Hi,

I have a 2004 Gas Gas 300 Pro that seemed to be burning transmission oil. It would smoke alot and I would always have to add oil. It is also very hard to start compared to several of my buddies similar bikes. We just got done tearing the motor apart and replacing all of the crankshaft seals. After putting it back together and running it, it is still doing the same thing.

It has always and still runs fine once its started. Just burns alot of oil. Any ideas?

Thanks,

TJ

Hi,

I have a 2004 Gas Gas 300 Pro that seemed to be burning transmission oil. It would smoke alot and I would always have to add oil. It is also very hard to start compared to several of my buddies similar bikes. We just got done tearing the motor apart and replacing all of the crankshaft seals. After putting it back together and running it, it is still doing the same thing.

It has always and still runs fine once its started. Just burns alot of oil. Any ideas?

Thanks,

TJ

did you change bearings as they run in the gearbox oil so if the inner seals gone on the bearing oil will get through.

did you replace centre gasket ?

Hi,

I have a 2004 Gas Gas 300 Pro that seemed to be burning transmission oil. It would smoke alot and I would always have to add oil. It is also very hard to start compared to several of my buddies similar bikes. We just got done tearing the motor apart and replacing all of the crankshaft seals. After putting it back together and running it, it is still doing the same thing.

It has always and still runs fine once its started. Just burns alot of oil. Any ideas?

Thanks,

TJ

All that work and still burning oil? - that sucks !

Sorry to say but sounds like (if I have understood you correctly) that the crank case is pulling in gearbox oil (?) did you check the condition of the mating faces of each half of the cases? Check for flatness/localised high spot/ localised low spots. Possible also that porosity or cracks / cracking are allowing gear oil through to where it dont wanna be.

Assume that the crank was in servicable condition at the point where the new seals sit /make their seal? And that the seals were not damaged when fitting (it does / can happen) Best of luck sorting this out though.

Edited December 16, 201015 yr by Scoobydo

All that work and still burning oil? - that sucks !

Sorry to say but sounds like (if I have understood you correctly) that the crank case is pulling in gearbox oil (?) did you check the condition of the mating faces of each half of the cases? Check for flatness/localised high spot/ localised low spots. Possible also that porosity or cracks / cracking are allowing gear oil through to where it dont wanna be.

Assume that the crank was in servicable condition at the point where the new seals sit /make their seal? And that the seals were not damaged when fitting (it does / can happen) Best of luck sorting this out though.

All of the metal parts (case halves, etc) seemed to be fine. It all looked like it was in very good condition. We did replace the center gasket as well. I had a friend help me who has alot of experience with small engines. I just hate the idea of having to pull it all out and apart again. Im very tempted to just ride it.

I did my mains last year on me 07 and i think they had some changes on the mains at some point prior to the 07 model the dealer informed if i recall correctly.So have you purchased the correct ones ? its the most likley source of failure is the mains seals. I also had a non factory GasGas gasket sent in the post and it fitted very badly, so i purchased another one directly from GasGas uk and the difference in fitment was amazing.

Well best of luck as its a bitch of a job.