I bought an '03 400 Outlander yesterday from my buddy. He put on 500 miles since new. Very nice shape but was ridden once in 2 years. He said he had it covered in the backyard. I'm wondering if the old fuel is causing problems, (didn't use stabilizer on 1/2 tank of gas) not a smooth idle, seems to be missing, so I turned up the idle speed. Still bit of a lumpy idle Also exhaust is noticeably black. He said he put in synthetic oil a couple of years ago. The oil level is normal but I can't say for sure if it's burning the oil without riding it for a bit. Can the piston rings be shot already?

 

I would first problably change all of the fluids if it has been sitting for a long time and if its smoking that could be cause by the airfilter. But check up the regular maintanance stuff like the spark plugs, oil and if its been ridden for a while it may need to be serviced so you can get the valves adjusted