tomos clutch tuning!

kim jensen /

OK, so just how does the Tomos clutch on an A35 work? I heard conflicting info on what/when the first gear releases and 2nd engages.

Background: 64cc Polini 4 reed block, MLM pipe and clutches reshoed with brake material.

I have tried various spring and fluid combinations but it still won't shift worth a damn!

So the question is: does the first gear need to stay engaged at high rpm for the 2nd to engage and then does first gear stay engaged the entire time 2nd is engaged? Or does first need to release for 2nd to engage?

Thus is where the conflicting info is. The manual is also unclear.

I have tried red /yellow, red /blue, and yellow/blue for spring setups and 0-20 synthetic as well as type F trans fluid.

So if u hammer it of the line and then let off, it may shift, otherwise not so much.

So keep in mind the non original, not cork clutch shoes, do I need the first gear to stay engaged longer for it to shift (weaker spring ) or less stiffer spring?

As always, thanks for your input guys!

Re: tomos clutch tuning!

First gear has to be engaged for the second gear to engage.

What you have to understand is that the clutches and the gears are two different things. The first gear is attached to the first gear clutch bell and the second gear is attached to the second gear clutch. The only thing that starts the second gear clutch spinning is parasitic drag on the first gear drum shaft. Until the second gear shoes come into contact with the bell the second gear just floats waiting for enough speed to engage. This design makes second gear nearly untunable. Depending on how much drag there is on the second gear clutch, it will engage sooner or later in the rpm band. So in other words, totally random engagement.

It is possible to short-circuit second gear by putting too light springs in the second gear clutch. What would then happen is second gear would engage immediately when the first gear clutch fully engaged.

Re: tomos clutch tuning!

kim jensen /

OK so first gear needs to stay engaged for 2nd to do so. Would a weaker than blue spring , like a stock spring , help?

Re: tomos clutch tuning!

the second gear clutch is spun by the transmission gears. If you push the bike down a hill fast enough the second gear will grab and turn over the engine- it is independent of the first gear clutch. There is a one way bearing (the roller clutch) that lets the first gear set spin when it is in second gear. It works like a sprag clutch, the clip tensions the rollers.

since the second gear clutch is spun by the transmission, you can put stiffer springs in it, and also lower the chain ratio--- with a smaller rear sprocket, the rear wheel will need to be spinning faster for the second gear clutch to engage.

Re: tomos clutch tuning!

kim jensen /

Thanks guys!

OK, so first dies always stay engaged, even after 2nd has taken over.

I think my rear sprocket is already pretty small, so high trans rpm's are needed for 2nd to engage. What I would like is for 2nd to engage sooner. Would a weaker than blue spring help? I have to take off like a bat out of hell, then let off the throttle to get it to shift now. And it often doesn't. Sometimes if I motor along slowly it may shift into 2nd at around 22-24 mph. I usually find myself coasting and having to rev the crap out of it to get it to change. Would going from yellow to blue spring on first and then a stock spring on 2nd be worth trying, or is that going the wrong direction?

Re: tomos clutch tuning!

You may have too much oil in the transmission

Re: tomos clutch tuning!

put a sock spring on the second gear clutch. The stiffer of the stock springs. I think a35 came with both gears stiffer stock spring.

Re: tomos clutch tuning!

Overpriced Parts /

Ya nothing like a za50 basically it's untunable's far as I'm concerned compared to a za50. I can make za50 feel like it's a three speed, make it shift into 2nd at near 40mph, I could make it have a full and part throttle kickdown like an auto transmission car and downshift when bombing corners I can't do that without tomos engine it's stuck in second gear until your practically stopped and shifts sooo early.

A tomos engine is best just modified stock with a performance pipe or maybe just a mild kit.

Because of the low shift point I mod a tomos engine to have low-end power.

Estroil and circuit pipes with small carbs work the best.

Re: tomos clutch tuning!

kim jensen /

Well good to know. I'll try and round up a stock spring.

Well I can't go back there Ken. Its a polini 4reed with 21 phbg & MLM pipe. Nothing mild about it! (:-)

Re: tomos clutch tuning!

Overpriced Parts /

kim jensen Wrote:

-------------------------------------------------------

> Well good to know. I'll try and round up a stock

> spring.

> Well I can't go back there Ken. Its a polini 4reed

> with 21 phbg & MLM pipe. Nothing mild about it!

> (:-)

You Still can run a estroil pipe tho

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account