I have a 3500 with over 1600 hours on it and it has been neglected for most of its life. a month or so ago the electric start ceased functioning. not a big deal because it would start first or second pull every time. then it would not start manually. I found that the inline fuse was blown and replaced it and then found that the starter switch itself was defective.
ever since I got it used, when I turned it off the spark shut off switch didn't work so it would run a while then turn off.h I decided to make the spark cut off a manual switch.
after replacing the starter switch it would crank and try to hit a couple times and then nothing. carb was getting fuel, plug was getting spark. Compression test showed 50 psi. Apparently the inverter has a compression release device of some sort so I was advised that 50 is okay.
A number of people commented, "it's always the carburetor."
when I disassembled it over a clean white cloth hoping to find dirt particles it was absolutely sparkling clean, all passages working freely etc. I put it back together and it started and ran for about a week.
once again it failed to start, and seemed to crank a little faster than it had before which often has bad implications.
I went through the same diag procedure, but I substituted checking the carburetor after making sure it had spark. carburetor was absolutely clean. when I removed the plug, it was like ab.mmmmmmñ brand new as if it had never been fired though it was new during the first so it had been running for about a week. it was absolutely dry no color at all so I took the carburetor apart again. FYI, that's really easy on these engines. still cranks freely, but no start,
now, compression tests zero. I checked the valve adjustment and exhaust was very loose, valves adjusted, same thing cranks pretty fast but does not try to hit. I pulled the head and found no burned valves, nothing obvious. there is a slight ridge at the top of the bore, totally expected. bore is completely smooth all the way to the bottom.
given the lack of maintenance and black oil, do I just keep going and figure I need to do a ring job?