Topic: engine 400/4 1976

[steven400/4]

ok peeps i just rebuilt my top end i had an oil leek from some where so i just started it up it ran soon as fuel got into the carbs i rev it and there was 1 small pop from the engine then i noticed oil all over the floor i noticed the oil filter was loose but i never touched it on the rebuild at all the thread on the bolt is stripped so could the pop i heard been the bolt popping out is if could there be anything i,ve done on the rebuild to corse it to happen

[bryanj]

If you only had the top end off no but if the bolt is stripped you have big problems as the threads are not repairable so new cases.
Having said that did you have the alternator cover off whilst you ran the engine?

[steven400/4]

no just the the head rocker carbs and exhaust

[69cb750]

Remove oil filter bolt, inspect bolt and case threads.
Replace bolt if threads damaged.
If case threads are damaged a tap can be used to repair (somewhat) depending on damage.

[steven400/4]

any idea what tap size it would be

[Flyin900]

The oil filter bolt is a M20 X 1.5 TP and if the case is damaged beyond a tap repair then a Time Sert kit will offer you the ability to rethread the hole back to the correct size. Downside is the kits are not cheap usually a few hundred dollars, so another option maybe a machine shop to do the repair. Since it is an area that you will be removing the filter bolt on a regular basis forget a HeliCoil IMO. The Time Sert is a totally different process in repair technology and permanent once it is installed.

I have had too many bike projects with PO installed Helicoils that have unwound with the bolt when removing said bolt for a restoration. Others may disagree, so there you go with another suggestion.

[69cb750]

any idea what tap size it would be

Post photo of bolt, case, advice will come.