Excellent - thanks for the link to the parts. Guess I'll have to read up on that sticky about ordering parts from there.
It's amazing - the little currency conversion thingy says the pair of valves costs $4.68. I waste more money than that in
vending machines for cryin' out loud.
Re: the compression testing - when the issue first occurred, that is, when it wouldn't start after the throttle sticking, I could hear 'chuffing' back thru the carburetor while trying to e-start it. At that point, the carb was on, but the airbox connector tube was disconnected and pulled back so I could see into the carb. That sound is what first made me go get the compression tester, because the sound indicated to me a leaky intake valve during compression stroke. I was originally thinking I'd fouled a plug or wasn't getting gas or something simple.
So, first test was with carb on - one time with throttle wide open (and no choke) and repeat check with throttle slide completely removed!
And, 'cause I'm anal that way and this IS a cheapie Harbor Freight compression test kit, I went and tested my Yamaha XT225, just to be sure the gauge & tubing was working right and got 135psi or something high up like that.
Once I got the engine out on the bench, I used a big battery charger and ran the e-start and rechecked the compression while watching right in the intake port - no carb or even intake manifold. Same thing at ~30psi.