i have a 92 yz 250, when i run it i smell antifreeze, not bad but every once in awhile. the fluid level hasnt dropped,but i was riding i time and got white smoke outthe exhaust, shut it off for awhile fired it up and ok. i just pulled the head off and the gasket/o-ring look ok, do you think it could be the bottom gasket? any ideas?
Drain the gear oil and see if it is "milky". This will tell you if the case gaskets are intact or not. Make sure it is not something simple like a cap gasket or a pin hole in one of the hoses. Also check the area where the hose clamps cinch down on to the hose...It could be dry rotted or worn.
When you do smell it....keep the bike running and get off and see if you see steam coming from somewhere.
I have a 92 YZ 250 also. How do you like it??