xr600r smoke when the throttle is off

[xr600r]

hi ,i noticed a bit of smoke coming outta me xr a little while ago so i did some tests and came to the conclution that my valve stem seals must be leaking as is gave a puff of smoke after i shut the throttle down a hill and then turned on the gas.so i replaced all my valve stem seals all went well was well happy.well now its loads worse!and i mean i cant drive it on the road cos i fill the street with smoke.can anyone relate to this?ive since had the head off again and checked everything and all seems ok.the onlything im not too happy with is the head gasket.i bought some off good old ebay nice and cheep.its alittle different cos its not metal (only round the barrel) would anything else cause this amont of smoke when i let the throttle off down a hill?any help would be g8.

[themoudie]

Aye XR600R,

Genuine head gasket required!!!! Some of the 'pattern' ones are as robust and accurate as "Throwing a pork sausage up a close on a dark night, wi your eyes shut!"

Worn valve guides/valve stems or piston rings and bore come to mind. Obstructed engine breather as well?

I am sure others will chip in their pennies worth soon. Sorry to not be more positive, but gasket/sealing problems often appear on singles because of the large volumes involved in each suck, squeeze, bang and blow cycle.

Hope you resolve the problem soon.

Bill

[bikeseamus]

Check for cracked rings...who installed the valve guide seals?  Any scars on the intake valve stems?  A crack in the head, if it involves the oil gallery, will display those symptoms as well.
   ..... also...are you overfilling it with oil..?. and...is your oil 20-50 of the correct 4 stroke variety... I have seen people put in 2 stroke motorcycle oil...and that happens.  Crankcase ventilation is important, but if your vent feeds into the airbox, I'll bet your air filter compartment is PLENTY oily if the rings are cracked, and that will smokemup baby, and I don't mean maybe.

    Check all those things and you will find at least one culprit causing it.  It's not the Starship Enterprise.  Keep us posted.