ESE's works engine tuner

[Frits Overmars]

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...

[husaberg]

grabbed what i thought was a Piatti AMC engine cylinder.It turns out it was not what i thought it was.

It has a very British Hepolite piston +60 thou it has massive transfer cut always so very un-villiers.

It also has unusual transfer bulges outside of cylinder so again un-Villiers but no transfer slots and a flat top piston.
It may be the mark 2 version mentioned in the Villiers article i posted? Also judging by the bore it must be a 250.
it is unbelievably heavy compared to the 8e/9e.

Most unusually it has a heart shaped inlet port. poor quality pics sorry as now, i can't find my camera.
Can anyone make a call on what it is?

I guess you may have to be over 60 to answer the question sorry

[cotswold]

I have been doing a lot of the Team ESE’s dyno work lately and gaining a lot of experience while getting paid to make engine parts after school for the Team as well as making an income building a special engine or two for customers, now some of our engines are leading the pack.

Attachment 257073

Having done a lot of the work helping TeeZee develop his 31hp Bucket engine, the Team recons that I have a few clues, and a bit of talent and can now call myself a real industry insider with a bit of worthwhile tuning knowledge and experience...........

Looks like you are doing a great job!

[wobbly]

The other thing to add to that Frits is a lesson that was well taken from Harold by me.
He made a reed setup that had large stuffers down each side of the block.
The logic was that Yamaha's reed was way too big,loosing a heap of velocity as the flow exited the manifold.
The reed block he used - off a Honda.

[TZ350]

By a bit of clever machining Bucket managed to lose 15mm from the inlet tract length (it was 145mm). We will see how that goes tomorrow night.

You might also consider putting the restriction in the bellmouth if your rules allow it. That would mean you can have a considerably longer trailing ramp (the widening can start right after the bellmouth, i.e. under the throttle slide). It also means that only the air, not the fuel, has to pass through the restriction. That way the total mass that has to be accelerated through the restriction, will be about 8 % less.

Its a little grey, some people feel a carb should always be measured at the same point that the original manufacturer measured it, but yes the rules seem to allow carb mods and we have tried your idea before and it worked OK.

The interesting thing is, that the signal strength was much greater and we had to reduce the main jet, we went from 140 down to 100 which is the smallest we could get, made 31rwhp with the 100mj, maybe there is more if we could get smaller jets.

When I settle on a carb configuration Lectron are open to looking at providing them as 24mm specials if they like the design, then the carbs would be available on special order to anyone who wants one so they will be completely within the rules or a punter could save quite a few $$$ and modify something for themselves.

[dinamik2t]

TZ, you could buy a couple from ebay: http://www.ebay.com/sch/?_nkw=keihin...&_stpos=&gbr=1

[husaberg]

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...

The other thing to add to that Frits is a lesson that was well taken from Harold by me.
He made a reed setup that had large stuffers down each side of the block.
The logic was that Yamaha's reed was way too big,loosing a heap of velocity as the flow exited the manifold.
The reed block he used - off a Honda.

So the real secret to getting a Yamaha to run hard.
Is to put in a complete Honda engine then

[Kickaha]

So the real secret to getting a Yamaha to run hard.
Is to put in a complete Honda engine then

There used to be a kit in the states to change the nineties TZ125 to the same bore x stroke as the RS125

[2T Institute]

The 'kit' came out after the 54 X 54.5 TZ came out . The 56mm TZ is a right bitch to tune almost any usual tuning trick results in a loss of HP.

[Frits Overmars]

Its a little grey, some people feel a carb should always be measured at the same point that the original manufacturer measured it, but yes the rules seem to allow carb mods and we have tried your idea before and it worked OK.

'Some people' can feel all they want, as long as they stay away from me and the missus.
Reading a rulebook is every bit as important as preparing an engine. I practiced reading between the lines all my life, before I became a technical adviser to the royal dutch motorcycle union KNMV and (much more fun) to the dutch moped racing union SOBW, so I know how to read a rulebook. Before I joined, the moped rules stated for example that the carburetter should not be larger than 20 mm. But nowhere in the rulebook did it say that you could have only one such carburetter...

[Frits Overmars]

Its a little grey, some people feel a carb should always be measured at the same point that the original manufacturer measured it, but yes the rules seem to allow carb mods and we have tried your idea before and it worked OK.

'Some people' can feel all they want, as long as they stay away from me and the missus.
Reading a rulebook is every bit as important as preparing an engine. I practiced reading between the lines all my life, before I became a technical advisor to the royal dutch motorcycle union KNMV and (much more fun) to the dutch moped racing union SOBW, so I know how to read a rulebook. Before I joined, the moped rules stated for example that the carburetter should not be larger than 20 mm. But nowhere in the rulebook did it say that you could have only one such carburetter...

[speedpro]

Which is the exact reason for the wording of our rules being "carburation equivalent to a single 24mm carb"

[F5 Dave]

. . the moped rules stated for example that the carburetter should not be larger than 20 mm. ...

thats a pretty small carburettor, be hard to get a bore size of more than 8mm.

[speedpro]

thats a pretty small carburettor, be hard to get a bore size of more than 8mm.

This is why nobody likes you Dave.

[F5 Dave]

That's not what you said last night.