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Not a banshee but need help!


coryv4

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i should have adressed this problem in jauary but never did and winter is coming and i need this solved. My sled ran good all season then one day it slowey started burning more fuel and the plugs started getting darker and darker. i switched plugs about 4 times in one day. by the end of the day i went from 10-12 mpg to 4-6mpg. my fuel pressure stayed the same so i know my pump isnt messing up. the carbs are spotless. the intake is a chamber airbox so no filters. the compression is the same as when i baught it, and reeds are tight.

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Sled? I have Polaris RMK 900 big sled! hmmm are you losing power by a notch? other than that to what im reading... The only thing I know that fouls plugs... wrong jettings ( it can even ride nice but motor not combinating right with air/fuel and its harder to tell with snowmobiles) Polaris has self-adjustment carbs, those are hand free elevation adjustment.. Thats why those snowmobiles are expensive.. I dont know what type of motor you got... Once i know i'll pm you with all the details to do... I work on snowmobiles all times.. My grandpa got 7 of them up the lake.. holler back buddy

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3 things come to mind......

 

 

#1 - Fuel pump diaphragm might be cracked and making pressure at low idle but develop issues at higher RPM.

 

#2 - Rings are going out on it. (Do a compression check and or make sure the motor was getting oil on that trip.)

 

#3 - You lost your crank seal.

 

 

:shrugani:

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fuel pressure is 3-4lbs at idle and 10-12 at wot

i dont think cranseal because there is no oil that goes inside the engine

comp is 130 stock is around 130

 

10milbanshee

its a sx 600 twin i never touched the jetting its 100% stock inside the motor it ran perfect for 2 seasons plugs were gold the whole time

same elevation

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