Calling all 1987 CR125 Experts

The other difference is the port placements in the two cylinders. They units will bolt up ok, but the ring ends on the two pistons are located differently and they will hang in the cylinders if cross matched.

Paw Paw

That’s great information. I’ve been looking for some information on this subject. I recently bought a spare cylinder and head, supposed to be from an 87, but I’d like to maybe use it on my 88. I’ve been trying to determine what year the cylinder is. Is the difference in the port placement pretty obvious, or just small differences? Any telltale differences between them visually? Thanks in advance for any advice. I’ve been debating as to whether I should keep the cylinder or sell it.

Didn't they switch from steel sleeve to nikasil in 88?

No, that switch was made for 89. 88 still had the borable sleeve.

The transfer ports are placed differently and thus causes the piston rings to hang on the rear stator side of the cylinder when using 88 cylinders on 87 engines. Take note of the piston ring end gap pin location to see the difference.
Back in the day there was a recall on the 88 cylinders from Honda and they just gave all bike owners a new cylinder and left the old one out in the field. Many tried to use the old ones on 87 bikes and ran into this ring end catching on those ports after only an hour or two of running.

Paw Paw