Vintage Dirt Bike Q & A

Does a 1974 CR125 barrel fit on a 1978 CR125 please?
Is the porting different. Will it give me different power caharacteristics.

What other early to late engine parts are interchangeable for my future reference?

many thanks

If I remember right the 74-75 cylinder will fit the 76-78 bottom end but the 76-78 cylinder will not fit the 74-75 bottom ends. The 76-78 cylinder sleeve (liner) is to thick not allowing it to slip in the 74-75 cases.
Porting is really the same (compare both cylinders) although the 74 cylinder does not have the boost port (also known as the GP cylinder) like the 75-78 cylinders do.

Power? Depends on what you want to do & what level your racing at!
Pipe, carb, head, porting etc. Most 74-78 CR125 motor parts are interchangeable but there are some parts that are not. Even the microfich for both of these bikes have the same part numbers on some parts.

The 74-75 CR125 air boot, intake manifold, exhaust flange will not work with the 76-78 CR125. 76-78 came with a bigger carb (30mm) but the 76 stuff will bolt up to your 74-75 if your running a larger carb or differen't pipe.

Hope this helps.