Mode 18 main bearings

In which case you may be able to get replacements from a bearing supplier eg Simply Bearings or the Vintage Bearing Company. The latter may even have details of the original fitment.

I'm led to believe they are 43/64" or 17mm wide but apparently no one makes these width bearings anymore.....I'm not sure how true that is....maybe someone knows differently

Have just bought a ball and roller bearing for my 1930 18 from Vintage Bearings. Perfect, you may wince at the price but you will not find them anywhere else.

Regards John.

If someone can provide the bearing numbers I will check my sources here in the States for availability.

Mike

These are specific motorcycle bearings hence their code. The ball bearing is a MC 22 and the roller is a RMC 22. Both have the dimensions of I.D 22mm, O. D. 50mm & width of 17mm. The roller bearing with  a shoulder in the outer race has a code RCRA 22. (These are Ransome and Marles codes) 

I did buy some here in Melbourne recently for my engine but the price was about the same as Vintage Bearings in Burton upon Trent.

There are common metric bearings with the same i.d. and o.d. but these are only 14mm wide. These can be used if the MC bearings can't be sourced if spacers are used to make up the difference in width.

this is what I've had done 14mm with 3mm spacers I wasn't particuarly happy about that I hope they hold out.....I'm going to check for the proper jobbies on Vintage bearings do we have a link to the precise ones anyone