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Jeff Policky
Jeff Policky, Motorcycle Mechanic
Category: Motorcycle
Satisfied Customers: 2425
Experience:  Yamaha Gold, Suzuki Gold, Honda Bronze, Polaris Bronze, BRP
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My 1999 polaris big boss 500 6x6 atv is blowing smoke. No

Customer Question

My 1999 polaris big boss 500 6x6 atv is blowing white smoke. No its not coolant. Coolant levels haven't changed. Spark plug is very black, gas keeps getting in oil thinking it out. I have adjusted valves, checked timing, checked cam, new main jet 140 new valve needle n seat. The machine is very boggy it's like it's constantly flooding out. The fuel screw is 2 1/4 turns out on the bottom of the carb. Pilot jet is good and everything else in carb looks good. Just changed oil again after new valve needle n seat. Float seems good. Oil is thin again n smells like gas!! Compression is good. I'm at a loss here. Las time I pulled carb there was a little gas puddles up on the intake side of the boot. Now what to try? Need fixed ASAP for hunting Friday
Submitted: 9 months ago.
Category: Motorcycle
Expert:  Christopher replied 9 months ago.

Hello how are you today? I do not have a whole lot of experience with this particular model I can offer you at least one suggestion. If memory serves me the fuel tank is lower then the carb, this means the atv has a fuel pump. Check the vacuum line from the intake to the pump, when the diaphragm in the pump goes bad it will allow excess fuel to enter the intake. Pull that line while the engine is running, it should be completely dry.

Customer: replied 9 months ago.
Yeah checked that already. Thanks though
Expert:  Christopher replied 9 months ago.

Pinch the fuel line while its running and see if it clears out. do you have any blow back into the intake?

Customer: replied 9 months ago.
clears out. Yes gas blowing back into intake
Expert:  Christopher replied 9 months ago.

If the intake valve clearance is not tight, next step would be a leak down test. Here is a link for more info about the test. It will tell us if compression is leaking back into the intake.

http://www.dansmc.com/leakdown.htm

Customer: replied 9 months ago.
Did leak down test at 15% which is still ok
Expert:  Christopher replied 9 months ago.

Where is it leaking from?

Expert:  Christopher replied 9 months ago.

Is the intake boot rubber? I can not tell from the parts diagram.

Customer: replied 9 months ago.
No its metal
Customer: replied 9 months ago.
It's not an air issue it's flooding out