CT90 | Crankshaft Bearings, Transmission Bearings and Engine Assembly

The inside of the engine on my current CT90 project was badly exposed to the elements because it was left sitting outside without a couple of the engine covers. I decided to pull the engine completely apart and rebuild from the cases up.

Crankshaft Bearings – I wasn’t sure what bearings were used for the crankshaft because the old bearings were unmarked. I contacted Jack @ DrATV.com and he sent me two new bearings. Turns out they are just an open #6305 bearing, that would be available from any industrial supply company. Since Jack had a great price I just got what he had. As for removal, you will need a shop press to remove the crankshaft bearings. Before pressing them off, be sure to mark where the teeth of the timing chain sprocket are lined up on the crankshaft.

Transmission Bearings – The old transmission bearings were marked, so I just ordered an open #6004 for one shaft, and an open #6204 for the other shaft. I’ve purchase from Grainger.com in the past and they had just the bearings I needed.

Engine Assembly – All new gaskets and seals were also gotten from Dr. ATV. The parts inside the engine cases are actually quite simple; there are only a couple big pieces. I’ve linked a video below where a couple people did a quick engine assembly at a Tech Day in 2011. If you’re a beginner, just curious, or need a refresher, here you go….


Men at Work – I snapped a couple pictures as I worked. Here is what my engine and workspace looks like at the moment.


Bloody brilliant work on a CB450. And on the video…

Pipeburn was started by two motorcycle enthusiasts over 3 years ago. Our mission is to provide quality motorcycle products without charging an arm and a leg. We sell only the best brands, the brands we personally use every day.