i took the transmission off and inside the housing there was lots of crap built up on the inside. black grease looking stuff. i noticed that the rubber boot that covers the part of the clutch fork is torn. so could that let stuff in to the housing or maybe the seal is leaking? how would i clean the tranny off (inside and out)?

Brake cleaner works good.

it is cluch disk material, normaly. break cleaner and a rag will clean it up. if you are doing a clutch I recomend a new crankshaft end seal.

~John

as stated above, brake cleaner+ rag.
A new crankshaft end seal would be great, as well as maybe a new input shaft end seal. Don't spray it down with cleaner.
Also, grease the clutch fork pivot ball, and replace the throw-out bearing with new clutch.

Would some sort of industrial thinner maybe work better for taking off the thicker grease? ......Just an idea