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2020 KQ 750
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Discussion Starter · #1 ·
Hi all,

Just got the Coop Mod #3 done and a yellow spring for my son's Vinson. Question is, when I put it back together, the belt rides up enough on the secondary to actually prevent it from getting in the case. I don't see any way to spread the secondary using a case bolt like or anything of the like, and I'm thinking the new stiffer spring is just keeping it closed up real tight? I used a mallet to seat it enough to get it in and on but there is still a slight belt rub. I put it back together and thought that firing it up and "cycling it" as it were would reset it. All works fine, but after it settles down the belt still rides high, but not enough you can't move it by hand. Ordered a new Dayco belt for a little insurance, but I've thrown around grinding the case slightly where it rubs, as it looks like there's plenty of material, or do they make a "thinner" belt than the OE? Is a tiny rub to the top belt surface that deadly? I'll try to get a pic, but it's a MM or so we're talking, or is this normal with a stiffer secondary? Test rode it around and no ill effects, as it just slightly rubs when slowing to a stop. Researched ad nauseam and found a decent amount about belt rubbing with Polaris and Yamaha, but no Suzuki. Son's hounding me about it and we've got a 3-day ride 4 hours away coming up next week, so any help is greatly appreciated!!

P.S. Coop Mod #3 was welllll worth the money!!!
 

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The spring is not at fault, it just provides the belt's tension. It's the Coop 3 mod that makes the belt run lower in the front sheaves at full reduction and as the belt is a fixed length, it's gonna ride higher in the back because of that. If it rubs on the casing as a result of that then the mod was a bit too much for that application. If careful sanding or grinding of the interfering spots fixes things then well and good.

You can't 'spread the secondary' to make the belt go lower. That's thinking about it backwards. The front clutch uses the amount of belt it needs at a given stage and the secondary clutch, spring loaded as it is, closes on the belt that the front clutch leaves it. If you forced the secondary open to try to get the belt lower, it would slip like a son of a bitch! The rear clutch is the front clutches bitch, whatever the front clutch does it does the opposite, the rear clutch makes a circle out of what the front clutch leaves it.
 

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2020 KQ 750
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Discussion Starter · #4 ·
Ahhh I see said the blind man as he picked up his hammer and saw. Thanks for the info, I honestly never really knew exactly how the CVT functioned, but after reading this I've definitely got a much better idea! The mod was done by Coop and I don't honestly know how much was taken off. Tonight we pulled it back apart and actually looks like it was just barely rubbing against the gasket, and so minor that you can see where its touched but can't feel anything with your fingernail and didn't even scuff the print all the way through. I could spin it by hand no problem so we closed it up and he rode it for a bit before we pulled it back apart and didn't see evidence of any further contact so we went ahead and buttoned it all back up. Thanks for the reply, I really appreciate it!
 

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Arnie does good work, no question about it. The machined plate mod is the best bang for the buck, that actually has no downside. You get better launch, better low speed tractability and control and you don't sacrifice anything for that. No change in top speed or high speed behavior. I bet you are good to go now.
I left out that the stronger spring actually does provide enhanced backshifting and engine braking as well as a stronger grab for the smaller contact patch of a Coop3 type modified sheave. Happy wheeling. :)
 
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