In answer to several of the questions posed giving me avenues to explore (which is why I posted in the first place - THANKS!):
Finally did a P/V test - tight as a drum
Compression really is that high - read even higher (170 psi) with my "optimistic" gauge
Fuel lines tested by attached MityVac at one end, clamping the other end - no leaks
Agreed that "lightly used" is somewhat speculative but I know the owner and the overall condition of the unit (practically like it just came off the store shelf) makes me pretty confident in that assessment
Now for the latest news. I think I've found the primary issue and have to confess I was not careful enough in an earlier examination. Like several of you, I suspected some sort of air leak not allowing enough vacuum to pull fuel through the main (and only) jet. I took another look at the choke plate and its seal to the carburetor. Everything looked good and snug until I turned the unit upside down and saw that the plate was slightly warped and was ~1mm away from the throat, enough to greatly reduce the vacuum in the venturi. While I explore the chances of finding a replacement choke plate, I used my heat gun to bend the plastic enough to almost entirely close the gap. I now have to wait long enough for the unit to be in a "cold start" state to see if it fires in 1-3 pulls instead of 5-7 which is the best I've achieved so far. Fingers crossed and will report back when I have some news.
Meanwhile, thanks again for all the helpful tips and general wisdom shared here.
Finally did a P/V test - tight as a drum
Compression really is that high - read even higher (170 psi) with my "optimistic" gauge
Fuel lines tested by attached MityVac at one end, clamping the other end - no leaks
Agreed that "lightly used" is somewhat speculative but I know the owner and the overall condition of the unit (practically like it just came off the store shelf) makes me pretty confident in that assessment
Now for the latest news. I think I've found the primary issue and have to confess I was not careful enough in an earlier examination. Like several of you, I suspected some sort of air leak not allowing enough vacuum to pull fuel through the main (and only) jet. I took another look at the choke plate and its seal to the carburetor. Everything looked good and snug until I turned the unit upside down and saw that the plate was slightly warped and was ~1mm away from the throat, enough to greatly reduce the vacuum in the venturi. While I explore the chances of finding a replacement choke plate, I used my heat gun to bend the plastic enough to almost entirely close the gap. I now have to wait long enough for the unit to be in a "cold start" state to see if it fires in 1-3 pulls instead of 5-7 which is the best I've achieved so far. Fingers crossed and will report back when I have some news.
Meanwhile, thanks again for all the helpful tips and general wisdom shared here.
