Topic: Uh Oh...

[SOHC4ever]

So, I'm riding along on my CB750F, right? Happy as a clam, nice day out, bike's running well, and out of nowhere comes this loud, obnoxious valve tick.
More like a valve CLACK.CLACK.CLACK.CLACK.CLACK.

I take 'er home nice and gentle, and when I open up the valve covers to get a look, I'm missing a lock nut on one of the intake valves. Not good. That lock nut was THERE a month ago when I set the valve clearance.

I called the shop and they suggested I pull off the sump pan and have a look to see if it's in there. It's not.

Any suggestions from the experts about where it might be caught? I'm going to assume it's not safe to run the bike in the interim.

Thanks in advance, guys.

Braden

[333]

Did you pull the valve cover or just the inspection caps?  If you just pulled thr caps, try the whole cover, You may find it.  I did this on my 750 also, except I didn't lose the lock nut.  I missed a shift and backed off a valve almost an 1/8 of an inch in a split second!

[Bodi]

Probably just sitting in the cam area. try looking around in there with a dental type mirror. If you see it, a magnet pickup tool should snag it.
Take the tappet covers off and have someone slowly lower the bike until it's lying on its side while you're looking in the holes and listening, the nut might fall into view.
This is one of those times when one wishes the rocker cover was removable in frame.
If it hasn't dropped to the sump than the cam area is about the only place it could be. There's a chance that if it does make it down from the top it could jam in the crank sprockets and chains or get kicked into the transmission - either would be unpleasant -so I would be worried about riding it.
The only thing worse than having your bike break during a ride is ruining the ride by worrying about it breaking.

[merc2dogs]

happened to me once, luckily the nut was right next to the valvespring and I was able to get it out with a hooked wire. reset clearance, checked the rest and everything was good. 
 So hopefully you have as good a luck.

Ken.

[Steve F]

Yep, happened to me too when I missed a shift at over 9000    The nut fell off, and the adjuster backed out so far that it was hitting the inside of the adjuster cap, and beat the inside of that pretty good.  The nut ended up on top front, next to an exhaust valve spring, and ALMOST fell down into the engine.  Was able to retrieve it after loosening the valve cover just enough to get at it with a magnet.  Check the area for bits of metal that may have been scraped off from the adjuster screw, and then change the oil to be safe.