mc5 250 info

[chicagojerry]

hi all, i'm trying to help diamond don out by fixing his mc5 250. its a 78 i think. originally i thought that he just needed a better shifter shaft which i had. when i pulled the motor out of the frame it was very evident that the motor mount bolts had come loose at one time. the front cases in particular are worn bad from vibrating in the frame. my questions are
1) how are these cases different from earlier models?
2) does anyone have a bare set that they want to part with?  
thanks for any help. chi jer

[454MRW]

In 1978, KTM revised the transfer ports leading up to the cylinder to a more squared off slighty larger version with corresponding tranfer ports in the cylinder, and porting that broadened and flattened out the torque range. Earier cases can be opened up and port matched to the later cylinder if needed. I am not familiar enough with any other internal changes for comparison. Gary Ellis has had my 1979 MX-6 250 cases welded up in that area to repair badly elongated engine mount bosses. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S

[Mike Lenz]

The cases are the same 76 on as far as all the mounting holes go.