I have a 14 M8 with about 1200 miles and at around 800 miles I started noticing that it didn't hold RPMs like it used to. Its not terrible but its not great either... whenever the sled has to work a little bit it will drop down somewhere around 7900rpms or so and it will take a while for it to regain full rpms. I read a thread similar to this earlier this spring on here and nobody really knew the cause most people were blaming clutching but couldn't find anything wrong with their clutches. I have recently heard some guys saying that it is because there is slop in the piston due to not being broke in properly. Iv been told if I put new rings in each piston problem is solved. I don't know anyone who has time to ride there brand new sled 200 miles like a grandma to break it in. I Guess all im asking is if anyone else has found anything or heard anything else about this problem or the new rings or anything about it.
14 M8000 not holding RPM after 800 miles. Piston slop?
- Thread starter brodCatMan
- Start date
Sounds like hot a hot clutch too me. If you do not pay attention to your belt deflection, this can be a reoccurring issue.
There will be a tendancy for your belt to slip in the secondary if the deflection is too much. I like to run my belt just above the top of the secondary. If you adjust it too tight you will know as the belt will squeal at idle and then just remove a 0.030 shim from shim pack and you will be golden.
There will be a tendancy for your belt to slip in the secondary if the deflection is too much. I like to run my belt just above the top of the secondary. If you adjust it too tight you will know as the belt will squeal at idle and then just remove a 0.030 shim from shim pack and you will be golden.
I doubt it's engine related with only 1200 miles. How many miles on your belt? An old belt with lots of miles on it can loose RPM and there is nothing you can do but replace it. Check for binding clutches with the springs out and replace the springs. They take a set and lose force after a while.
If there is anyone you know with the same sled that does pull rpm, swap the secondary with them and I'll bet the rpm comes back. Clean clutches as well and put in a new primary spring.
Hey , My sled comes appart after every ride. Something you should maybe check is the cylinder walls. just pull the panels and hood assembly off then start by taking the springs off. I like to use a piece of nylon string. Then look into the ypipe, you will need a flash light. Shine it in towards the pistons... if they have shape vertical lines scratched in them well you sleds top end will need to be replaced. If this is not the case then, like everyone else said its probably in your clutching. I have heard of guys struggling to pull RPMS and it was because they had broken rollers in their secondary. Check the clutches and report back.
Thanks for the feedback guys. Once we get more snow ill see if I can figure out the problem and let you know if I find it. Hoping that the rumor I heard about new rings is just that, a rumor.
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Bacon
Well-known member
I'll tell you how to properly break in a new sled. Make sure you warm it up good. Take it easy for a half mile or so so everything is warmed up. Then ride the living $hit out of it. I don't know who comes up with this take it easy to break in a motor crap. You need heat and load to properly seat the rings and break in the motor. It's how I run all my new sleds and they all seem to run strong. Replace clutch springs and belt. That should fix your clutching. If not, you might have rollers or bushings out of spec. When replacing springs, make sure to inspect and clean the clutches good.
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arctic2009
Well-known member
Look at your clutches.. Clean them and check springs etc. there's no way your sled has run 800 miles if the top end isn't properly broke in.. The 800 motors are pretty much bullet proof.. That whole piston slop thing is a Polaris problem lol
Do a compression check then you can stop worrying about the top end. As others have said it is most likely the clutching or belt.
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Kbakbmr
Active member
Mine did this too, put a polaris black green 120-340 in the primary and when i hammer down it hits peak rpm and holds it. Springs are a big deal, my buddy's a factory cross country racer and he said they change springs every race because they lose some poundage. Imagine putting 1000 miles on stock springs.
Its common to change springs but the real issue is still in the secondary. What ever cat did in 14 helped with the belt problem but made the rpm a bigger problem.
I'm having 2 clutches cut by MVMS and we will see pretty soon if that was my problem but so far I know of 6 secondary's on 14's that where replaced for this reason and it fixed it.
I'm having 2 clutches cut by MVMS and we will see pretty soon if that was my problem but so far I know of 6 secondary's on 14's that where replaced for this reason and it fixed it.
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Bacon
Well-known member
Getting the secondary cut makes a huge difference with the clutch efficiency. I won't run without it it makes that much difference in getting consistent rpm. I think Cat knows the secondary is an issue, but they want to ignore it. Rumor is that we will have team secondaries next year on the Cat. Don't know if that's good or bad. For all the crap that Cat gets for their clutching, once you do a couple things to them they seem to work real good.
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suitcase
Well-known member
What do you mean by, getting the secondary cut ? Im new to cat last year.
We did work to the primary on the polaris , but what can be done to the secondary ?
So what did you see out of the box that made it junk?
They machine the sheaves to the correct angle so The primary, secondary, and belt all match.
When it's down 400 rpm compared to the same 15 next to you in pow, then you swap secondaries and it backshifts and pulls the same rpm as that 15, then you know the clutch is junk. Got it warrantied and rode it today with a new secondary and all is good. Pulled same rpm next to the other 15.
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