Ok my buddy has a 98 grizzly 600 well now a 630. I know it has comprsion and brand new vavles. It runs great but just burns oil. I think it is from the vavle gides and so does his dad who is a airplane mechinic. it was just bored about 3 months ago with new wesico and rings and then a valve bent so they but new valves in it. Any ideas would be appreciate B/C i am tired of getting smoked out!!

 

Either valve guides ot the valve guide seals.

What caused the valve to be bent? And when did it start burning oil relative to the bent valve?

 

I am not sure what caused the bent vavle i think he sunk it but not sure. IT start bruning oil right before the bent vavle i think not sure thought but i am pretty sure that it is guides or seal. What else could it be! thank you for the fast reply!!

 

Well...does it burn oil after it's warmed up? Bad valve guide/seals will allow oil to run down into the combustion chamber over night and thus when started the next day, it will smoke until that oil is consumed. If it smokes after it's warmed up, could be the rings.

Run a compression check. Then squirt an oune of oil in the cylinder and run check again. If pressure comes up; worn rings. If it stays the same, bad valve guide, seals or valves not seating.

My girlfriends 04 Bruin started burning oil on start-up but quit when warmed. I switched to Amsoil 0w-40 synthetic atv oil and it cured that problem.

 

Just to clearify, any engine will show a higher compression when oil is added. If the compression test without added oil is within specs, then there is no need to add oil for a second test.

 

That's true and I am sorry I failed to note that.

 

That is a false statement..
Here is how you do a compression test right.
1st check your valve clearance and if they are out of spec adjust them.
2nd start your engine and let it warm up for a few minutes, then stop the engine and remove the plug and attach the tester.
3rd you crank the engine with the electric starter with the throttle wide open until the reading on your tester stabilizes.
If you test an above max pressure reading check the head,valves, and piston for carbon deposits.
If you test a reading below minimum pressure squirt a few drops of oil.
if you then test a higher reading after the oil you have a worn or damaged piston
if you test the same reading after adding oil you may have defective ring(s), valves, cylinder head gasket, or piston is possible(hole or crack in piston)
That is the proper method.
On my old Kodiak 400 the max pressure was 227 psi and the minimum was 177 psi
Standard pressure at sea level was 203 psi
A 600 grizz manual will tell you the pressure specs.