Valve Adjustment Gone Wrong

I tried to do my own valve adjustment last weekend. Everything seemed to go fine until I tried to start the bike back up. It runs alright with a pretty steady idle, but it makes a terrible noise now. It sounds like a loud clattering from the valvetrain that is much louder than the ticking normally associated with valves.

Has anyone ever had this happen from setting the valves too loose? I added 0.025 - 0.075 mm of clearance to some valves, so I wouldn't expect it to make so much of a difference. I double checked the timing, and I made sure my manual cam chain tensioner was snug.

Update: I tore everything back down, and did another clearance check. All of the intake valves seem to be in spec, but some exhaust valves are too loose. I think the angle to get at the exhaust valves gave me trouble, and I ended up with bad measurements the first time around. I bought new feeler gauges this time that are pre-bent. I also loosened my manual cct a couple of turns to take any tension out (manual says to loosen cct).

The worst one was exhaust valve 4B. I measured it as 0.381 mm when the spec is 0.28 +/- 0.03 mm. I think the problem there was that I misread the shim at 180 instead of 190 because it was very faded. Another mistake I made was that I tried to bend my feeler gauges myself to get better access. I'm pretty sure the bends I put in created extra resistance that threw off my measurements.

Update #2: I am pretty sure I didn't wreck my bike!

I made all of the shim changes based on my revised measurements with the bent feeler gauges. I also ordered a cheap micrometer to make sure I did not misread another faded shim. I started it up after everything was back together, and.......it made a bunch of noise. The noise was different this time. It was more like the loose cct that I was familiar with. After twisting the cct another full rotation, my bike was finally sounding like it should again.

Thinking back to the noise it made after the first attempt, I think I was hearing cct noise and excessive valve noise. It could have been mostly cct noise, but I wouldn't have found the 0.1 mm out of spec valve if I didn't open it back up.

Lessons learned to hopefully help someone in the future:

The exhaust clearances are hard to check with straight feelers. The thicker gauges don't want to bend at the necessary angle.

It is worth it to have a $20 micrometer on hand. Some shims will probably be faded to the point that they are hard to read. Guessing wrong means that you are going to be taking everything apart again.

The cam chain makes a lot of noise if the manual cct is one turn loose. It can be hard to distinguish from valve noise.

Adjusting valves can be a humbling experience for an amateur mechanic, and can take up two of your weekends if you get it wrong.