Topic: How worried should I be?

[rugger81]

Before anything, let me just say that I have a stock 77 cb750k save for larger jets and pods.

So I took my carburetor rack off my bike today to change the jet needle clip setting when I noticed that a screw is missing from my butterfly choke valves.  Now I'm almost positive that it was there since the last time I took off the carburetors maybe a week ago.  I've only ridden the bike once since then, yesterday, and it ran just fine.  No strange noises, nothing.  I had just swapped out the jets, so I was taking it WOT upwards to redline  maybe a dozen times for about a 10 mile ride to try out the new smaller jets I put in.

Now common sense would tell me that a screw passing through the carburetors into the engine would make one hell of a racket.  Also, the carbs were off the bike for an hour or so and took a trip to the auto shop before I noticed the missing screw so it is possible it fell off then.  I don't really know what to do, so I'm not going to start the bike up again until I get your wise council  But what should I do?

[eldar]

Check the pod on the carb or all of them if you do not remember which one was on there. After that, check the innards of the carb and see if there is anything there. From there, check the carb manifold boots but be careful here as you could tip it into the engine.

[Sam Green Racing]

It's probably gone through the motor and is now lodged in the muffler.

Sam.

[eldar]

Do the valves open far enough for that? Besides having to fight gravity to get there?

[754]

No gravity involved, compression will push it thru if there is room.

If you can get a cylinder light, try to get in through plug hole and inspect.If it got into the intake port and is not lying on carb side of the valve, then 1 of 2 things happened.

It blew through or stuck into the piston or head, if it is the last, there is a really high chance it will come back to bite you if it dislodges. Now at high rpm, you cant do anything if it happens, at low it could lock your engine.

I had that lesson on a CB350 one winter day on snow, screw came out as I shifted and locked it up!! There is a reason the used to peen the screws..

[rugger81]

Ugh, thats the last thing I wanted to hear.  Well, there's less than a month riding season here and I'm thinking of doing a rebuild this winter.  So maybe I'll just wait until I can get the head off and inspect it proper.