850 power fade like 800?

On my 800 etec i used an aftermarket thermostat to prevent the power fade that happened when you did long wot pulls. Does the 850 have the same problem?

Johnny Hurkot made the proto fade last year at Kusters but then I get fade just watching vids of him ride. Lol.

I did not get any fade on the production 850s. I think you will see a slight rpm drop with hot clutches, maybe down to 7500. The ones I rode did have all the heat shields and foam removed so I'm sure that doesn't hurt.

Let's hope the Power Fade days are behind us. You need to be on the ball to correct a Power Fade!

These problems were first documented with the Summit Highmark. Back in the day it was the owners in the West like Lund and many others who figured it out through experience. They were not told why this happened and they were forced to figure it out for themselves. Owners like Lund pioneered over a decade ago the kind of information we have today on forums. Unlike the 800s, the Summit 1Ks would fall flat from running too cool. That is irony.

I did not experience any power fade on long pulls on my 850 however I do not do the super chutes like the crazy young kids.

Usually on long pulls you get lot of heat buildup on the clutches which transferred to the belt is typically a bigger power robber and cause of waverying rpm.
A rotax will spin happily at its max rpm for anything I have seen - clutch heat dissipation is usually the challenging area to work on.

Keep as much air flowing as possible past the clutches - vent behind the A-arm directly in front of the clutches. Even more important is venting at the back and top of the panel to let as much air out as possible.

850 is fade free or at least I can not ride the sled to that point!

I heard of no Power Fade in the East either - on and off trail - so that's a good sign. We get the Power Fade on the 800s a lot just trail riding, but along the St-Lawrence Low Lands many of our trail system are close to Sea Level so it's full on power. We have an 800 that has started doing this more and more as the season progressed, which is a pain. It's the last problem that I want to deal with and I think that's one reason why the 850 has pretty much taken over all the 800s with the exception of two low sales models. What can I say, I am hopeful this problem disappears for good. Only the 600 HOE do it now. I wonder if they will eventually get a revamped engine.


"clutch heat dissipation is usually the challenging area to work on."

I was perusing some old BRP documentation and you pretty much paraphrased what they were saying. It is an ongoing battle.

Yeah I'm a fan of adding additional venting and will be doing so on the 2018. Pull all foam, may drill some holes in clutch cover too. Hopefully I have good luck with it.