2021 Assault with 2" track - Over Rev issue!

[Al - 850 Matryx]

Hi Guys/ Gals,

I'm new here, sno-checked a 2021 Assault 850 with a 2" track. I now have 25hrs. and about 600 miles. The sled is overrevving at WOT. I can't get more than 95-98 mph. I'm not trying to lake run but it seems slow! The engine cuts out once i over rev, then allows to pull again once the rpms drop below 7000. I've brought it to the dealer twice now (picking it up in 2 hrs for the second time) dealer says the track is rated for no more than 80-90 mphs??? It still doesn't explain the over revs at WOT. Wondering if anyone else is having similar issues? Whats your top end and what are you reving at?

Thanks,

 

[SquirrelyJam]

Hi Guys/ Gals,

I'm new here, sno-checked a 2021 Assault 850 with a 2" track. I now have 25hrs. and about 600 miles. The sled is overrevving at WOT. I can't get more than 95-98 mph. I'm not trying to lake run but it seems slow! The engine cuts out once i over rev, then allows to pull again once the rpms drop below 7000. I've brought it to the dealer twice now (picking it up in 2 hrs for the second time) dealer says the track is rated for no more than 80-90 mphs??? It still doesn't explain the over revs at WOT. Wondering if anyone else is having similar issues? Whats your top end and what are you reving at?

Thanks,

What's your RPM hitting? There's all kinds of gear ratio and theoretical max speed information available in the various forums. It seems common that the 850s will hit 8400-8500 RPM and require heavier weights in the primary to bring that down to the ideal ~8100 RPM.

 

[TurboJamie]

That's about all the gear you have in it with a 2" track. My GF has the 2" track and her's is geared around 95 mph. Mph 1.5" track sled is a good 10-15 mph faster.

IF your over revving and don't feel its out of gear an Ultimax XS 811 belt will lower your rpm about 250-300 RPM.

 

[Al - 850 Matryx]

What's your RPM hitting? There's all kinds of gear ratio and theoretical max speed information available in the various forums. It seems common that the 850s will hit 8400-8500 RPM and require heavier weights in the primary to bring that down to the ideal ~8100 RPM.

My RPM's are hitting 8600 - 8800, I'm getting there around fast. It's like i'm hitting the rev limiter way too fast. The dealer said today that I'm running out of gear, ok, possible. But it still shouldn't be setup to over rev that easily and that much. Then goes on to tell me not to got WOT unless i'm in 2-3ft of snow. This doesn't make sense. Weights would probably help or gearing, I'm just worried of voiding the warranty.

 

[Al - 850 Matryx]

That's about all the gear you have in it with a 2" track. My GF has the 2" track and her's is geared around 95 mph. Mph 1.5" track sled is a good 10-15 mph faster.

IF your over revving and don't feel its out of gear an Ultimax XS 811 belt will lower your rpm about 250-300 RPM.

Do you know why that belt drops the RPM? I'm ok with that speed if that's what it's meant for but it shouldn't hit the rev limit every time i have it WOT. does hers hit the rev limit at 95mph?

 

[Al - 850 Matryx]

My RPM's are hitting 8600 - 8800, I'm getting there around fast. It's like i'm hitting the rev limiter way too fast. The dealer said today that I'm running out of gear, ok, possible. But it still shouldn't be setup to over rev that easily and that much. Then goes on to tell me not to got WOT unless i'm in 2-3ft of snow. This doesn't make sense. Weights would probably help or gearing, I'm just worried of voiding the warranty.

I appreciate the feedback!!

 

[Al - 850 Matryx]

Do you know why that belt drops the RPM? I'm ok with that speed if that's what it's meant for but it shouldn't hit the rev limit every time i have it WOT. does hers hit the rev limit at 95mph?

I appreciate the feedback!!

 

[SquirrelyJam]

My RPM's are hitting 8600 - 8800, I'm getting there around fast. It's like i'm hitting the rev limiter way too fast. The dealer said today that I'm running out of gear, ok, possible. But it still shouldn't be setup to over rev that easily and that much. Then goes on to tell me not to got WOT unless i'm in 2-3ft of snow. This doesn't make sense. Weights would probably help or gearing, I'm just worried of voiding the warranty.

8600-8800 seems much too high, but I'm no expert. Hopefully one of the knowledgeable guys jumps in on this.

 

[TurboJamie]

Do you know why that belt drops the RPM? I'm ok with that speed if that's what it's meant for but it shouldn't hit the rev limit every time i have it WOT. does hers hit the rev limit at 95mph?

If your hitting the rev limiter it maybe cutting the power. I am not sure as her's doesn't really hit the limiter on the lake in 4-6" of snow and to best honest I've never held it WOT on the trail. My guess is that you are experiencing RPM cut due to hitting the rev limiter.

Going to say an XS811 belt or Gboost belt will lower your RPM by about 300 or so. You can try those belts but if your running it out of gear no clutching or belt changes will stop that from happening. I have found in the past most flat land deeper snow machines could use more gear in them.

 

[Ottawaair]

Better check out clutching and make sure it's right. Sounds like maybe they put some 800 weights In there.
Check weights, springs, helix, belt, and gears if everything else checks out.

 

[Lid1]

I’m betting your running out of gear. That’s the cutting out. If your crusing at 10mph and go wot. What’s the rpm a 100 ft later ? If it’s more than 8150 or so. You need to add weight. You could also gear it higher but if you are an off trail guy you may hurt your off trail performance doin that. What elevation are you at what elevation do you ride at ? If may have high elevation set up in it. Light weights.

 

[Just-Pinch-It]

It’s a 2” track, 90’s is all your going to get with the gear ratio in it. When it over revs enough it will hit the rev limiter and stutter the ignition to lower the rpm. I would find a spot with 1’ plus snow and put it to the bar and see what the rpm’s is. I’m thinking if your on a surface with little snow those 2” paddles aren’t grabbing and your spinning the track, no load on engine, and the engine just over revs up until it hits the rev limiter. No different then having the sled on a jack stand and pinning it.

 

[Minus40]

I would say your running out of gear. Once the clutches shift out the rpm will rise. My Assault will over rev every time I try a top end run

 

[Al - 850 Matryx]

I appreciate all of the comments! I also now believe i'm running out of gear. I was able to find 1-2' of snow this passed weekend and notice the RPM's acting properly. At WOT i would hit 8200, when i went back on the hard pack trail i would get up to 160km's / 100mph and over rev if i held it there for any duration. I'm guessing this seld has enough power to gear up though like it was said above it will likely hinder my off trail performance. We haven't had the best winter this year so i never got to go play in 3-4' of snow. I'm thinking of leaving it alone until i truly get to test it in deep snow and then make a decision on gearing it up or not. Also, i did check and the parts all match up as per specs. Thanks again for all the replies!

 

[sixpack]

It’s a 2” track, 90’s is all your going to get with the gear ratio in it. When it over revs enough it will hit the rev limiter and stutter the ignition to lower the rpm. I would find a spot with 1’ plus snow and put it to the bar and see what the rpm’s is. I’m thinking if your on a surface with little snow those 2” paddles aren’t grabbing and your spinning the track, no load on engine, and the engine just over revs up until it hits the rev limiter. No different then having the sled on a jack stand and pinning it.

I think you hit the nail on the head...

 

[Tdykhoff]

Hi Guys/ Gals,

I'm new here, sno-checked a 2021 Assault 850 with a 2" track. I now have 25hrs. and about 600 miles. The sled is overrevving at WOT. I can't get more than 95-98 mph. I'm not trying to lake run but it seems slow! The engine cuts out once i over rev, then allows to pull again once the rpms drop below 7000. I've brought it to the dealer twice now (picking it up in 2 hrs for the second time) dealer says the track is rated for no more than 80-90 mphs??? It still doesn't explain the over revs at WOT. Wondering if anyone else is having similar issues? Whats your top end and what are you reving at?

Thanks,

I have the 650 version of your sled, 2" track. Rev limiter stalls me at 75 MPH, WOT, appears to trip at 7,800 RPM. Clutch weights too light?