Dropped Valve

[karatechop5000]

So at the end of last season, my bike was running fine. 2000 model with about 5,000 miles. I filled the fuel tank and put it in the garage for the winter. Occasionally I would start the bike to charge the battery. About midwinter, the motor locked up while trying to start. Turns out a valve "dropped" and jammed the piston. WTF? It really just doesn't seem fair. Anybody else "drop" their valves? Why did this happen to a nice guy like myself? Should I get a rebuilt head, or a valve job? I wish I knew why the valve dropped.

[gsJack]

Tight bucket + cold winter start = broken valve.  A number of members have had a problem with a tight bucket, fit too tight in head at factory.  Happens to the best of us, I had one also.    Bought my 02 in 9-03 with 4k miles on it and checked valves the next spring and discovered the tight bucket and decided to let it go to see if it would wear in and loosen up. The next Mar I checked valves again, still tight, let go once more, and a month later I broke the valve while I was cranking it to start on a cold around 32F morning.  Might never have broken if I hadn't been starting it in very cold weather.  The colder it gets the tighter the steel buckets become in the aluminum head and as the engine heats up it smooths out and runs good.

I pulled the head, replaced the broken valve and tight bucket, and it has been good as new for another 65k miles since.  Pull the head first and check the damage and then decide what to do with it.  My valve check log, bike has 85k miles on it now:

http://img.photobucket.com/albums/v443/jcp8832/GSvalvelogs.jpg

[viggen]

Stuff like this seems to always happen to the nicest people... (I should know...)

Luckily it's still march so you have plenty of time before you're missing the nice weather tinkering in your garage.  The haynes manual I bought has a pretty good description of how to take the engine apart and put it back together.  You can pull the head and even the cylinder block with the engine still in place.  As long as the cylinder bore and valve guides are not damaged, you don't even need to send anything out to a machine shop. 

I did new rings ($40 for a honing tool at harbor freight.. you'll also need a drill) and lapped in a new exhaust valve ($7 for a valve lapping tool at harbor freight, $10 for lapping compound at autozone) last summer during the nicest riding days of the year (DOH!!)  A torque wrench and some basic tools would also be required.  Good idea to replace the fuel lines while everything's apart too.  Buy generic line from a local motorcycle shop for a dollar a foot vice replacement suzuki lines for $10+ each.  Other parts can be figured out from diagrams on bikebandit.  Head and cylinder gaskets, etc, etc. 

I had never been that deep into an engine, but every time I start it now I feel just a little proud.  Better to learn on a $2k GS than on a $10k car!!  Good luck!

[karatechop5000]

For some reason, I thought these were non-interference motors. I would expect a tight bucket to kill compression or cause backfire; but not damage my piston. I made it worst by slamming it repeatedly and even trying to push start. Duh. I thought it was in the starter's engagement gears or the generator.

[gregvhen]

when ever i start it up after it sitting for a long time, i like to turn the engine by hand for a few turns first.  most of the time you wont be able to break anything by hand turning the engine as long you dont try to force anything

[karatechop5000]

Thanks everyone. I'm back in the saddle again. Gregvhen, I will always remember that advice.