2013 pro not pulling rpm at elevation

[sketch96]

running at approx. 6000ft I cant get above 7950 to 8000rpm in a good deep snow pull. have dropped from 66grams to 64grams to 62grams and the rpm hasn't changed. Have tried 2 different clutch kits. using the blue/pink primary spring and black/white secondary spring. also have a c3 belt drive with 5.41 gearing. new motor with mtn tek fix kit and head . hps can, stock pipe.

I run shell 91 fuel and legend oil. I have noticed my plugs look carboned up and rich. been running the iridium plugs. Oil pump is turned up 2 turns and premix 6 oz oil per tank of fuel. vented stock oil tank cap.

anyone have any ideas. I thought changing weights would bring the rpms up!

 

[Lococoin]

I had the exact same issue and was running a new belt. Blew that belt recently and installed a new one and I'm back to 8300. I was about 7950 before. I had deflection set perfect on the other belt. Not sure why it never pulled rpm with that other belt but maybe try another one in yours just to see

 

[sketch96]

I had the exact same issue and was running a new belt. Blew that belt recently and installed a new one and I'm back to 8300. I was about 7950 before. I had deflection set perfect on the other belt. Not sure why it never pulled rpm with that other belt but maybe try another one in yours just to see

will give that a try, belt was new 3 rides ago. Fussy about deflection and clean clutches but will try anything now.

 

[powder junkie]

If both clutches are clean and no broken spring, Id check the VES too

 

[sleded1]

Also, recheck your compression,,

 

[Frankenytro]

I sure hope 5.41 it a typo... But I would be checking primary spring and compression first. let us know what you find!

 

[Highclimber]

When you did the mtntek drop in did you put the timing key in? Also exhaust valve springs? You didnt mention that. It comes with the kit.

 

[sketch96]

The sled came with the mtn tek kit installed. I havent checked the timing key yet but it is something i have been thinking about. I have cleaned the exhaust valves. Just checked compression and its even cyl to cyl at 125. When i got the sled i took the top end apart to check ring gap and it was too tight, renikasil the cyl and new rings.

Yes i made a typoin my first post. Gearing is at 2.51. Im 6'1 240 before getting dressed. The exhaust valve springs are new and are pink, pretty sure they come with the mtn tek drop in kit. The head is mtn tek 13.1. I have put 2 sets of spark plugs in in 4 rides and noticed i have black soot on the tipps when pulling the plug boots off to check plug readings. Im gonna replace both boots and put some dielectric grease in them.

gonna check the timing first, change the belt. Try it again. When i was down low coming back from the renshaw with 62 gram weights it would hit 8550 on the trail no load flat ground. Just wont pull rpm up high under load.

 

[Highclimber]

I did same as you on the oil thing when i did the mtntek drop in, found to be using to much oil with pumped turned up and vented cap. I am slowly turning pump back down and monitoring oil use closely.

 

[BILTIT]

I am in the same boat as highclimber, once i vented my tank my oil usage went way up. Slowly cutting it back so i don't leave brown streaks all the way up each hill i climb.

Not sure if it effected top rpm but i will find out next trip.

 

[Highclimber]

Fyi i didnt vent my cap, i went with the skidoo cap. Shhhhhh!!!

 

[BILTIT]

Lol i went with a tank vent, cap vents are still too small for my liking.

 

[sketch96]

I did the hot pin method under the stock cap. Worked very well. But yes the oil usage has gone up quite a but. I actually had it turned up 3 turns and premixed 1oz per gallon of gas before. This last ride i turned the pump back down 1 turn and only added 1/2 oz of oil per gallon of gas. Used a half litre of oil to about a half tank of gas. Didnt help the rpm issue up high tho, same as before.

is there a way to check the exhaust valve solenoid to make sure its working properly? The sled starts up on the second pull every time, idles good never bogs or hesitates. Just under load at elevation wont pull over 7950-8000. Seems like its a power issue. Timing off or maybe an injector dumping too much fuel dont know. smokes up my shop pretty quick when i run it at home!!!

 

[JMCX]

If your air/fuel is normal you can burn 20:1 oil mix and have clean plugs. Something is causing you to be fuel rich and that will hurt power. You may be on the right track with the exhaust valves but it could also be something like a failing pipe temperature sensor or too much fuel pressure. The plugs look the same?

 

[sketch96]

well found the issue. The timing key that comes with the mtn tek drop in kit was installed backwards by the previous owner.

Never assume anything!!! I bought the sled from an apprentice Polaris mechanic who works for the Polaris dealership in grande prarie!!!!!!! First thing I looked at after buying it was the ring gap after he told me he honed the cylinders to fit the rings!!!!! Unfortunately I had already bought the sled from him and just happened to ask him the question before leaving with the sled. When I looked at the ring gap it was too tight. Was a new motor replaced on warranty and he added the drop in kit. I ASSUMED buying a sled from a dealership mechanic it would be done right........boy was I wrong. I had to get the new cylinders re nikasiled and put a new set of rings in

pulled the mag to check the key......good thing as now I see the crank seal is leaking oil pretty good......as well as the key is in backwards!!! WTF! brand new bottom end with about 500 miles on it.

Don't ever assume the dealers have good mechanics!!!!

 

[BILTIT]

Imo, not many dealership mechanics are good mechanics (especially the young ones). I used to be a mechanic so I know full well.

Sent from my SGH-I337M using Tapatalk

 

[Highclimber]

I figured timing key was not put in, did not think about in backwards. Glad you found your problem though. Good luck going forward.

 

[AreWeThereYet]

I'll say it,.. Countryside Motorsports?

 

[sketch96]

im going to put a stock key in. That will advance the timing 3 degrees. from where it was at least. Talking to a reliable source they highly recommend not advancing the timing from stock for reliability.

 

[sketch96]

i'll say it,.. Countryside motorsports?

yes!!