VBC1 Crank Mystery

Hi All,

Ive opened a VBC1M 3 port engine with serial number 430711.

The flywheel side crank caged needle bearing measures 38x29x15mm.

I can’t seem to find a replacement on the SIP website. For this model, SIP carries a 38x25x15mm caged needle bearing.

Can anyone explain why this engine has an odd crank size?

I am thinking to replace the crank and bearings. I’m hoping that the Mazzucchelli 45000000 will fit using a 38x25x15mm bearing. Has anyone else tried this?



Most Supers use 2 x Ball bearings on the crank ala VBA / VBB however really late versions changed to run what we would call a P125X / P150X crank, flywheel bearing and flywheel seal arrangement. The measurements you give seem to be the same as a PX (29 38 15, bearings should be measured ID OD Width) so try looking at the PX type.

Thanks!  I got it sorted!  Replaced the crank with Mazzucchelli P/N 45000000 and matching 38mm OD bearing.