Bad vibrations!

[Simo63]

Did you replace the crank pin when the crank was rebuilt?  If so was the replacement crank pin the same weight as the original?  Some crank pins are solid and others are hollow.  If you mix the two you're going to get some horrible vibrations as I found out years ago back in my road racing days.

[D project]

Pulled the motor down again to find that the loctite had not worked to hold the bearing in place.
I could get a feller gauge in between the bearing and casing.
I was able to locate another set or cases (thanks Bahnsy!) and have run with the motor and all seems well!
So conclusion was too much main bearing clearance in the cases
Thanks for all the input!

[Mick D]

Pulled the motor down again to find that the loctite had not worked to hold the bearing in place.
I could get a feller gauge in between the bearing and casing.
I was able to locate another set or cases (thanks Bahnsy!) and have run with the motor and all seems well!
So conclusion was too much main bearing clearance in the cases
Thanks for all the input!

Bearings are pressed or shrunk into a tight hole, at the end of the day it is still called an interference fit. with the right tools measure the hole, it shall or should be always smaller than the bearing OD, It can be felt in a hand operated press as "resistance". No bearing or body likes a loose hole.

[matcho mick]

http://www.youtube.com/watch?v=dq6T5BojXc8

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