Screw fell in engine.

[Bspring]

I am thinking of buying a 400EX cheep but the problem is that one of the screws for the butterfly valve in the carb came out and was sucked into the engine. The engine appears to run fine. My guess is that it just pecked up the piston and the head then made its way out the exhaust. Is there anything to worry about if the engine is running okay?

[Trevor]

How long ago did this happen ? Has it only ran for 30 sec after this happened or did this happen months ago and the motor has been working fine sence?

[wilkin250r]

First off, you need to be sure that the screw is not still in the engine.

If the screw made it's way through, there are only a few areas that could really be a problem. It could easily damage the valve seats if a valve attempts to close on the screw. Or, it could scratch up the cylinder walls.

A compression check should tell you quickly if you have a damaged valve, valve seat, or problems in the cylinder walls. If the compression is good, then you're probably good to go.

[aviator4]

I agree with Wilken.

I would be too worried about the piston and sleve, those can be replaced fairly easily. If you have head damage, thats a bad thing.

Head work can get really expensive really fast.

It also depends on what "cheap" is.

[Bspring]

All good points.
Thanks.