Vintage Dirt Bike Q & A

anyone know if you can use a cr 250m piston in a mt 250?? the piston pin looks the same but the ring pins are not in the same place..

What year CR piston? I am pretty sure I have CR pistons from 1973-1976 and the rings are thinner in the later models but still in the same place.

All of those interchange with the MT250 from 1974-1976 with only the rings being a problem.

the cr piston is 74 and the mt is 74 as well. the cr ring would be a problem???

Check carefully.
I think the '75/76 pistons have a slightly relocated ring pin to clear the extra rear cylinder port.

thanks checked the piston again it was a 75 found the piston out of my 74 and the ring pins are in the same place as the mt only the cr rings are thinner would that be a problem?

Ring thickness shouldnt worry you so long as you use the correct rings for the piston.ie dont use thin ring in thick piston

I have both '74 and '75 CR250's.......pistons look the same at first ........but......the '75 has a slightly different ring pin location.( in mine anyway)

I do not know If the MT cylinder changed over the years........if not then I think either piston would work.

The '75CR cylinder gained an aditional rear transfer port which nessitated the slight repositioning of ring pin to prevent ring ends popping into the port.