Yamaha 50hp 4st breaking crankshaft

[cameronke]

I recently built from cannibalised parts a Yamaha 50 4stroke.

The original engine the bottom half came from had broken its crankshaft so I fitted a different power head (originally a Mariner but same as Yamaha) I used the Yamaha electrics.

Rebuilt engine ran great on test in garden. But after about ten minutes running at sea on Friday it too would appear to have broken its crankshaft. It would appear (though I have not stripped down to verify) that it is at the flywheel end.

I can think of no common problem that could cause a leg and gearbox to break two crankshafts. Anyone any ideas or experience?

Thanks in anticipation

Cameron

 

[PIGLETSDREAM]

try this website, very useful

http://www.marine-power.co.uk/


go to the help forum

 

[Lakesailor]

Try iboats forums This link is the result of a search on crankshafts in the Yamaha forum. You try it again in the Mriner forum.
Some of our cousins ask questions in a wierd way, so you need to trawl the forums a bit and form your own opinions.

 

[cameronke]

Many thanks

Cameron

 

[Lakesailor]

I see the link has time-expired now
this will get you to the front of the forums http://forums.iboats.com/forumdisplay.php?f=4

 

[cameronke]

Cheers Lakey

Cameron