ESE's works engine tuner

[jasonu]

I saw this carb 'wing' as part of a listing for a 2002 CR250. Apparently it improves low end throttle response.

[wobbly]

We tested that carb blade on Grumpys TZ350 with 38mm long bell round slide Mikuni carbs.
It did increase the throttle response off slow hairpins where the tall TZ gearing forced the engine off the pipe.
But what worked even better was fitting plastic UFO inserts into the hollow under the slide.
With these the pilot was reduced from a 60 to a 35 ( way more idle signal ) and then it really jumped out of corners ( for a piston port that is ).
The insert needed modifying with a bigger hole around the emulsion tube shroud, to prevent fuel being dragged past the needle on zero throttle/high rpm
that caused mid corner roll on richness.

[husaberg]

We tested that carb blade on Grumpys TZ350 with 38mm long bell round slide Mikuni carbs.
It did increase the throttle response off slow hairpins where the tall TZ gearing forced the engine off the pipe.
But what worked even better was fitting plastic UFO inserts into the hollow under the slide.
With these the pilot was reduced from a 60 to a 35 ( way more idle signal ) and then it really jumped out of corners ( for a piston port that is ).
The insert needed modifying with a bigger hole around the emulsion tube shroud, to prevent fuel being dragged past the needle on zero throttle/high rpm
that caused mid corner roll on richness.

Cameron writes about that effect quite a few times, he says it is the reason flat slides were re-developed to decrease the underslide volume.
https://books.google.co.nz/books?id=...page&q&f=false
https://www.kiwibiker.co.nz/forums/a...3&d=1482399423
yeah i know about the reed pooping open bit being wrong

[Flettner]

Aren't carburetors and all associated crap in the inlet just a restriction?
EFI is most certainly the future and I might add, rotary valve.

[wobbly]

A bit hard to find a way to be allowed to put efi and rotary valves on a Pre 82 Junior TZ350 Yamaha.

[Grumph]

A bit hard to find a way to be allowed to put efi and rotary valves on a Pre 82 Junior TZ350 Yamaha.

Neil's going to have to do a roadrace Bighorn...Still legal for F3 or whatever it's called now.
Have to run it on petrol though...

[husaberg]

Neil's going to have to do a roadrace Bighorn...Still legal for F3 or whatever it's called now.
Have to run it on petrol though...

If he did a Rotax/Can-Am big bore 350 it would be Bears legal on the Vodka.
But all his own home made engines are also bears legal

[Flettner]

And there she Is, what a bighorn should have evolved into.

[WilDun]

Aren't carburetors and all associated crap in the inlet just a restriction?
EFI is most certainly the future and I might add, rotary valve.

Are you still using a (restrictive) throttle slide on the Bighorn, or is the "throttling" being done (or ever likely to be)
on the new one, by variable inlet opening/closing timing on the rotary valve?

[Grumph]

And there she Is, what a bighorn should have evolved into.

I've always thought Kawasaki should have done a tandem twin double Bighorn for the tighter circuits used for the F750 Title.
Even got the obvious name - the Longhorn...

But yours is nice too....

[Flettner]

Yes Will, the 'throttling' is done by the rotary valve slides (gibbs), one for open and one for shut side. there will be just a bell mouth attached to the inlet you see. The two little tubes you see sticking out house small needle rollers that support the shafts that drive these gibbs. So when wide open, up on song, there is just a very short inlet with nothing in the way. I am considering having a hole on the other side of the crankcase that opens up like a 24 /7 reed principal. Not in this first engine though. Fits real nice in this frame and its now got a YZ250X wide ratio gearbox.
FMF fatty is in for the chop, rear exhaust with a mid chamber bleed to keep the pipe short (and quiet) enough.
I know this has all been shown a million times but for those that don't understand the sliding gibb principal, here is my Bighorn one.

[Flettner]

I've always thought Kawasaki should have done a tandem twin double Bighorn for the tighter circuits used for the F750 Title.
Even got the obvious name - the Longhorn...

But yours is nice too....

You and me both Grumph, but I think better will be the V twin that this project is the prototype for. Two times what ever this pans out into.
%#$%^& en Kawasaki they should not have dropped the rotary valve.

[speedpro]

Modern engine management makes things like rotary valves a good idea nowadays. Without the wizardry not so much. Think back to early buckets and all the bob weights and springs used to make variable dodads, or variable valves working against springs with tapered needles and interchangeable jets and variable spring preload. All replaced with a couple of look-up tables.

[Muciek]

Rotary valve TZ, and a lot of other "weird" stuff on this bike https://www.facebook.com/coeno.vanho...6864493&type=3

[Muhr]

Hello guys this I my first post!

I've followed this thread for a while and you guys seem to keep up with a lot of fun stuff.
I'm doing a small hobby project that is a bit out of my comfort zone (a rotary valve 100cc V-twin 90 °).
I was wondering if there is someone who has some heads up regarding twin rotary valve assembly?

best regards Johan