valve noise

My 98 XR250 has never had the valves adjusted. Slight noise but not bad. I adjusted to the wrong numbers (.005 int. and .008 exhaust) instead of .05mm and .08mm. Very noisy! I reset to .002 int. and .003 ex. as per my Clymer's manual. It's still worse than before. I disconnected the manual compression release to make sure it wasn't a problem. Did I damage something or am I just screwing up again?

make sure you are not getting mixed up with mm and inches

not sure on the specs for a 250 sorry

I think your Clymer manual is wrong. Specs should be .003" and .004" inch respectively, not .002 and .003 I believe.

Make sure you're on the right stroke, compression, when checking/making the adjustment.

Thought it was 4 ex and 5 in + or - 1

For an XR400 it is, but a 250 is 3 and 4 +/- 1.

Thought it was 4 ex and 5 in + or - 1

Per my factory 250r manual, it's .004 and .005

Something else to take into consideration:

Is the cam chain stretched? If it's at its service limit the bow tensioner will not keep enough tension on the chain and give "valve noise" indication.

There are also people that have had the rocker arms "pit" from the tappet point, but that is not as common as the cam chain stretching. With pitting, a flat feeler gauge will not give an accurate measurement (covers the "pit" when measuring)

Pull the valve cover, and you can visually check the cam chain tension. The tensioner should have enough pressure on the chain to not allow ANY movement.

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