Vintage Dirt Bike Q & A

hi
i have a mr250 motor and i was wondering if a mt250 barrel will fit.the mt barrel is ported for flattrack.as i already have a running cr250 and i have a spare pre1975 speedway springer frame it could go in but i need the exhaust to be the same as 73 74 cr and mt to pass for pre 1975 racing
cheers
jim

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Jim Garvey
1x honda cr250m 1973 in bits
1x honda cr250 champion dirttracker
1x yamaha tt500 dirttracker 1976
1x yetman triumph dirttracker
1x tt500 longtack speedway bike
1 x 1940 350 ariel speedway bike
1 x bultaco astro grasstrack bike antig

MR250 cylinder will not work on the MT250. MT250 cylinder mounts like the early 73-74 CR250 using long mounting bolts for both the head and the cylinder. MR250 mounts on short studs on the bottom end. Also the exhaust exits on the opposite side. The MR250 cyl. will swap with the 75 and 76 CR250.