I recently purchased a used 2000 Prairie 400 2wd. It starts up first attempt and runs smoothly but Idles a bit high. The problem is Gas is getting into the oil, It does not smoke a lick nor blow anything out the exhaust. I changed the oil in it the day after I got it 2 weeks ago and checked the oil and it was high on the stick, dark and smelt strongly of gas.

It sat for nearly a year before we bought it and would not run at all with out the choke full open untill we sprayed some carb cleaner in the carb, Now it will run with out the choke but Idles high. Anyone got any insight on where I should look first? Or am I looking straight at bad piston rings?

 

The term "choke" is really misleading on that quad (and others). It's not really a choke that you would imagine but it is rather a fuel enrichner system with a plunger or valve that opens and closes. Sometimes old fuel will leave gummy residue or even some corrosion would form and the plunger would hang open allowing excessive fuel into the carb. That explains why crankcase gets mixed with fuel and also explains why idle is high even w/o choke off - too much fuel. So, follow the choke cable to the carb and remove/clean the plunger and where it sits in (bore) with wire brush brush or fine woold cloth. If that checks out fine, check compression or do leakdown test to see if the engine is tight.

 

Ah, thank you for the insight! Hopefully tonight I have some time to tear into it and check the "choke" cable and change the oil again.

 

Forgot to mention...
If it's not found to be the "choke" plunger sticking, check the carb float valve. The valve's rubber tip might be worn out and/or the valve seat on the carb might have old fuel residue stuck to it, and fuel might be leaking and overflowing in the carb bowl and the excess might be flowing into the cylider.

 

Thanks Again!! Hope to get to tear into it this weekend.