RM 250 crank seal?

[acw592]

Hey Everyone, New to the forum. We have a couple of 4-stroke atv's, Honda 400EX& 450R and my son and I are getting into dirtbikes too. We bought a RM 250 which supposably has a new topend. The guy I bought it from said he thought it had a bad right side crank seal. When I brought it home, the rear wheel and swingarm were covered in oil. It smokes bad, and the oil really comes out of the pipe down below where it connects to the silencer. The gear oil was low when I brought it home..sounds like a right side crank seal. I was wondering if there is anyway to tell for sure. Im down to the crank seal and I cant see any tears or anything. It's in just slightly crooked, but not by much. I don't have a pressure tester or I would give that a try. Anyone who has done this, I would appreciate a little guidance. Thanks!

[JDR215]

hi there,
to be honest with u, i dont really think u will visually see any damage to the seal from an external veiw. seals wear out over time, and will just leak even if they dont have any noticeable damage. all the symptoms sound like its the seal that is causing trouble.
Bite the bullet and change both side seals.

[spartanbiker_117]

Instead of gear oil, you can put in ATF and it will smoke white.

[RMudslinger 250]

First off i would replace the seals in the engine,cheap insureance,also you said swingarm and rear wheel were oily,is it oil from pipe or do you have a leaking kickstart or output seal?

[RMudslinger 250]

Hey also heck of a right up in 2-stroke kb, on leak down tester digging up stuff to build me one.

[acw592]

I wish it was JUST crank seals. I checked the play on the crank shaft...up and down-side to side, it's got all kinds of play. Crank bearings are shot. Looks like I'll be tearing it all down. Was hoping to be riding soon.....

[JDR215]

unlucky, let us know how it goes when u fix it up.