ESE's works engine tuner

[wobbly]

Been away testing/racing again and missed a few days on here.
The real world testing I have done with carb inserts is restricted to big VM round slide Mikuni carbs as we are forced to
use in pre82 Classic bike racing.
The company that makes the cheese cutter cross piece to fit in the front of the carb also make a plastic UFO thing that fits into the bottom of the slide.
The huge increase in flow velocity over the pilot circuit from the slide insert required dropping the jet from a 65 down to a 32.5.
All i can say is that with the 38mm round slide Mikuni as fitted to a TZ350, when both of the items are fitted to the carb and the tuning is corrected
the old piston port engine has gained near on 1000 rpm of useable bottom end power and now easily wheelstands the first 3 gears out of every slow corner.
It would never do that previously , and has a night and day effect on throttle response on track.
Again it enabled a 71 year old to kick arse with the young guns whether they were on a TZ or a Pantah, no snake oil - the inserts work.

[husaberg]

True but the power drain on the motor does not increase by the square of engine speed like it would with a crank driven fan.

neither does a well designed cooling fan though either.. look how little the huge I assume vw fan consumes.........

[TZ350]

do any of you guys have experience with these things that go inside the carb bore, either before or after the slide ? is it just rubbish with a splash of snake oil ? The Quad-Flow Torque Wing has vertical and horizontal air flow stabilizers which increase air flow.

Hi Peewee, In the quest for improved performance I think everything is worth a look, I would love to test those flow straighteners.

The real world testing I have done with carb inserts is restricted to big VM round slide Mikuni carbs as we are forced to use in pre82 Classic bike racing.

The company that makes the cheese cutter cross piece to fit in the front of the carb also make a plastic UFO thing that fits into the bottom of the slide.

The huge increase in flow velocity over the pilot circuit from the slide insert required dropping the jet from a 65 down to a 32.5.

All i can say is that with the 38mm round slide Mikuni as fitted to a TZ350, when both of the items are fitted to the carb and the tuning is corrected the old piston port engine has gained near on 1000 rpm of useable bottom end power and now easily wheelstands the first 3 gears out of every slow corner.

It would never do that previously , and has a night and day effect on throttle response on track.
Again it enabled a 71 year old to kick arse with the young guns whether they were on a TZ or a Pantah,

no snake oil - the inserts work.

There you go Peewee ......

[190mech]

I feel a proper cooling duct system would help greatly,Look at the old NACA files,L4I11d and No.1092.These deal with large radial aircraft engines that run very cool at high power settings with careful duct work,,just food for thought....

[peewee]

like husaberg said, why do we not see dividers in the rsa125 inlet track ? perhaps they can work well in engines with inferior intake designs.

[Yow Ling]

like husaberg said, why do we not see dividers in the rsa125 inlet track ? perhaps they can work well in engines with inferior intake designs.

Maybe they work in engines where the riders ride part throttle much of the time, which probably isnt an RSA125, they look like they reduce some of the turbulence caused by the partially opened slide. From what I have read here RSA does not like partial throttle openings and causes it to detonate and run badly

[TZ350]

I feel a proper cooling duct system would help greatly. Look at the old NACA files,L4I11d and No.1092 - food for thought....

Found and downloaded it, thanks.

[wobbly]

The experience with the VM round slides has no relevance whatsoever to a RSA125.
Thats like looking for some similarity in a Nascar tunnel ram to a ITB intake on a MotoGP bike.
Apart from the fact that the tract length differs by a factor of 2 and the RSA has a flat slide with no severe flow disruption at the sides or under the slide cutaway , even loosely comparing
a rotary valve inlet with timings of 140/90 to a piston port with 98/98 timing is an exercise in blind futility.
The RSA has a digital ignition with a shit load of mid advance and a powervalve to boost mid response - the TZ350 has neither , so an exercise in improving the old engines
efficiency is bound to have a dramatic effect in the main area of deficiency for a big carb on a piston port intake, part throttle response - as it is so crap to begin with.

[husaberg]

The experience with the VM round slides has no relevance whatsoever to a RSA125.
Thats like looking for some similarity in a Nascar tunnel ram to a ITB intake on a MotoGP bike.
Apart from the fact that the tract length differs by a factor of 2 and the RSA has a flat slide with no severe flow disruption at the sides or under the slide cutaway , even loosely comparing
a rotary valve inlet with timings of 140/90 to a piston port with 98/98 timing is an exercise in blind futility.
The RSA has a digital ignition with a shit load of mid advance and a powervalve to boost mid response - the TZ350 has neither , so an exercise in improving the old engines
efficiency is bound to have a dramatic effect in the main area of deficiency for a big carb on a piston port intake, part throttle response - as it is so crap to begin with.

Can you post a pic what the ufo filler under the slide looks like Wob?

[Ocean1]

neither does a well designed cooling fan though either.. look how little the huge I assume vw fan consumes.........

VW has an extremely sophisticated method of correcting the exponential power requirements of the fan so that it closely matches just the required air flow for cooling.

The vee belt slips.

[Frits Overmars]

The best boats in our sort of boatracing have been coming from Europe, but in the last couple of years, some American builders have started producing their versions.

So apparently have some youngsters in Thailand (where Jan Thiel happens to live nowadays ): http://www.youtube.com/watch?v=ybpdNcMPs8s

[wobbly]

http://www.thunderproducts.com/u_f_o.htm

The marketing bullshit with the parts like UFO and Quad Torque Wing are the products of a very fertile imagination but in the case of the old VM round
slide carb the improvements are repeatable and for sure worth having - where you are forced to use them due to tech regs.
There may be cases where the flow disruption of the stainless X insert may offset any gain in response, but in a TZ350 this isnt a limiting factor.
I thought about this seriously after doing the TZ400 with 40mm HV Lectron flat slides ( period legal in Pre 82 ).
This setup had such superior throttle response on the dyno, when compared to the shitty Bwwraap Bwwraap stumbling against any applied load, of the VMs, even when tuned as well as possible.

[adegnes]

First of all I want to say thanks for all the great info in this thread!
First time posting here, but I've been lurking for a while.
I'm from Norway and I enjoy fiddling with small two strokes.

Currently I'm building 50cc rotary valve single variated engine, and I have a few questions I thought maybe you could help me out with.
This is a shameless thread-jack, so please let me know if I should start a new thread.

Questions:
1. In the attached picture you can see how I cut the transfers and the inlet. I aimed the inlet upwards a bit, my thought was that the incoming charge would kind of jump the crank webs. Should I just remove the "kicker" and aim straight in, and focus more on flow "around" the webs?

2. I'm planning to run on e-85, when building a pipe after Frits' FOS concept, whats a good starting point number for speed of sound? Lower speed than for pump gas I suppose?

Thanks!

[TZ350]

Your questions about the inlet are interesting, I would like to know too.

Currently I'm building 50cc rotary valve single variated engine

Please keep posting pictures and reports as your build progresses.

[Frits Overmars]

I aimed the inlet upwards a bit, my thought was that the incoming charge would kind of jump the crank webs. Should I just remove the "kicker" and aim straight in, and focus more on flow "around" the webs?

It's hard to tell from just one picture, but I get the impression that you aimed the inlet upwards more than just a bit.
Put a piston in a cylinder at BDC; then put that cylinder on your crank case and look through the inlet hole. Chances are that the piston is right in the way of the flow path, so you may want to lower that path. Remember that the flow must be able to reach the opposite transfers. If you need a 'kicker' at all, the crank web bevel will do that for you.

I'm planning to run on e-85, when building a pipe after Frits' FOS concept, whats a good starting point number for speed of sound? Lower speed than for pump gas I suppose?

I haven't used E85 yet; you could be right. You'll just have to find out by trying.