my friends '05 450 r is puffin white smoke when he revs it... it smells like oil and not antifreeze which i thought would be the smell due to a blown head gasket but what else could it be with the white smoke... we are going to be ripping his bike apart today to check pistons and what not

 

Probably the rings. You have to remember these 450's have high compression and the short pancake pistons. This leads to alot of fuel blowing past your rings lowering the viscosity of your oil very rapidly. You have to change your oil at the proper manufactural intervals and based on how you run your machine. If you are beating on it all the time change it more than what it says in the book. You cant hurt it by changing the oil more often than it says

 

it still has a good compression though so im not sure if its the rings anything else it could be

 

did you use a compression guage to determin that or are you going off how it kicks. It doesnt take much to burn oil in a 450

 

yea the compression on it was just as good as the compression as my '07

 

White smoke means coolant, blueish white smoke means oil. Bad rings or valve seals lead to oil burning, head gasket leads to burning coolant, also could lead to oil and coolant mixing which would show milky oil. Are any of the fluid levels down, oil or coolant? That is also a way to see.

 

its not coolant oil was recently changed... its whitish smoke and smells of oil burning.. the thing that blows my mind is that the compression is still good... wouldn't seals broken or rings broken make the compression lower? o and it seems ot only really do it when it it first started

 

A way to tell if rings are bad is to do a WET compression test. Do a normal one first to get base number's, then pour some oil in the cylinder and redo the compression test. IF the numbers went up say 20-30% or more than the rings are bad.