[djh65]

06 ridden hard, oil never changed, air filter never cleaned. funny thing it started running bad. I checked the air filter for him and it was a mess, it looked like a dirt clod. So as I'm cleaning it my buddy looks into the intake and it is a mess. He cleans it out as best he could, should have removed and cleaned it better. Anyways the next day it started making strange noises and then would't kick. I took the top end off and the intake valve is bent. I'm going to take the head in to be fixed. Any other advise while it's apart? The cylinder seems to be pretty smooth.
David

[Asmith]

Might be worth doing a new set of rings and a piston inspection while you are in there.

Make sure the cause of the bent valve is determined (timing) before proceeding.

Also check the valve guide and valve seat very well.

[djh65]

Thanks. could a large amount of dirt cause it to stick?

[djh65]

So you don't work on the 100's?

[Asmith]

Thanks. could a large amount of dirt cause it to stick?

Most likely no. The valves are steel and pretty strong.

So you don't work on the 100's?

Sure. Send it down. We work on all bikes from 50's to 650's...but no Chinese junk.

[djh65]

You must not have got my PM. So what else should I check while you have the head?

[Asmith]

You must not have got my PM. So what else should I check while you have the head?

The piston for impact marks.

The rod for excessive play.

The pin for excessive play.

[djh65]

The piston did have a small impact mark from the intake valve. I guess I have to take the cylinder off and check that out. How much do yo think it will cost to redo the head?

[Asmith]

The piston did have a small impact mark from the intake valve. I guess I have to take the cylinder off and check that out. How much do yo think it will cost to redo the head?

Post a pic.

An impact mark means the timing jumped. The cause of that jump needs to be determined and addressed prior to reassembly.

[djh65]

I'll get one tonight. It doesn't look too bad but I guess any impact isn't good.

[Asmith]

I'll get one tonight. It doesn't look too bad but I guess any impact isn't good.

Yup.

Especially on a cast aluminum piston. Forged, I wouldn't be so worried but a cast piston is more likely to have internal structural damage causing it to come apart at an inconvenient time. (Like there's a convenient time for them to come apart.. )

[djh65]

I guess the best plan would be to pull the cylinder and replace the piston and it's bits. I will try to get the head in the mail this week. I'll leave the valves in place if that helps.