Last three to four rides, my 858 will top out at 7600-7700 rpm MAX. The 5 rides on this machine prior, I had no issues hitting 8100-8200 rpm. I don't think it's the power valves , I adjusted bracket early on. I need and miss those 4-500 revs. The sled dealer in Kremmling had the Polaris boots in stock so I'll try to change them before my next ride on this trip. Sled has 300 miles
Clutch spring or spark plug boot?
- Thread starter koolaid
- Start date
Mine acted the same way, changes boots helped slightly, cleaned clutches and belt- also helped slightly but then super erratic and then popped a rod thru the block. I was thinking it was clutching but now not 100% sure. 10500+ feet
Stiffer springs fixed mine up here. Also check the rollers in the secondary. My stock ones were binding against the steel when you put pressure on them by hand. I swapped in an old roller cup I had lying around from an Acsender that rolled freeley. Not sure if thats causing this issue and not allowing it to backshift, but something to think about.
Both of mine are super sensitive to altitude. 9000 ft. acts good, backshifts, pulls, then gain another 1000 ft in altitude and it loses rpm and throttle response. Drop back down and it seems to gain it back. Most inconsistent clutching on any sled I have ever owned. I'm wondering maybe if the pipe could use a restrictor like some of the older sleds like the M7 liked. Maybe the pipe is just too loose at altitude, and it doesn't make the power. Kinda what it feels like to me.
Probably a combination of little things.
I have two flatland sleds that are run side by side. Same conditions, same miles (3,000 range on each), and we swap riders to verify.
The good one has run pretty consistently through the season. It is stock except for the updated flatland 120/265 primary spring. I did replace the worn out stock weights with another set of the same. Dumb thing is still on the original belt, spark plug caps, and everything else too.
I've been fighting a similar rpm issue with one. I call it the bad one.
The bad one is up and down with rpms. It's rarely down to the 7600 range, but enough to drive me nuts. The sled is finicky. It runs great and then it doesn't.
It is on the third set of SP caps. The updated version also started to break up inside the boot. This one also took out coils and stator.
Exhaust valves adjusted a couple times and cable eventually replaced. The cable had signs of rubbing by the servo.
Each change/repair seemed to bring it back to consistency for a bit. The good one still ran slightly stronger with side by side testing.
I started to try quite a number of clutching combinations with the bad one. I found that it is extremely finicky. This new primary is a gripper. This sled is right on the edge of too much or too little clutching. Cold belt/cold air is a completely different animal compared to higher temps and harder belt grip. The sled really needs two different clutch setups to run both. High grip drops rpms way down until the belt gets super soft on long runs. On those long runs, the rpms start breaking loose.
High rpm running gets into range where the weights are vertical and lose their ability to squeeze. Mid range rpms with this primary are in super grip range. New belts with less good belt/sheave contact let the clutch go through the middle rpms. New belts act like the rpm problem is fixed. After awhile, good belt contact holds down rpms if you can't get track speed and overcome the mid shift. Any little hiccup or slight loss of power from the motor exacerbates the problem. In my case, the bad sled has had a lot of hiccups.
The strange irony to all this is the good sled. The clutch sheaves have never been cleaned. The belt on that thing should be tossed in most cases. It's lost the ability to get a good grip and relies on the ol sheave squeezaroo. The dang thing pulls right through the high grip mid range rpms. Clamp the throttle for some goodies and drop back down to 7000 rpms, it climbs right back out again. That setup works pretty good unless you run top end rpms for long runs. The primary can't squeeze enough up there and it builds heat.
I have two flatland sleds that are run side by side. Same conditions, same miles (3,000 range on each), and we swap riders to verify.
The good one has run pretty consistently through the season. It is stock except for the updated flatland 120/265 primary spring. I did replace the worn out stock weights with another set of the same. Dumb thing is still on the original belt, spark plug caps, and everything else too.
I've been fighting a similar rpm issue with one. I call it the bad one.
The bad one is up and down with rpms. It's rarely down to the 7600 range, but enough to drive me nuts. The sled is finicky. It runs great and then it doesn't.
It is on the third set of SP caps. The updated version also started to break up inside the boot. This one also took out coils and stator.
Exhaust valves adjusted a couple times and cable eventually replaced. The cable had signs of rubbing by the servo.
Each change/repair seemed to bring it back to consistency for a bit. The good one still ran slightly stronger with side by side testing.
I started to try quite a number of clutching combinations with the bad one. I found that it is extremely finicky. This new primary is a gripper. This sled is right on the edge of too much or too little clutching. Cold belt/cold air is a completely different animal compared to higher temps and harder belt grip. The sled really needs two different clutch setups to run both. High grip drops rpms way down until the belt gets super soft on long runs. On those long runs, the rpms start breaking loose.
High rpm running gets into range where the weights are vertical and lose their ability to squeeze. Mid range rpms with this primary are in super grip range. New belts with less good belt/sheave contact let the clutch go through the middle rpms. New belts act like the rpm problem is fixed. After awhile, good belt contact holds down rpms if you can't get track speed and overcome the mid shift. Any little hiccup or slight loss of power from the motor exacerbates the problem. In my case, the bad sled has had a lot of hiccups.
The strange irony to all this is the good sled. The clutch sheaves have never been cleaned. The belt on that thing should be tossed in most cases. It's lost the ability to get a good grip and relies on the ol sheave squeezaroo. The dang thing pulls right through the high grip mid range rpms. Clamp the throttle for some goodies and drop back down to 7000 rpms, it climbs right back out again. That setup works pretty good unless you run top end rpms for long runs. The primary can't squeeze enough up there and it builds heat.
Sounds like you guys are chasing this RPM issue on your dime and time.
This sled has a few issues, my 21 Alpha had zero over three years.
2025 Catalyst 858 (300 miles)
1. RPM issue
2. ATAC /G8 issues. (bad handlebar switch?)
3. Emissions recall
4. Handwarmers don't work
5. Loud brake rotor noise
This sled has a few issues, my 21 Alpha had zero over three years.
2025 Catalyst 858 (300 miles)
1. RPM issue
2. ATAC /G8 issues. (bad handlebar switch?)
3. Emissions recall
4. Handwarmers don't work
5. Loud brake rotor noise
I agree that it’s a combination of things.
I also have been chasing the rpm issue in heavy load conditions. It’s my belief that it ultimately stems from lack of back shift in my case. I’ve done the new plug boots and didn’t really notice much of a difference. I do find however, that when the snow is deep enough to restrict some air flow and the clutch is hot and it’s possible I’m also pulling in hot air from somewhere under the hood it’s enough of a power loss that it’s just not gearing down enough to get those rpm’s back up. Is it “spring fatigue “ ? I don’t know. Maybe a stiffer spring in the clutch would help or even a better spring? I will be looking at trying to make sure everything is sealed up properly under the hood and possibly try the air box riser that is supposed to help with that.
All that being said I am still impressed with how much power it’s making at 7700-7900 rpm and the traction of that powerclaw track is second to none. I was in about 18” of fresh snow last ride and climbing through all lot of steep trees from 6500’-7500’. My buddies on their turbo doos were struggling to keep up in steep and tight technical trees . The agility of this sled is next level!
Dropped 300 rpm today changed my belt and it is back up to 8000. Belt had 600 miles on it. What kind of mileage are you guys seeing on belts before rpm fall off?
When losing rpms on longer pulls has always been the indicator I have used for belts wearing out. Changing it out gets it back up to the desired rpm on the pull and holds it. Not sure about the higher ripm with a worn belt...that one is new to me.
Well, less than 5 minutes into tearing into sled, I think I found the problem with my mine. The EGT sensor on the pipe has come loose and off. I did notice extremely low EGT numbers in the <100* range last ride and was scratching my head. I had mentioned earlier in season when installing Diamond S can that the sensor there was loose and removed with my fingers.
Attachments
For what it’s worth I tried a couple things today. The first was new rollers in the adapt secondary. Maybe a little better but still crappy. Went back to the trailer and installed my team secondary off my 2020. We were in 18 -24 inches of fresh snow but pretty heavy. Needless to say things were way better and seemed to get better as the day went on not progressively worse like with the adapt. Enough so that I think I finally know what I need to get it dialed in. This is just one day of testing but very promising. So promising I ordered a team boss secondary.
For the record both clutches had 45 degree helixes. 180-260 venom springs and venom rollers. Composite rollers in the team Turlon rollers in the adapt.
For the record both clutches had 45 degree helixes. 180-260 venom springs and venom rollers. Composite rollers in the team Turlon rollers in the adapt.
Exhaust Temp, not o2.
Per the parts diagram there are (2) 0630-330 Sensor, Exhaust Temperature. One is in the expansion chamber and one is in the resonator, as described on the parts diagrams.
