, but all the high power engines do.

Removing material from the crank is the only realistic way to do this, and in such a fashion so that I get a balance factor of somewhere around 50 to 56% (depending on the piston used) suits the fact that the engines spin to 10,000 rpm.

Interesting comment about crankcase volume.

Looking at the flywheel, and considering that you mention a 50-56% factor I think you must have reasonably heavy reciprocating mass. Are the pistons you use heavy compared to say a KT100?

My current crank has a balance factor in the same region and I haven't removed anything like that amount of material. The pin I'm using, which has an offset centre section, has a hole in the middle about the same size as a standard pin's hole. I suspect you could go quite big without compromising strength provided the material was decent. I've also drilled 2 holes in each web in the vicinity of the crankpin plus because the rod big end is wider there is 1mm off each web face surrounding the pin.

[speedpro]

I also wonder if we are specifying balance factors in opposite ways.
Looking at that crank it seems to me that the factor has been increased. If it got to 100% the engine would only ever be balanced at standstill. With less and less % it becomes balanced at higher and higher rpm. 25% would be for incredibly high rpm, engine wise, considering as you say that 50% is for around 11-12,000rpm. 75% however would be for a lower revving engine which would vibrate badly when revved like my old TS100 before I rebalanced the crank.
Again, looking at that crank I think it has a lot of mass opposing the piston and therefore a high balance factor, unless there's things done that I can't see, like the titanium slug you mentioned. Or maybe a slug of mallory metal in the bigend pin??

[TZ350]

Suspension

fork geometry would surely have to change after the forks are compressed, ie rake & trail ?

Rake and trail both decrease every time you compress the forks, this is why bikes tend to turn much faster when you are hard on the picks

Yes you are right, there is an overlap between fork geometry and spring rate and damping.

Basically fork geometry is about steering, not suspension.

Suspension, spring rates and damping is something different, suspension is about keeping wheels in contact with the road.

Fork geometry and suspension, are different things, but one does compromises the other, its the usual engineering trade off.

I agree with Thomas, the better technical posts are backed with facts and references and competent opinion pieces are illustrated with pictures and drawings.