I've been dreading the day I'd actually need to post in here, but I've done something real stupid, but if you can help me diagnose some possible problems that would be much appreciated 

After watching a youtube video a billion times on how to do a valve adjustment on my GS500E, I decided I was ready. Everything went smoothly until I needed to get the shim out. I decided not to buy a shim tool since I figured it'd take 2 weeks to get here and I saw plenty of posts on the internet reading "I took the cam off! no problem" but for me, not having that part of the process laid out to me proved fatal. I took the cam off, popped the shim out, replaced it, and then realized I didn't know how to get the cam back in. I left it in the chain, I just sat it down about an inch from it's original location, I didn't want to have to reset the chain. So at this point, I have no concept of a chain tensioner, so I try to pull the cam back in to place, like an idiot. Went back to my comp and checked the internetz, learned a thing or two about the chain tensioner, then I had no problem getting the cam back in place! So I decided to hand crank the engine a few times to get the shims feeling at home, and I met some serious resistance. You may wanna brace yourself, I cranked through the resistance, hearing a loud metallic crack like noise...

I decided the only thing that could be different is my chain, so I checked it, and there were a bout 21 links between the two cams. I read something briefly describing that there should be 18, so I took the cam back off and adjusted it, to get it to the right number of links and oriented in the right direction relative to the other cam. But I realize now the damage was already done by then.

What did I break? 

I would guess you broke a valve stem.

Your mistake was taking the cam off. You dont have to do that to change shims.

If I were you, I would pull the head and inspect it on the top and bottom. If you do need a good head though. I have one here that is complete and ready to run. But I would check yours first.

Seconded on the broken valve. Take a look at this: http://beergarage.com/GSTiming.aspx

You may be able to see the broken valve sitting on the piston if you remove the plugs and peek in. Also, if you remove the cams again and one of the buckets comes up further than the others -- that's your broken valve.

Remember -- don't turn the engine over until you get it out of there if it is in fact the problem. If you're lucky, you'll only have to replace one valve and the head gasket.

When I did the same thing I had lots of difficulty getting the cam chain back into the correct position and tension.

After setting the correct number of links between the cam gears and tightening the journal bearing cap bolts I would crank the engine over by hand. First I experienced resistance as the cams pushed down on the shims, then the whole lot would turn over very quickly with a loud "Clack!" noise. Every time this happened the chain had jumped a few teeth on the camshaft sprockets. I persevered and eventually it worked without skipping.

The noise you heard could just be the 'clack' of the whole mechanism turning over very quickly and jumping some teeth on the chain. On the other hand if you didn't set the chain correctly in the first place then you might have damaged the valves, as mentioned above.

Edit: Do you have a workshop  manual? (For example Haynes of Clymer.) If not you should buy one immediately before touching your engine again.

Quote from: weedahoe on January 18, 2013, 07:58:44 PM
Your mistake was taking the cam off. You dont have to do that to change shims.

If I were you, I would pull the head and inspect it on the top and bottom. If you do need a good head though. I have one here that is complete and ready to run. But I would check yours first.

No, the mistake was forcing the engine to turn over when it doesn't want to. I personally remove the cams every time I do an adjustment.

Quote from: angusgst on January 20, 2013, 11:02:52 PM
When I did the same thing I had lots of difficulty getting the cam chain back into the correct position and tension.

After setting the correct number of links between the cam gears and tightening the journal bearing cap bolts I would crank the engine over by hand. First I experienced resistance as the cams pushed down on the shims, then the whole lot would turn over very quickly with a loud "Clack!" noise. Every time this happened the chain had jumped a few teeth on the camshaft sprockets. I persevered and eventually it worked without skipping.

The noise you heard could just be the 'clack' of the whole mechanism turning over very quickly and jumping some teeth on the chain. On the other hand if you didn't set the chain correctly in the first place then you might have damaged the valves, as mentioned above.

Edit: Do you have a workshop  manual? (For example Haynes of Clymer.) If not you should buy one immediately before touching your engine again.

uh...the chain should not jump at all when turning it over...might want to check your timing...

Graham