Yamaha QT 50 Carb Question UPDATED! By gbtr6 (Read 4,143 times)

[Moat]

May 1, 2013 11:02:35 GMT -6 gbtr6 said:

... and if the case is open to the bottom of the crank, isn't it possible it could scavenge some oil to the piston and out the exhaust side?

There is an oil seal between the gearcase and crankcase. If the seal is bad, then yes - it can leak gearcase oil into the crankcase, causing an excessive amount of smoke/unburned oil out the exhaust. Normally, the level of gear oil will remain constant, as there's not many places for it to go (unlike crankcase oil in a 4-stroke) - but if a crank seal is leaking, you may see the oil level drop over time, with no other visible leaks. Has this one's oil level been dropping lately? Given the scoot's age, a bad seal is definitely a possibility.

Also, the oil injection system in QT-50's have been known to allow oil to dribble into the motor when parked - not sure if it's a worn pump or bad check valve (if it even has one?) that causes that. Some folks just disconnect the pump and run pre-mix, with no problems.

[LUKE]

omg, moat is here!!....honestly, you kinda impress me with your knowledge in scooters, been following your posts.

[gbtr6]

Did a little adjusting on the cable for the oil injection pump and it doesn't spit nearly any oil. Could have been just not warmed up or the oil pump was sticking. When I started on it, the throttle cables and the oil cable probably too were sticking, wouldn't close. Think I have it solved. Now... anyone have a big bore kit they don't need!

Perry