08 DRX 90 H20, moter fine, seems stuck in high gear?

[KDX Dad]

Thanks again for all the help I've received here, but issues still on going.

Got motor done just before leaving for a national Friday afternoon. Did some brief yard running after break-in, all seemed good.

During first lap quad would not move (on its own) AND would not rev past a few k rpm. Once kid got going, read pushed by other parents, it would go till he slowed down and end up stuck again.

My first thought was that the variator was keeping in a higher range, not allowing the motor to rev and not enough torque to start my kid from a stop. Cooling down did improve the situation and with breaks he ended up eeking out 5 laps on a nearly 2 mile course.

Got the bike home and just did the tear down of the CVT. Here's what I found:

Visually, belt looked good. Bell housing looked like it def heated up bad (understandable 10 miles like it was running).

variator wide open, clutch fully closed.

Started motor (cold) after short warm up, variator and clutch cycled properly, variator opened and closed smoothly, clutch engaged.

Had a friend hold the tire and presto, he was able to hold the wheels locked, and the motor would not rev past a few k's rpms again, totally replicating the problem. Clutch was slipping for sure.

At this point I dismantled the clutch, no belt, ran it again, motor spools up nicely, full rpms.

So the clutch bell is burnt, clutch arms look decent, I'd say about .030-.060 worth of pad left on them, didn't seem overly glazed.

So is my issue as simple as new clutch parts?

Also, the fact that I couldn't just rev out the motor troubles me a bit. I confess I'm not all that comfortable with this CVT concept and prolly am missing something as to the reason why the clutch didn't just keep slipping, allowing the motor to rev out. It's still nagging me that it's a variator issue, gearing issue.

So thats what I need help with. I got a lot of assistance from here after the massive water ingestion and I can say if I ever run into one of you guy at a track some where, I don't care how far away my rv is, I will send my girl friend to get you an ice cold beer!

[jerkyboy]

Need clutch info

What variator
Weight of rollers
what clutch
clutch springs
torque spring and brand
sprocket sizes

[KDX Dad]

I'll give you what I can. variator stock and original. Torque spring is white, I think 1500 stall.

Weights are copper in color I believe. Clutch is stock.

I sort of pieced things together based on what I could afford at the time to change from the factory, it may have only been the torque spring back then.

Hope this helps.

[KDX Dad]

Sorry primary is 19 and the rear, not sure but will run out right now.

This is sort of what I was going to get into to set this up right, gearing wise.

[KDX Dad]

That be 19t 31t

[travis rimmer]

sounds like a torque spring issue if u have not changed it in awhile thats probaly it not sure if u said motor size but i think the 50 guys use a 1000 rpm spring and the 90 guys are running 1500 springs check the washer inside the variator make sure its clean and all other parts check ur roller weight to got to know that

[KDX Dad]

Thanks Travis,

The spring is a 1500. It's also only got a couple of races on it but that could be it. I will replace it for sure but really would like to understand why the motor wouldn't rev up.

Also someone please let me know what set up I should be running.

Hare scramble - 120 lb rider - currently 19x31 gearing.

Need to know what weights and spring combo.

Thanks,

KDX Dad

[Logan #34's Dad]

With a stock variator you should be around 4.0 gram weights (6 of them) with a 1500 spring. You are saying that it won't rev while on the ground right? If it rev's up but you can hold it back from going forward your tranny gears could be slipping. They are pressed pieces and can spin inside themselves.
Also sounds like your clutch may be the wrong size for the bell. Clutches can be 105mm or 107mm and your bell may be a 109mm bell for a 109mm clutch. In other words, your clutch shoes have to open too far to hit the bell causing it to slip.
It sounds like a clutching issue though. See what the rollers weigh and replace your torque spring with a new one and play with the roller weight. I'll bet your way too high in weight.

[fomospede]

i have to ad if it is noticable that your bell got hot it is also probly trash! and will cause problems as you have explained as it heats up

[poppy]

check piston to wall clearance

[KDX Dad]

Fomospeed thanks, and ya bell is blue. I really think for what ever reason it's hitting high gear too soon, or dropping right to high on the pulley right away, leading to the clutch slipping.

So I will order new clutch, variator, bell, torque spring, clutch pad springs, roller weights.

Working that out now with Gforce, found I have a 9 to 1 tranny ratio, 18" tires, plus got a 19t x 31t gearing.

I hope amongst this things I will solve it. Atleast get it set up properly.

As far as the piston size goes, it's good. Was tight as all get out, maybe a .002-.003 clearance. Tell me if that is where I want it too be. Motor runs nice disconnected, and I know it's with little load but I can't see that being the issue when the clutch is obviously so messed up.

Thanks,

KDX Dad

[RCR_531]

I am having the same problem on an AC 90 quad. I have tryed to different torque springs and different weights. Check exhaust for blockage and a spare CDI. Let us know if you find out anything. Thanks

[3400ben]

We run a 1000 t spring and 4.5 rollers in are 90 ( stock ) for xc

[Hetrick Racing]

The cvt system is tuned with two specific parts roller weights and spring tension.
There are many variables that play into your tuning though, ramp angle, compressed spring tension, belt length, belt width, belt angle, as well as stall speed, bushing length, bushing tolerance, and well much more
Give us a call we can help tune it on the phone although if you’re not that far away the cvt tuning seminar would help you more than anything you may do.

I posted this yesterday on another topic but it stands firm,also in this case I would want to add if your quad has an engine performance issue many times it will be mistaken for a clutch problem.
If you have not figured it out feel free to give me a ring.

Rich

[KDX Dad]

Hey Rich,

Thanks for the response....We've been so busy with the end of our series and other sports I didnt get much chance to come back here.

But I did want to tell you that you have a fine outfit there in PA. I stop in from time to time and many times I'm on the phone with Chris (think I got the name right) looking for parts for my sons DRR (recently did a top end with parts from Hetrick). I can say Chris has always been there to help and after talking with him about straightening out my latest CVT problem, I can say you guys were the most helpful and knowledgable. Just wanted to say thanks!

I will look into that CVT seminar but my kid is moving to the 13-15 class and thinking of a shifter 125cc now.

Thanks again!