RPM Fade-Another POV

[Lenn Johnson]

I have a theory:
There's a thread going about a new 800 with an out of phase crank. Dead After .1 mile
This was a very common problem with 3 cylinder engines back in the day. This got me thinking....... I'm wondering if Axys sleds with fade issues are experiencing the same thing. Has anyone who's chased this issue checked their cranks for proper phasing? I didn't. Here's some information to digest:
I've had 3 Polaris sleds in a row have issues with fade. My 2012, 2016, and now my 2017 Assault. All were studded from day one...except my current Assault.
I was around 22-24 hours on the my Assault when I experienced a sudden decrease in power. I was riding from a valley up into a ridgeline and the outside ambient temps where also falling fast. As the air got colder, my sled began performing better. As the snow got firmer with altitude/cold air, my Assault was hooking up great. I had just studded my track the day before AND installed 10-68 weights because it was over reving to 8550. The 10-68 weights brought down my rpms to 8350 and my sled was an absolute animal...fastest stock sled I've ever been on. I had been seeing speeds of 116 unstudded the weekend before.
Then suddenly as the snow became firmer and traction increased, I experienced power fade in the very next corner. For the rest of the day, my sled would not rev past 8000 rpm. The next day I installed the stock weights and changed the belt, then went for a ride. Better...pulling 8150 but not the same animal I was on the day before. I'm 6 ft and weigh over 260 with gear. Is it possible that I may have twisted my crank out of phase a bit? These cranks are pressed together just as they were back in the triple days. So it's possible that with too much traction/power, that we could be twisting the crank a bit. Especially heavier guys like myself. Think about it...let's hear your comments. I'm going to be checking my crank phasing next, just not sure how to do it properly.
__________________

 

[ZR SLEDHEAD]

Back in the ZR 800/900 days, very common to see one out of phase if it had spit a belt out, odd one it just happened to.
So yes, you never know unless it's checked.

 

[Brock]

This thing u guys are calling fade is loss of rpm.

Check a combination of things

valves.
Check the travel ,clean and inspect ,check exhaust valve actuator, push and pull cable to see if it moves freely

Throttle
Check to make sure it's 0.010"-0.029", if it's to much free play it will cause running issues . Excessive free play can cause release switch to stick and stall engine

Cvt system
This is the major cause of rpm loss ., belt slips up high in primary causing rpm loss cause of glazed belt, dirty sheaves, to light of primary tip weight to pinch belt up Top (10-66's), 10 series doesn't have enough tip weight , primary spider to tower clearance is over 0.004".

Exhaust leaks
Huge in power loss. Won't let sled rev when y pipe leaks at motor, need to take y pipe off and make sure it's perfectly flat(most aren't) and put a slp y pipe gasket on and torque bolts with blue loc tite. Check round graffol seals and replace . If any oil in belly pan is present , you have leaks.

Check wiring and resistances on things

 

[Dr.Notadoo]

crank phasing would change all the port timing and would always be like that until corrected would not come and go.. most of the issues people have is all related to the cvt and just general running strategy that we cant control. Your dealing with variables that change in seconds, computer makes calculations and executes outputs.