Crank movement - explains the knocking!

[alanscottj]

For a few weeks now I have heard a knocking noise coming from engine, scooter not as smooth as she usually is and today she started to run a bitty boggy. Because she started to get a bit boggy I thought that the timing might be out so I took the flywheel off to have a look, the varitronic hasn't moved at all but the crank has movement, when I wiggle it (holding the shaft where the woodruff key is) I can feel it and hear it moving

So, I am assuming one of the bearings has gone, or could it be that the front sprocket bolt on the other side has come loose? Would that account for the wobble?

[rosscla]

Which way is i moving in and out or up and down?

[holty]

you should be able to turn the crank but you should not have any up and down or side to side movement, other thing to check for is any play between the piston and the crank, which would indicate big end or little end wear.

[mick1]

It's all guess work till you split the engine apart.

The front sprocket shouldn't cause play on the crank. I'd be more looking at one of the bearings (mag or main) with an outside chance it could be the crank itself.

oily hands and a few curse words should get to the bottom of it...........

[alanscottj]

Which way is i moving in and out or up and down?

Both! In and out and I can wiggle it left/right!

[alanscottj]

It's all guess work till you split the engine apart.

The front sprocket shouldn't cause play on the crank. I'd be more looking at one of the bearings (mag or main) with an outside chance it could be the crank itself.

oily hands and a few curse words should get to the bottom of it...........

Looks like it'll be getting opened tomorrow

[rosscla]

Bearings are certainly knackered I'd say.

[alanscottj]

Bearings are certainly knackered I'd say.

Yeah, I thought as much. it's lucky I enjoy stripping and building engines

[alanscottj]

Stripped engine this morning. Looks like drive side bearing knackered to be honest when I spin the bearing with my fingers and try and move it it feels ok, no movement at all but with the crank in place, the cranks moves like this :

Click on image for video

[HxPaul]

To be honest,that looks pretty normal