Help!Please,I have a polaris 500 it was running great till something I hope not major happened.
I will fire and run at low(idle) speed.I have adjusted valves didn`t help! Seems like even at idle it is blowing exhaust back through the carb into the airbox! I know this because it used to suck my hand down in a 3/4 inch hole in the top of airbox!Now it`s blowing air through this same hole! Can anyone tell me what the deal is? Dead Polaris,needed for wife with disability.Help please!
Thanks David&Patricia

 

is the crank vent blocked. sometimes in the crank builds up pressure that blows back up. just an idear.

 

Thanks I`ll check! Is it one of the two small hoses that also attach to the airbox?
David&Patricia

 

yep. it goes form the air box to the crankcase. i would check all the hoses and vent line to be sure there clear and free being pinched.

 

It is very likely that the exhaust lobe on the cam is worn, it's a known issue and will cause the problem you describe.....

 

Thanks cam lobe problem,yes my polaris dealer said something like that is common with this year.Is their a cure?
Thanks David&Pat

 

my 96 sportsman had the same issue. Ran like it would in reverse with out ovderride button pushed. It was my cam. Exaust lob was worn.

 

talking about vent lines, I checked mine before I head out on a trip and I found spider eggs in my vent tube under the seat for my carb, imagine that lol

 

you never know where the pestky critters block passages.

 

You'll need to replace the cam and followers, the new cam should have an added oil port. Change the oil and filter every 500 miles or so....