I noticed my 50 leaking oil the other day, Its coming from somewhere around the countershaft where the front sprocket is. One of my friends was leaking in the same place. Anyone ever had this happen? And the bike does'nt have many hours on it either its an 03'. So what is envolved in changing the counter shaft seal, do I have to split the case? If I do Im going let it leak. Any insight on this would be helpful.

 

Do you have a big bore kit? Cus if you do, then it's from the extra build up of compression inside causing the seal to blow out. Anyways, it's easy to change out the seal, and you don't need to split the cases.

 

Its all stock.

 

i cant think of any other way it could've blown out beside too much pressure in the engine. does air blow out when unscrew the oil cap?

 

check and make sure you crankcase vent isnt pinched off first
secondly clean off the area and check for tears in the seal
(usually the chain has come off and torn it some where)
next see if it is leaking where the shaft spins in it may have a bur on it or something affecting the leak
do some detective work
to swap it you just use a pick tool and pull out the old one then get a socket that size and tap it back in being sure to get it in straight,if not it will leak again

 

i forgot about the crankcase breather. good call z50. i can see why the seal go bad cus i always get sticks and leaves and stuff stuck in the case cover.