what would cause drops of oil to come out of a 2007 250 sherco gearbox breather apart from too much oil in it. i noticed the fill plug isnt seating great. i plan on ordering one from splatshop tomorrow.

Leaky crankshsft seal. Pressurizes the gearbox. The Viton seals provided by Splatshop are recco. as they are better at resisting the alcohol induced fuels.

Both sides may be replaced without splitting cases

Edited September 12, 201213 yr by copemech

i changed the seals today but it's still the same. it only pumps it out when the engine is warm. any ideas?

My experience with these things suggests that even with all things perfect(from new) they may spat a bit if run hard. They find their level.

One wants to tip the bike at a 45 angle to get all the old oil out when draining or the addition of 450 ml of fresh oil may be too much and it will spat the excess.

There is a bit of test that one may do to hopefully insure the crank seal on the clutch side is sealing. The trans vent tube should allow normal atmospheric pressure to the gearbox, if you submerse the end of the hose in a cup of water and it is making bubbles, then something is pressurizing the gearbox side of things. Carefull with this, as a crank seal can just as easily suck water in as blow out, so clear hose is preferred.

If it is leaving puddles, something is odd.

Another thing I have allways done is route the vent tube up over the carb, then down to the skidplate. This means vent oil runs back in, And water (due to shock cooling) must run up before entering motor.

Cheers,

MC

cheers copemech. i'll try that

i checked it earlier and its definately drawing air in from somewhere. its fine until it gets warm then air bubbles start appearing in the cup. any ideas?

i checked it earlier and its definately drawing air in from somewhere. its fine until it gets warm then air bubbles start appearing in the cup. any ideas?

I think it would be logical to expect some normal expansion of the air in the gearbox as the motor warms, yet that should stabilize. A constant unexplained stream, or pressure against the tounge would suggest a problem I would think. Other than seals there have been no reported problems that I recall.