2005 EC200 Continual RH Crank Seal Failure

[NHtrailrider]

I have a 2005 EC200 that has eaten two RH crank seals in less than 1 hour of run time. The bike is burning trans oil.

I replaced the inner o-ring on the crank both times. The first replacement I used the all-balls kit and the second I used an OEM seal. The seal spacer did have a small groove in it that I sanded down smooth.

The bike has a fresh replated top end and new piston. It starts easy and idles well. It smokes excessively when on the gas in the mid-top range of the throttle. Both PV and crankcase vent hoses are open and unclogged.

I am now thinking it could be the center case gasket? Would a leaking center case gasket allow trans oil into the combustion chamber? Am I missing something or does anyone have any ideas?

[SS109]

If it's destroying right hand crank seals then that would lead me to believe the crank bearing on that side is failing.

[Jacob 'Berg]

+1. If it is going through crank seals in an hour do not wait to split the cases and replace the bearings. ie. I would not continue to run the bike, or you will be replacing more than bearings.

Crank may need new conrod and big end bearing if it has not been done, given the bikes age. Cheap insurance while you have the cases apart.