4-stroke Clutch Balancing

justinkredible56 · Oct 13, 2011

Has anyone ever had to balance the primary clutch on their apex/nytro? I've been fighting belt burning issues since I first bought my nytro and was wondering if the primary clutch possibly needed balanced.

I've gone through probably 10-12 (not an exaggeration) belts and my sled has 2000 miles on it. I've done a LOT of preventative maintenance on this sled to help aid my issue but I'm wondering if balancing my primary may need to find it's way onto the list.

Any input is appreciated!
-Justin

pelon · Oct 14, 2011

Holy crap you got a problem!!

I' ve had my apex since December of 2006 and have not burned a belt yet (almost 3000 miles). Just changed them out occasionally for maintenance.

I have not balanced mine, as I think their pretty close from the factory. Thats not to say yours is not screwed up. I would check your alignment also.

Thistledoo · Oct 14, 2011

from what we have seen in our group is the apex and nytro are different animals. Apexs dont use belts and the nytros can more regularly...thats for sure.

but not boosted should be easier on belts

justinkredible56 · Oct 14, 2011

pelon said:
Holy crap you got a problem!!

I' ve had my apex since December of 2006 and have not burned a belt yet (almost 3000 miles). Just changed them out occasionally for maintenance.

I have not balanced mine, as I think their pretty close from the factory. Thats not to say yours is not screwed up. I would check your alignment also.

Ya I haven't the slightest clue why I'm having such a problem so I'm trying to cover all bases. I confirmed alignment last season the only thing I haven't done is balance the primary.

ruffryder · Oct 14, 2011

I wouldn't think it is a balance issue, as the crank is very heavy compared to other motors, like 2 strokes.

What is your gearing, track, and clutch setup?

What does your clutch sheaths look like? When is the last time you took your clutches apart and cleaned / inspected them?

justinkredible56 · Oct 14, 2011

ruffryder said:
I wouldn't think it is a balance issue, as the crank is very heavy compared to other motors, like 2 strokes.

What is your gearing, track, and clutch setup?

What does your clutch sheaths look like? When is the last time you took your clutches apart and cleaned / inspected them?

As far as clutching goes I've tried everything under the sun and had a thread about it a while ago and received a lot of helpful info.

I'm running out of things to check but balance was one of them. Just wondering if anyone has ever had/needed to balance their clutch on the 4 stroke Yamahas.

Pro116 · Oct 14, 2011

14.5 rollers will really grab the beldt harder and you won't get so much slippage plus it will have a smoother engagement.

justinkredible56 · Oct 14, 2011

Pro116 said:
14.5 rollers will really grab the beldt harder and you won't get so much slippage plus it will have a smoother engagement.

Yup I'm currently running the 14.5 rollers, I've played with the clutching enough that I don't think it's the cause. Just wondering if ANYONE has ever had to balance their primary or heard of anyone else having to do it.

kinger9 · Oct 14, 2011

I have NEVER heard of anyone having to balance the primary clutch. Belts fail from heat, have you ran the sled and used a infared heat gun to measure the temps? Have you checked your motor mounts? Its either out of alignment static or under load, or the secondary and primary are not agreeing on the clutching you used.

justinkredible56 · Oct 14, 2011

kinger9 said:
I have NEVER heard of anyone having to balance the primary clutch. Belts fail from heat, have you ran the sled and used a infared heat gun to measure the temps? Have you checked your motor mounts? Its either out of alignment static or under load, or the secondary and primary are not agreeing on the clutching you used.

I haven't used a infrared thermometer on the clutches.

Sled has done it from day one. I think I went through my first belt around 300 miles. I checked the motor mounts this summer and they aren't broken.

Primary and Secondary are aligned within spec at rest (static), I would assume if the primary is balanced that this wouldn't change during regular operation.

Good to know that you have never heard of someone who's primary was out of balance on these 4-strokes. I'll check that possibility off my list and continue working in specific areas that could potentially be the cause of my problem.

As for clutching I had a big thread going on a while back that addressed all of this. It included all of the details and even included pictures of primary and secondary ride height. I clean my clutch faces after every ride, I properly break in my belts, and wash my belts before I slap them on my sled.

I went through my sled with a fine tooth comb and examined any possible troublesome areas that may be contributing to my short belt life and have tried to address them all this summer. We will see how it pans out! ---Cross your fingers!
-Justin

kinger9 · Oct 14, 2011

That must be really frustrating sounds like you have been through everything. I would get a infared temp gun and take some measurements after long pulls, high loads and see what it is, then have a buddy do the same to compare. Have you tried a different belt other then the 8DN yammie belt? If you haven't yet once you get the gun it might be neat to compare.

I suck at clutching and outsourced that to a shop and never blew a belt since then. They found really high temps in the old clutching set up and it was blowing belts bad, after they got it cooled down I change belts just as PM's.

Good luck bud.

justinkredible56 · Oct 14, 2011

kinger9 said:
That must be really frustrating sounds like you have been through everything. I would get a infared temp gun and take some measurements after long pulls, high loads and see what it is, then have a buddy do the same to compare. Have you tried a different belt other then the 8DN yammie belt? If you haven't yet once you get the gun it might be neat to compare.

I suck at clutching and outsourced that to a shop and never blew a belt since then. They found really high temps in the old clutching set up and it was blowing belts bad, after they got it cooled down I change belts just as PM's.

Good luck bud.

Only ever used the Yamaha belt. As far as outsourcing your clutch work to a shop, I've been down that road also. I ran Hartman Inc's custom clutching setup for my weight, track length, gearing, elevation, and riding style...all giving me the same results.

I think a temp gun might be beneficial to try out, at least that way I'll know for sure max temps for each clutching setup.

This year I've dropped down another tooth in the chaincase and I'm running a 18t top sprocket. Also deleted the headlight and modified my instrument panel and replaced with some heavy duty screening to allow more airflow throughout the engine compartment.

Maybe I'll wire up a computer fan to my clutch guard

Any ideas on how to do this are appreciated haha

twincam88 · Oct 15, 2011

proper break in take it easy for about 50-60 miles no WOT runs. scuff your clutches with scotch brite and why not have a scotch while your doing this lol!! are you vented? check your panel below the primary for tears. the panel likes to get pushed up into the clutch and tear a hole in it then snow gets in there. are the belts gernading or just threading out? there are guys around here with 2500 km on a belt with boost.

Polarisrocks · Oct 15, 2011

I would put back in the 15.5 rollers, I know a many guys who lost track speed by running the 14.5's. How does the bottum of your seconday look? does it have any rough spots ? what springs? what weights? Do your clutches move freely and smoothy without springs in them? Do they move freely when they are warm/hot? You could be haaving a clearance issue, Can you would see which one is hotter

justinkredible56 · Oct 15, 2011

I was trying to keep this thread off clutching but the members here are just too eager to help!

Thank you everyone who has replied to this thread so far!

Here is a link to my old thread if you want to know everything I've done regarding clutching-

http://www.snowestonline.com/forum/showthread.php?t=247159

Here is a link to my current build thread where you can see what venting I'm doing this year-

http://www.snowestonline.com/forum/showthread.php?t=273866

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4-stroke Clutch Balancing

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