PING: MotoRandy

[Yager200i]

MotoRandy,

In another area of KymcoForum.com, you suggest shaving a bit of length off the drive pulley boss to get a higher gear ratio.

Have you done this?

What was the effect?

How much to shave off?

How to shave it off?

Would the metal of the drive boss survive a lathe alright, or is something more gentle like a belt sander in order?

Thanks for any info.

[MotoRandy123]

Well I made some mods to mine but just modified the ramps and the front of the pulley.
The boss is hard and needs to be square and flat so I'd machine it or use a sanding belt.
I'll see if I can find those pictures or what I did. My scoot would only do 60 so I was looking
to get little more top end. Later I could do 70 but I'm not sure if it was the mods or just normal
break in...

[MotoRandy123]

Ramps

[MotoRandy123]

More Ramps

[MotoRandy123]

Rear Pulley Slots

[Yager200i]

For the rear pulley slot, what does extending that slot do?

For that matter, what does that slot do? Why is it slanted?

[az_slynch]

For the rear pulley slot, what does extending that slot do?

Extending the slot will theoretically allow the sliding sheave of the driven clutch to open up further and allow a greater overdrive ratio when the CVT is fully variated. Of course, this relies on having a variator that can lift the belt enough to pull it all the way down out back and having a contra spring that can compress that far and not go into coil bind.

For that matter, what does that slot do? Why is it slanted?

The slot holds the guide pins/rollers and keeps the fixed sheave and sliding sheave turning together The slant causes the sheaves to rotate slightly in respect to one another while variating to help regulate the rate at which the transmission variates. The more vertical the slot, the quicker the variation occurs. Steeper slots slow the speed of variation, but help keep the CVT in high gear when minor changes in engine speed occur. 

[MotoRandy123]

I'd say not much gained from the rear slots. The ramps made a bigger difference...