I used some valve lapping compound on the leaky decomp valve and cleaned it out with carb cleaner and lubed it a tad. I pressure tested it and it seems to be good now. I'll keep it for a spare and test it in a cylinder next time I pressure / vacuum test a saw with a decomp in it. I know the used one I put in this saw held pressure and vacuum during testing no problem. I would think these would be somewhat self healing since it gets hammered 9,000 times a minute while you're cutting wood. I have read that peak pressure in the combustion chamber of a saw can reach upwards of 2,500 psi. But I don't have a whole lot of experience with them as "good" or "bad".
I don’t really know either I know they work till they leak then they get replaced. It will be interesting to see weather these can be salvaged or not
Not sure about salvaging one but I took one apart to thin the shaft to bleed off more pressure and deepen the detent groove to make it harder to pop closed. One of my ported saws has 240 psi compression and the decomp would pop shut as soon as you started to pull. I "tuned" the decomp so it stays pushed in upon pulling and blows 135 psi. Easy to pull and still closes tight upon firing.
Know I understand I was thinking you where trying to salvage an old valve out of a saw you where restoring. Know it makes sense on what you where doing
Compression was 180 on my cheapo tester that you have to hold on the cylinder, hold the saw, and pull the thumper cord. This was with 2 tanks of mix through the saw so far and I'm sure the new caber will seat in a little better with some more run time. I'm just happy it runs better than before and feels strong.
Got out today in between mowing to play a little. 12" Poplar blow down. https://youtube.com/shorts/Cy3hKtlY4OY https://youtube.com/shorts/NAMPe3F5
