My sportsman 500 over heats constantly. bubbles constantly come out of the rad and it creates pressure and blows all the antifreeze out the vent hose. could this be a head gasket? no water in my oil, no white smoke. and it runs great.

 

if theres air inthe antifreeze when its running and the bike isnt boiling over form overheating then i would say yes theres a head/head gasket gone.

 

Whats happening first? The bubleing or the overheating? If there are no bubbles and it is running cool then it's normal. The bubbles are coming from the antifreeze evaporateing. Yes even anti-freeze evaporates. If it overheates first check your normal colprites mud in the rad (front and back) or the rad fan actually coming on.

 

It comes out your rad cap AND your overflow? Hmmmmm. Posibly a head gasket, but it really shouldn't be coming out of your rad cap, just the overflow. I can't speak to ATV's but on my log trucks if we suspect a head we start it up cold with thte rad cap off. If you see bubbles it is likely a head/gasket problem. IMO.

 

there is constantly a trail of bubbles comming out of the rad. when you take the cap off you can watch them. does it when its cold. i was just making sure everyone thought it was a head gasket before i go and tear apart the whole machine. is it best to take the motor out to change the head gasket?

 

If you goto any garage they should have a head gasket tester. It is a special tool that fits on the rad cap hole and sucks the air in the rad through a special chemical that changes colour if exhaust gas runs through it. We have it at our garage, we are a chrysler dealer but other garages should have it.

 

Do you do any mud running? - your radiator could be clogged.
Is the anti-freeze mixed properly for your ATV.
Is your thermostat defective?

 

if he is seeing bubbles in the rad. he has head gasket/head problems i would guess. if you have a leak down test down and its leaking air in the radiator then it will show air bubbles come out. just a thought.