Hey, that's pretty good response time Paul - you couldn't get a job with most companies' service department, because you're too quick to get the job done. What used to be known as a "rate buster" in the labour movement.
I think the results are pretty conclusive, I just don't know exactly which bit is faulty. The 80 psi reading is what you'd get if the decompressor were working properly, and the 145 psi is what you'd get with no decompressor. What I don't understand is how the difference between decompressor and no decompressor is so spread-out: I'd expect a very sharp transition. I remember when my brother's Intek wore out its decompressor, it worked perfectly with the minimum specified tappet clearance, but stalled on the starter and burned everything out at 0.001" more than minimum specification. One possibility is that your decompressor mechanism may have gone a bit springy, perhaps due to wear in its pivots. You will recall I asked you to try to find out whether there is any compliance in that mechanism: whether if you push the pin inward, hard, with a small piece of metal, you can detect any movement. That would mean the mechanism wasn't pushing the pin as hard as it needs to, because of lack of rigidity.
