MC-5 porting ?

[rowedder]

Can any one tell me if the porting specs are changed from a 1975 250 barrel to the 1976 MC-5 250 barrel or are all the 250's the same. Thanks much Dennis.

[James]

Hi Dennis. I spoke to you at Phoenix-we talked about your 250KTM and our  440 Maicos. I can not clarify porting differences, but EVERY MC-5 I have ridden is quicker than my old 75 250. If you have a 76 barrel you can run-you should try it. Remember also- this same 250 engine was used up to 1980. I am sure Dane could tell us what porting differences were between years. James

7" and 4" travel? Hmm-that makes 11" Hey! I can live with that.

[Mike Lenz]

A while back, since I had most the parts books I did some part number research on this issue. The cylinder liner part number changed in 75,77 and 80. Heres what the changes were I THINK. 75 went to a winged exhaust port. 77 went to a fingered intake port (like the 400). 80 went to a three fingered boost port.

[Mike Lenz]

By the way you cant strictly go by the year here. Thats when the parts book changed. Its my guess the changes actually happened sometime in the 74, 76 and 79 model years. Also exhaust pipe design got ALOT better in that time frame which would have helped as much or more than porting.