CVT tuning thread

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beltbuckle

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Aug 22, 2011
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Thought I would start a new thread on CVT tuning/tweaking.

I have a predator 99cc, with comet TAV2 30 series clone CVT, with a 7" driven. 10t sprocket on the CVT and a 56t rear sprocket on the rear wheel.

Right now I'm fine with the performance but am wondering if I can get a bit more out of it. Acceleration from a stop is good, and it tops out around 30 MPH at only 2800 RPMs.

Basically I am wondering if there is a way to tweak the CVT to stay out of "high" longer? I'd like to get the RPMs higher so I'm more into the power curve of this motor.

I know there are different springs and spring pre-loading holes but wanted to get some input from those with more experience tuning these things.
 
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JonnyR

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May 13, 2012
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i have read a few threads on these and they sometimes rob RPM without a heavy spring to try to keep it from going strait to high with all the power these engines make you have to force them to stay im there power band.
also did you take the governor off?
 
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beltbuckle

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Aug 22, 2011
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Yeah governor has been removed.

So sounds like first thing I'll try is to move the driven spring from dedault hole #2 to hole #3 for more pre-load tension.
 
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bowljoman

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Aug 7, 2010
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beltbuckle said:
Yeah governor has been removed.

So sounds like first thing I'll try is to move the driven spring from dedault hole #2 to hole #3 for more pre-load tension.
Click to expand...
The typical way to adjust the driven without getting a harder spring is to add a washer or two between the spring and the pulley.
 
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young grease monkey

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Sep 20, 2011
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what happens is that the drive pulley closes more the higher the rpm till the other pulley can't widen any more and it binds up. you need to put shims in the drive pulley to limit how much it can close.
 
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curtisfox

Well-Known Member
Dec 29, 2008
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Intresting I better watch this and see what the cure is. Don't have one yet but thinking on it...............Curt
 
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young grease monkey

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Sep 20, 2011
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what i'm saying is that you should limit the travel of the drive pulley ratio so it can't over tighten the belt and bind at high rpm. a stiffer spring would definetly help, too. you want it to have a constant rpm of about 4k, 5 if you are racing.
 
Gbrebes

Gbrebes

Well-Known Member
Jul 16, 2010
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Scotto, would you happen to have a source for these stiffer garter springs you speak of? Also, when you used the comet-type clutch, did you ever buy a stiffer spring for the driven clutch? the yellow/green combo looks to be the stiffest, but there are a lot of options. Just wondering if you had some knowledge.

Thanks,
Gilbert

scotto- said:
The very first thing you wanna do is get stiffer garter springs for the driver pulley. then you take it from there. ;)

dnut
Click to expand...
 
wayne z

wayne z

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Dec 5, 2010
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I don't know if it has already been mentioned here yet, but the chinese mo-ped (dunno why they"re call mo-peds, no pedals) scooters use a short bushing between the driven sheaves so they can't close all the way, to keep the ratio from going too tall and allowing the little 50cc motors to rev higher.
If you find that your overall ratio turns out to tall, this can be an easy mod.
 
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