Re: Diaphragm Type Carbs?

Jonathan Eaton /

Yea these single speed kart engines need em, they are single speed and spin up to about 17k rpm. Should do about 70 once all is dialed in, I have some redline kart oil on order for it. Here's it with the airbox off.


Re: Diaphragm Type Carbs?


Re: Diaphragm Type Carbs?

#CrazyWayne™ rocks. #CrazyWayne /

A cut and past from my profile info.

Tillotson racing carbs

49cc up to 80c V1L, Honda PA, pug 103 & AV10 moby with stock cases.

Venturi 18mm throttle Bore 22mm good carb for a 49cc street riper.

Venturi 19.8mm throttle Bore 25.40mm

49cc spinning12K+ RPM or over 60cc, big reeds

Venturi Diameter 20mm throttle Bore Diameter 26mm

63cc and up or track 49cc setup.

Venturi 22.50mm throttle Bore 25.40mm

Venturi 22.9mm throttle Bore 25.4mm

The newer tillys venturi shape and bleed ports work so much better in the mid-range down to 1/3 throttle.

Thy get funky when your not quit on the pipe at lower rpms but that how it is with all carbs.

The spring rate popoff is the key to the mid-rang jetting = to the slide and needle setting on a standard carbs tuning.

What throws off tuners is the hi low mix adjustments.

You have to think of its fuel feed as tho it's running down a long pipe.

The first part of the feed pipe has a 4 way tap with the left tap feeding the low speed and the right feeding the high speed.

After the 4 way tap you have a flow diverting presser regulating bypass tap.

The flow diverting presser regulating bypass tap controls all flow / presser and mid rang mix adjustments, AKA the popoff spring.

But if your hi low 4 way tap up stream is using more or less fuel you will need to change your popoff accordingly for the mid rang jetting mix.

So the hi low jetting mix titer-totters with the mid-rang jetting mix.

And the low RPM and hi RPM mix adjustments have a offset titer-totter with each other.

The upper mid-rang tends to adjust a touch with the hi RPM mix adjustment.

So a rich low can give you a lean hi, but a rich hi will make your low just a pinch lean.

Most fuck up by having a rich low and go so rich on the hi speed adjustment that it makes the lower mid-rang lean. (edited)

Re: Diaphragm Type Carbs?

Giovanni Giarratana /

Does that motor run on methanol or gas?

Re: Diaphragm Type Carbs?

Jonathan Eaton /

Its gas, 20:1 or karting or racing two stroke, as long as its rating for the high rpms it should be fine. The tillotsons are commonly used for methanol though since adjustments are made so easily on them, I don't think Ive ever seen a methanol powered rotary 2 stroke but id sure love to.

Re: Diaphragm Type Carbs?

Born to be WillD Wrote:


> I was thinking you meant diaphragm carb's like the

> ones on all the 4t modern carbureted bikes &

> scooters, where throttle operates a butterfly

> valve and the slide's drawn up by vacuum. those

> are kinda cool i guess on 4 strokes, for smooth

> operators. That's what grimm is thinking of

Ahh okay I thought by diaphragm people meant that scooters used pumper type carbs. I had a 50cc crotch rocket that basically had a little backpack blower engine and used a little chainsaw/weedwhacker Walbro pumper carb. I love my peds but I miss that thing, had a hell of a gearbox on it and you could pull wheelies standing on the footpegs and shit like a sportbike


Re: Diaphragm Type Carbs?

Never seen one with a gear box except a reduction box or a dual variated 'box'. Was yours actually a gear shifting unit?

Re: Diaphragm Type Carbs?

Flagrant - Wrote:


> Never seen one with a gear box except a reduction

> box or a dual variated 'box'. Was yours actually

> a gear shifting unit?

Not actual shifter box, it had a CVT. Which I think was the dual variated you are talking about

Re: Diaphragm Type Carbs?


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