XS400 SOHC Bearings

[Dimitar]

Hi Guys,
I have a eurpoean version of the XS400 (model is 4g5). i want to do an engine rebuild, but i cannot find a set of main bearings. I have done a lot to the bike, it is in a state of restoration.
Thanks a lot for the help.

 

[xschris]

These are hard to find in any size and even more so in sizes for older/worn motors. They can be very pricey too. I would spec you motor to the size it will need as they don't wear evenly across the crank. Then search by OEM part numbers. These are the only motors that use these type plane bearings yamaha made.

 

[Bear Hands]

If the bearings and crank journals look ok its worth using Plastigauge (https://plastigauge.co.uk/) to measure the clearances, you might not need new bearings at all.
Con-rod bearing clearance is 0.021-0.045mm.
Main bearing clearance is 0.020-0.044mm.