2 cycle compression ......
 

Steve B wrote:
I have a 21cc hedge trimmer. A Craftsman. It hasn't run for a while, but
the guy swore it was running when put up.

I put new gas in it, and checked the obvious. It needed a new on/off
switch. It has spark. I can't get it to pop, even with shooting a little
gas into the carb, or on the sponge air cleaner.

When I pull the start rope, there isn't very much "POP" at all. I mean
resistance that would come from good compression, or from firing and
igniting the gas/air mixture.

Just how much "POP" should be present, even if you have the switch off, and
aren't trying to start it, but just basically see how much compression it
has? I call "POP" that instantaneous resistance on the pull rope where it
would hit TDC, or fire with a spark. Does two strokes not have the "POP"
that four strokes have because of their different configuration?

Tomorrow, I'll pull the carb and see if there's anything obvious there. The
primer bulb worked, no leakage, and filled up, presumably feeding gas to the
carb.

Steve



I've messed with a lot of the trimmers. Most of them now days are not
for this world long. Keep messing with it and you will get it running
but don't expect to much. The carbs are set to run as lean as possible
nowdays with very limited adj to richen them, which is why half of them
have to be run with the choke partially on.
Any chance someone ran it without the oil mixed with the gas?