valve adjustment problem

[gomert43]

Have a problem with a valve tappet.  Measured valve clearance, pulled shim, installed new shim, now valve tappet not returning all the way back up.  I have tried rotating tappet to different positions but still the same result.  The bike is a 2001 with 8200 miles.  The other shim I had to replace went without any problems.  Need help.

[D-Day]

Have a problem with a valve tappet.  Measured valve clearance, pulled shim, installed new shim, now valve tappet not returning all the way back up.  I have tried rotating tappet to different positions but still the same result.  The bike is a 2001 with 8200 miles.  The other shim I had to replace went without any problems.  Need help.

If you can rotate the tappet, it is not stuck.  Are you sure you didn't install a shim that was too thin?  Don't trust what they are marked, use a micrometer.  If you can rotate the tappet and you set the clearance correctly, then you valve could be stuck.  Check your compression, that will tell you if the valve is seating.

[Egaeus]

How did you hold down the tappet?  Did you rotate the engine with it down?

[gomert43]

I used the suzuki valve tool to depress the tappet bucket and did not rotate the engine.  The valve clearance is pretty much now off the chart.  If I remove the shim I can grab the bucket with tweezers and pull it up but it will go back down.  Checked shim size and found it to be true.

[Egaeus]

My hypothesis (not even a theory) is that your valve isn't seating properly like D-Day suggested.  Is it the intake valve?  I bet it is, and here's why (gathered from reading the last few months): 

Your bike has obviously been sitting in the past considering the mileage.  If someone stored it with the petcock in PRI, it's possible that the carb float(s) didn't seal, causing the carb to overflow, leaking gas into the intake valve, where it evaporated and built up varnish.  When you compressed the valve with the tool, you pushed it down further than it normally goes.  This allowed a piece of lose debris that normally couldn't fit between the valve and the head to get between them, causing the valve not to seat.  Of course, it's probably stuck to the valve or the head now. 

Of course, this is just a theory.  To make sure it's not seating, you'll need to test your compression after you've carefully made sure that your valve seats enough that it won't hit the piston by turning the engine slowly with a wrench.  You don't want a bent valve.  Once that's accomplished, you can do a quick thumb compression test.  While cranking the engine with the starter, put your thumb over the spark plug hole.  It should push your thumb off with a pop. 

Of course, take out the spark plugs before doing this, and make sure they're grounded to the engine and the boots are on them so that you don't damage your ignition system.  Alternatively, you can use a compression tester if you have one handy, or have always wanted one.  It won't be accurate without the engine being warm, but it'll give you a good idea by comparing your cylinders. 

[gomert43]

Egaeus, thanks for the ideas.  Finger testing compression tells the story. No compression in that cylinder.  The offending valve is the exhaust valve. Bike is actually 2 years old in riding time, I bought it as a leftover in 2004.  I will ride 12 months a year (depending on weather) so it has not sat idle to much, the last ride was first week of February.  Then it was time to tinker. Looks like the heads will have to come off to find and fix the problem.

[Egaeus]

More than likely then it's carbon causing the seating problem.  Good luck.  Here's hoping you don't have a bent valve.