SOHC.co.uk Forums > CB500/550

Crank bearings good or bad

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Bryanj:
In all honesty whilt i have heard of the needle rollers failing on 500 i have never actualy seen a worn out gearbox bearing

Acro1985:
Thanks again for all help and advice.

Although I was hoping someone wasn't going to say the needle bearing are like rocking horse poop.

I am missing one the little rollers for bearing on the main shaft (NR 15 on the part diagram) it fell off as I was taking it of the case to put into bag to keep everything together for the shaft and they scattered all over the floor. I have found 15 but the 16th has vanished 😭

Bryanj:
Try looking up a local bearing supplier and taking one needle in to compare, they frequently sell loose balls and needles

Acro1985:
Am I right in thinking you can no longer get the yellow crank bearings?? Having done some searching on the forum, and much head scratching, from the marks I can find on the crank it's 1A or A1 on at least three of the journals. On the others I can only make out the 1. Conrods are stamped 2D for three of them and 2C for one.

Sorry for all the questions this is the first motorbike engine I have completely stripped down to rebuild

McCabe-Thiele (Ted):
You are unlikely to need Yellows, as a starting point for your mains look at your crankcase codes, then accurately measure your crank mains in mm. If you use the search facility here there are lots of posts on the subject.

As Bryan said earlier check your crank first for any wear ridges. Beware of confusing conrod weight codes with crank web conrod codes.

PS The crankcase mains starting point codes are easily visible as they are stamped on the back of the crankcase, five letters containing A,B or C. It's extra confusing as the tables for the mains and Conrods use different axis in the parts book.

When web  codes are illegible you need to rely on a combination of micrometer readings and Plastigauge. It's always a bonus if the edge of your old shells have colour markings that are still visible - it's just a dab on the edge - the numbers stamped on the back of the old shells are just casting batch numbers so are of no help.

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