is it normal that 850 163 cannot pull 72 weights?

[glowa]

My sled is 2019 axys 850 163 with replaced engine after crank bearing failure, now around 40 hours. The altitue I ride in mostly is around 1000-1300m (3200ft - 4300ft), my sled goes to around 8000rpm with 72 weights. I would normally think that my sled is simply broken, or some issues with clutch, or maybe engine was improperly positioned during replacement, or maybe the fuel here is bad (I am outside of US), but at least 2 of my riding buddies have similar problem (both on 2020/21 KHAOS). According to manual the weights are correct for this altitutde, the primary spring is also correct according to manual, I believe I also read on this forum here that people reach like 8400 with these weights. What could be the problem for us?

Oh btw it is funny but one guy went down to 66g weights to get around 8400 RPM!!! on 850! I believe on my 2014 RMK I used 66 or 68g weights

 

[Wheel House Motorsports]

I know the OEM weight chart often results in sleds only running 8-8100 rpm often. so it would not be suprising if your slightly over weighted. If you drop a large amount of weight with very little change to RPM or way different the recommend chart then its most likely a primary with worn components. From hard riding its not uncommon to have clutch issues in as little as 500 miles if extreme belt heat was present.

Check all primary rollers and the bushings besides the rollers. Those often wear out and fail and its common to lose around 150 RPM for each washer that has melted and is gone.

We run 66's to get 8400 rpm at 6-8k feet no problem.

 

[akmclean]

This may be obvious to you but check belt deflection and throw a new belt on if yours has more than 7-800 miles. Most common rpm loss casues I've come across.

That being said I also cant seem to pull 72s even at 1500' elevation with a 2021 850 155. I put SLP magnum force weights in and dropped to 71.6gs and get 8100. I will pull some more weight next ride and see where I end up, but I've had previous 800s pull 70gs no problem.

 

[glowa]

I am sorry but I just read my post again and I accidentally skipped some important details

I have modified primary and secondary clutch by Patrick Custom Carbon + lightweight brake disc. This entire setup has around 500km. The helix is 42, drive spring is OEM black 120/320, sorry I do not remember the driven clutch spring but it is OEM spring

I also have ceramic coated black SLP can.

The belt was definitely worn out as it has blown on a ride recently, I replaced with brand new and after 1 day riding I do not see increase in rpm.

Clutches are clean (I clean them often)

I am unable to say if this issue was last year when I installed Patrick carbon clutch, I rode very little last year and simply did not look at rpms but I have a friend with 2020 Khaos 163 who has it all stock and since new (now like 50 hours) could never reach the rpm with 72 weights


And now in regards to @akmclean answer!! I checked everything to resolve this issue but in fact I did not check belt deflection, however I am used to the fact that loose belt is squeaking (my belt was not squeaking) and the sled is kind of lazy off the start (I do not believe it was lazy)

I would be looking more towards some settigns on Patrick Carbon clutch (black spring correct? probably yes, helix?). Thoughts?

I read so many times on this forum people writing about their sleds doing 8400 rpms on 72g weight, are they lying? Am I just unlucky? What about my buddies? I do not know a single person (not many of us here) that can run 72gs

 

[G-Force]

it's a TIGHT belt will squeak. a loose belt will be quiet. Double check your deflection / measure it per the manual. Should be easily pulling 8300-8400 with a 72g and the rest of everything else stock at those low elevations.

 

[glowa]

hm I always thought that loose belt is squeaking? Am I mistaken?

 

[summ8rmk]

hm I always thought that loose belt is squeaking? Am I mistaken?

Excessively tight belts will make noise at idle, pre-engagement.

The noise comes from the center shaft of the primary 'burning' the belt.


Sent from my SM-G998U using Tapatalk

 

[glowa]

I thought the tight belt is moving the sled forward without throttle?

Under what circumstances the belt could become too tight? If it is initially set up correctly it could only become looser when worn out, am I right?

 

[summ8rmk]

I thought the tight belt is moving the sled forward without throttle?

Under what circumstances the belt could become too tight? If it is initially set up correctly it could only become looser when worn out, am I right?

U r correct.
Too tight and the sled could move at idle. Too tight could come from the deflection screw backing out.
If ur belt is making noise under load, u may have a broken sring or getting water on the clutches.

Sent from my SM-G998U using Tapatalk

 

[chevy_man]

I am sorry but I just read my post again and I accidentally skipped some important details

I have modified primary and secondary clutch by Patrick Custom Carbon + lightweight brake disc. This entire setup has around 500km. The helix is 42, drive spring is OEM black 120/320, sorry I do not remember the driven clutch spring but it is OEM spring

I also have ceramic coated black SLP can.

The belt was definitely worn out as it has blown on a ride recently, I replaced with brand new and after 1 day riding I do not see increase in rpm.

Clutches are clean (I clean them often)

I am unable to say if this issue was last year when I installed Patrick carbon clutch, I rode very little last year and simply did not look at rpms but I have a friend with 2020 Khaos 163 who has it all stock and since new (now like 50 hours) could never reach the rpm with 72 weights


And now in regards to @akmclean answer!! I checked everything to resolve this issue but in fact I did not check belt deflection, however I am used to the fact that loose belt is squeaking (my belt was not squeaking) and the sled is kind of lazy off the start (I do not believe it was lazy)

I would be looking more towards some settigns on Patrick Carbon clutch (black spring correct? probably yes, helix?). Thoughts?

I read so many times on this forum people writing about their sleds doing 8400 rpms on 72g weight, are they lying? Am I just unlucky? What about my buddies? I do not know a single person (not many of us here) that can run 72gs

You're running all sorts of aftermarket parts. Anything you change in the clutch will have an effect on it.

Don't worry about what other people do. Let the sled tell you what it wants. Try a 70, 68, 66, etc until you find what works.

Mine has an SLP helix and spring, requires lighter weights than stock chart but it will pull harder up a hill than my buddies sled with stock clutching. He's running heavier weights but mine pulls harder, both running 82-8300.