RPM Issues with 2012 Pro - Help Please

[JCasino]

Was out for my first sled ride yesterday up Meadow Mountain where the majority of the riding is between 7000-7700' and could not get my sled to pull over 7800-7900 on any pull. There was about 2' of powder and about -5 air temp so pretty light stuff. Sled ran awsome in the mid-range, never a bog, and throttle response was bang on. WOT however would stop at 7800 with the odd blip to 7900. No codes have been flashed either.

Last season, my sled was completely stock and would pull 8150-8300 on any pull, though most local areas are closer to 6000'. Over the summer, I swapped out the 155 for a 163 track, put on an HPS can, SLP blue-pink with metal glide washers, delron on secondary, fuel filter, drained and filled with fresh fuel (91 Shell only), new plugs, and cleaned exhaust valves. I was thinking that my RPM's would have increased with the new spring and the can but I'm going the other way. Weights are the stock 10-62's as well.

So, where should a start? I can take it to the dealer but then it's going to be 2-3 weeks as they are really backed up this time of year. I just want to go through everything I can before taking it in. Could this be a TPS or other electrical/computer type thing? Almost seems like some type of limiter is kicking in at 7800.

 

[cs5]

Start with the basics, I would throw in another set or my old set of plugs just to see, I have had bad plugs out of the box before. Next I would look at what you changed, the can for example I would throw the stock one back on just to see if it makes a diff, cans do not gain HP and some lose HP worth a try. Then I would look at my springs, I think the SLP ones are very good but when my stock spring broke on my 11 PRO it did exactly this. The way it bound up the sled worked perfect but would not pull past 7800 RPM. Worth having a look if you haven't already. Also on my 08 when I added the Delron in the secondary I lost RPM and never could understand why. Last thing I would look at is the belt, did you change it or is it the same? I have had a new belt that was a little longer than my old one just slightly and it screwed my clutching up completely as well.

 

[poo88]

The stock spring is a 140/330 I believe an the slp blue pink is 140/340. So I would think maybe throwing a lil less weight at it would clear that up. Someone correct me if I'm wrong but that makes sense in my head lol

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[Chrisco]

The stock spring is a 140/330 I believe an the slp blue pink is 140/340. So I would think maybe throwing a lil less weight at it would clear that up. Someone correct me if I'm wrong but that makes sense in my head lol

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No the new spring should make it pull more rpm. How much powder were you in ??? were your intake vents plugged starving the engine ???

 

[poo88]

No the new spring should make it pull more rpm. How muck powder were you in ??? were your intake vents plugged starving the engine ???

I clearly don't understand clutching lol.. thanx fer the correction

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[JCasino]

Chrisco - I agree. I was expecting to see higher than normal RPM's with the can and the new clutch spring. There was about 2' of powder and I was clearing snow from the intakes all day, but even with them cleared, still only 7800. Idle and mid-range were within range however. Any chance this could have something to do with the longer track?

 

[gedakbx]

Chrisco - I agree. I was expecting to see higher than normal RPM's with the can and the new clutch spring. There was about 2' of powder and I was clearing snow from the intakes all day, but even with them cleared, still only 7800. Idle and mid-range were within range however. Any chance this could have something to do with the longer track?

163 polaris track or something else also are the 155s geared the same as the 163 pros?

 

[JCasino]

163 polaris track or something else also are the 155s geared the same as the 163 pros?

According to the maintenance manual, both are geared and clutched the same.

 

[ICEMAN#33]

hey can you tell me how many miles on your engine?

 

[markoo]

New track is making the motor work harder. Drop a bit of weight in the primary.

 

[DYSLEXIC]

did you take notice of the temperature? check coolant? just throwing that out there......it happened to me once.

 

[JCasino]

did you take notice of the temperature? check coolant? just throwing that out there......it happened to me once.

Air temp was around -5. Coolant was fine. Thanks though.

 

[JCasino]

hey can you tell me how many miles on your engine?

1250 miles at the start of yesterday's ride then put on another 50ish.

 

[JCasino]

I decided to start by taking the primary back to stock while getting ready for the weekend and noticed that the brand new SLP spring had some paint wear on the inside after 50 miles. Also, the jam nut showed some signs of contact with the spring. I looked at my original stock primary with 1200+miles on it and it showed no signs of wear and never made contact with the jam nut. I've also never had a broken primary on this sled. I've removed the SLP and metal glide washers and put the old primary back in as a starting point. If no change, then I'll do can and plugs as other have suggested. Fingers crossed that this takes care of it.

Is there any other underlying issue I should be looking for that could have caused the spring/jam nut to bind up? Seems that most people have no issues with the blue/pink so I still think its coming from elsewhere.

 

[BigB88]

I have been having the same issue with my stock 2011 pro 163.

 

[JCasino]

I have been having the same issue with my stock 2011 pro 163.

Gained back about 100rpm yesterday with the old stock spring and new spark plugs but still not getting 8250. Even with the 100 rpm less, it still felt better with the slp blue/pink so its going back on. I wanted to get this sorted out before putting my 13.1 PA head on but I think I might just go ahead and install it and then play with my weights.

Does the weight of the rider impact RPM's and the clutch weight that I'd use?

 

[Jeffpro800]

Could be coil bind in your primary, I've seen this before. Look at the spring seat, is it digging into clutch? Not a bad idea to slightly radius the sharp edges on your spring ends. How are your weight bushings?

 

[duck]

Gained back about 100rpm yesterday with the old stock spring and new spark plugs but still not getting 8250. Even with the 100 rpm less, it still felt better with the slp blue/pink so its going back on. I wanted to get this sorted out before putting my 13.1 PA head on but I think I might just go ahead and install it and then play with my weights.

Does the weight of the rider impact RPM's and the clutch weight that I'd use?

Of course the weight of the rider will have an effect. The sled will work easier with a 100 lb kid on the sled versus a 300 lb linebacker. the secondary will sense the load at the track much the same as riding the sled in heavy wet snow.....lighten weights as required to get the rpm back. Don't overthink the problem. Weights govern the rpm the engine runs at while the finish rate of the primary spring determines how much push will be created in the primary and height the belt will run at for a given horsepower in the engine. Mind you the spring rate has some effect on the rpm in conjunction with the weights. Keeping in mind that your particular engine will produce a certain amount of power (all engines not equal). This is why you need to tailor your ride to your weight, riding style, elevation and conditions. Were also talking primary clutch here, throw the secondary equation in the mix and its another story. Both need to work together. Olaev Aaen wrote a book on clutching and while outdated, does shed some light on the subject......

 

[M1K]

I also went to a 163 from a 155, and the only thing I changed was I dropped one tooth on the top sprocket and it usually pulls 8050 -8100. That was untill I contaminated my belt when the sled spent some time on its lid and injector oil had leaked onto my belt. Kinda of a bad place for the oil jug (imo)for those of us that have a hard time keeping the rubber side down.

 

[2010rmk800144]

i pulled my cluthc on my 2012 switchback assualt on the weekend and switched springs putting in a package im running now and i had a slp blue pink in there and i had wear marks on the inside as well

I decided to start by taking the primary back to stock while getting ready for the weekend and noticed that the brand new SLP spring had some paint wear on the inside after 50 miles. Also, the jam nut showed some signs of contact with the spring. I looked at my original stock primary with 1200+miles on it and it showed no signs of wear and never made contact with the jam nut. I've also never had a broken primary on this sled. I've removed the SLP and metal glide washers and put the old primary back in as a starting point. If no change, then I'll do can and plugs as other have suggested. Fingers crossed that this takes care of it.

Is there any other underlying issue I should be looking for that could have caused the spring/jam nut to bind up? Seems that most people have no issues with the blue/pink so I still think its coming from elsewhere.


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