So I picked up a motor from a guy who had a small nut fall into his airbox while the filter was out.
The nut entered the combustion chamber and ended up between the piston and one of the exhaust valves stopping the motor and apparently bending an ex valve.
The piston has two small indentations on the same valve pocket where the typical crown carbon is missing from the impact. if you clean away the carbon you would not even see it. That valve has one very slight matching imprint on its face. That valve is not quite closing all the way. when you peer into the ex port you can see a little light at the seat. i guess it is bent and hanging in the guide. The guy tells me he took it apart as soon as it locked up and found the nut.
The cam journals and the other valves look okay. When i spray WD40 behind all the other valves I only see a tiny bit of dampness seep through after like 10 minutes. They look sealing pretty tight to me. Only one intake valve clearance is a little tight @ .003 the other is .004 and the unaffected exhaust is .008
The piston, cylinder look normal as well. Just a little skirt wear on the exhaust side as usual.
The Rod and crank feel fine to me. No up and down.
So.....what do I do?
Slap a valve in and call it a day, or send it out to be looked at? How can I assess the valve guide?
I really don't think the bike was run after the initial hit as there are only two small marks on the piston and one on the valve. i don't think it touched the intake valves at all.
What about the crank? This motor has little use on it and although I can, I'd rather not split the cases.
Opinions?
The nut entered the combustion chamber and ended up between the piston and one of the exhaust valves stopping the motor and apparently bending an ex valve.
The piston has two small indentations on the same valve pocket where the typical crown carbon is missing from the impact. if you clean away the carbon you would not even see it. That valve has one very slight matching imprint on its face. That valve is not quite closing all the way. when you peer into the ex port you can see a little light at the seat. i guess it is bent and hanging in the guide. The guy tells me he took it apart as soon as it locked up and found the nut.
The cam journals and the other valves look okay. When i spray WD40 behind all the other valves I only see a tiny bit of dampness seep through after like 10 minutes. They look sealing pretty tight to me. Only one intake valve clearance is a little tight @ .003 the other is .004 and the unaffected exhaust is .008
The piston, cylinder look normal as well. Just a little skirt wear on the exhaust side as usual.
The Rod and crank feel fine to me. No up and down.
So.....what do I do?
Slap a valve in and call it a day, or send it out to be looked at? How can I assess the valve guide?
I really don't think the bike was run after the initial hit as there are only two small marks on the piston and one on the valve. i don't think it touched the intake valves at all.
What about the crank? This motor has little use on it and although I can, I'd rather not split the cases.
Opinions?