ESE's works engine tuner

[TZ350]

Are you experimenting with the variable tailpipe area that was designed by Frits Overmars ?
http://www.pit-lane.biz/t3173p60-gp1...-part-2-locked look at page 3

Not variable tailpipe area but I did try varying the pipes internal working pressure with good results.

Attachment 279980

Tried it open and closed, Red open, Blue closed. The big surprise was how quiet it was when open, hardly any more noise at all, certainly wouldn't need any sort of muffler.

[katinas]

Katinas, congratulations on your build, and progress.

I'm puzzled about some things.

How do you stop the piston from rotating on the thread?

What do you use the vertical cylinder for?

Hi,

Main piston and steel tube screwed with hi-temp locttite with aluminium powder ( for cylinder block liners) so its solid.
Bottom aluminium part screwed and fixed with special screw.
Vertical breathing cylinder, is tube with reed valve (like on four strokes), returning oil tube and foam filter.
Add pic.

[tjbw]

Hi,

Main piston and steel tube screwed with hi-temp locttite with aluminium powder ( for cylinder block liners) so its solid.
Bottom aluminium part screwed and fixed with special screw.
Vertical breathing cylinder, is tube with reed valve (like on four strokes), returning oil tube and foam filter.
Add pic.

Thanks katinas, all is clear with your excellent sketch.

[lodgernz]

I need some advice please folks. I currently race a Honda 50 which runs very happily with a 24mm Mikuni Flat Slide with 28º downdraught.
I'm replacing that carb with a 26mm genuine OKO, but due to some other mods, this carb will need to be mounted with 35º downdraught.
Am I going to have problems?
Would a genuine Keihin be any better?

[diesel pig]

I need some advice please folks. I currently race a Honda 50 which runs very happily with a 24mm Mikuni Flat Slide with 28º downdraught.
I'm replacing that carb with a 26mm genuine OKO, but due to some other mods, this carb will need to be mounted with 35º downdraught.
Am I going to have problems?
Would a genuine Keihin be any better?

I know at 38 degrees from vertical raw fuel run straight out the idle circuit on my PWK keihin flooding the motor brought it back to 13 degrees and it run fine. Since OKO are based on Keihin's you may have the same problem.
I think Wobbly or Grumph mention Keihin's can only go to 15 or 16 degrees from vertical before you have major problems with fuel pick ups in the bowl.

[wobbly]

No way will any Keihin or OKO run at those angles - the fuel level in the bowl is then higher than the idle jet exit hole, so fuel simply pisses out - even before you stomp on the front brake.
The only carb you can use to straighten out the inlet and run at that sort of angle is the Keihin downdraft as used on NS250 - 400 or even better a small Lectron.
Frits countrymen use 30mm HV ( 26mm venturi ) Lectrons in all manner of 50cc rockets for that very reason.

[husaberg]

I need some advice please folks. I currently race a Honda 50 which runs very happily with a 24mm Mikuni Flat Slide with 28º downdraught.
I'm replacing that carb with a 26mm genuine OKO, but due to some other mods, this carb will need to be mounted with 35º downdraught.
Am I going to have problems?
Would a genuine Keihin be any better?

Mikuni TM28SS from a tzr250 IKT or a KR250 (the tandem disc valve one) I think a Dt200 may have also had this carb.



or Yoshimuras YDMJN looks rather neat it actually looks like a mix of Mikuni and keihin bits
It actually wasn't as expensive as you would have thought for a brand new limited production carb.



Your other option is a Keihin downdraft off a MVX250 (Hens teeth)as they were about that size, Some say 24 some say 25mm but same basic body as the nsr250 carb.

[lodgernz]

Thanks for your help everyone, re my carb downdraught issue.

[katinas]

No way will any Keihin or OKO run at those angles - the fuel level in the bowl is then higher than the idle jet exit hole, so fuel simply pisses out - even before you stomp on the front brake.
The only carb you can use to straighten out the inlet and run at that sort of angle is the Keihin downdraft as used on NS250 - 400 or even better a small Lectron.
Frits countrymen use 30mm HV ( 26mm venturi ) Lectrons in all manner of 50cc rockets for that very reason.

Honda NS 250 -28mm.

Honda NS 400- 26mm.

But these carbs works best with original airbox with foam filter. Anyway so much modification is needed and not just like change main jet, but with emulsion tube, needle, power jet, etc., because no acceleration.

[shnaggs]

Yes I have that in hand, but not move the pipe.

Curious if you have similar idea as I have. Does it involve an "American style" football shaped butterfly with a hole in the corner that sits in the convergent cone?

[F5 Dave]

Give us a yell Roger. We'll hook you up with nsr or mvx carb.

[Flettner]

Curious if you have similar idea as I have. Does it involve an "American style" football shaped butterfly with a hole in the corner that sits in the convergent cone?

It might, how did it go .

[husaberg]

Curious if you have similar idea as I have. Does it involve an "American style" football shaped butterfly with a hole in the corner that sits in the convergent cone?

Draw a picture because i can't fathom that one.

[Flettner]

I guess the real way is to just build one and test it. With mine I was looking at taking the bleed off from the center section of the chamber anyway, so the 'flap' didn't need a hole in it. Shnaggs, have you tried this idea?

So, say you were to build a cylinder to test a Ryger bottom end, but a standard loop scavenge style, would it be appropriate to put the reeds straight into the transfers? Transfers would now be real short as the piston at this point is also real short (just enough to house a ring or two). So the reed exit could be the transfer in itself almost? Four reed blocks? One for each transfer (A and B) and I guess four carburetors?
Or are we better off putting the reeds further down under the piston aiming up with the transfer flow direction.

I have two bottom ends to test, both seen here earlier but now with 7075 rods, hard chrome plated, against an aluminium bronze bush, under oil pressure. I've got several FOS type cylinders to test BUT I would like to start off with something a little more known, loop scavenge. Both systems will probably need balance shafts but who cares for test.

Where would YOU put the reeds Luc?

Frits, would Ryger have been bleeding small amounts of hydrogen into the inlet to assist with HCCI (spark induced HCCI)? Did you see any funny little unaccounted for pipes near the carburetor? In the short video we did get to see (doctored sound) the kart seemed real/very gutless until it came on song, I thought indicating very retarded ignition timing ,required for spark induced HCCI I would imagine.

[Frits Overmars]

So, say you were to build a cylinder to test a Ryger bottom end, but a standard loop scavenge style, would it be appropriate to put the reeds straight into the transfers? Transfers would now be real short as the piston at this point is also real short (just enough to house a ring or two). So the reed exit could be the transfer in itself almost? Four reed blocks? One for each transfer (A and B) and I guess four carburetors? Or are we better off putting the reeds further down under the piston aiming up with the transfer flow direction.
Where would YOU put the reeds Luc?
Frits, would Ryger have been bleeding small amounts of hydrogen into the inlet to assist with HCCI (spark induced HCCI)? Did you see any funny little unaccounted for pipes near the carburetor? In the short video we did get to see (doctored sound) the kart seemed real/very gutless until it came on song, I thought indicating very retarded ignition timing ,required for spark induced HCCI I would imagine.

I haven't been near a Ryger engine since October 2015 so I cannot comment on anything that has been done since then (and I wouldn't be allowed to if I could).
There were no unaccounted for pipes anywhere then.