MS-660

[Bink31]

I have a MS 660 that I did a top end rebuild on. During the build I check the connect rod and bearing in the bottom end and everything looked good. I put it all back together went to pull it and it popped like it was going to start after about 10-12 pulls it locked up on me. I tore back apart checked the connecting rod and it was jammed. I in jammed it put it back together and pulled it a few times and it jammed again. There was nothing broke inside the bottom end bearing in the connecting rod was good. So my question is what could be causing this to jam up? Any help would be great. Thank you

 

[Maintenance Chief]

The crankshaft off center? Bad bearings. What caused the original failure?

 

[Sagebrush33]

Check the case bearings.

 

[Wonkydonkey]

You don’t say where in the cycle of the piston or if it’s in the same place it’s locking up.

it could be the rings in a port, it could be the piston hitting the crank lobes.

it could even be excess fuel and oil at TDC

but as you say the conrod got jammed. I'd be pulling it over without the top end on and see & feel what’s going on. It could even be a bad crank bearing/s. As you never said why your putting a new top end on

these are just my thoughts to get you thinking of other possible issues.

 

[Lightning Performance]

TTT