Originally Posted by dboyd351
Have you checked to see if you might have an intake leak? I had a shop put a new carb on a trimmer one time and it did what you are describing - started and idled fine, but would not rev up. Turned out they had not tightened up the carb to the cylinder well (actually left a nut off), so it had an air leak. I tightenet things back up and it ran fine.
Thanks for the input. All seams tight with no intake leaks. I've done about all the tests I know of including pressure and vacuum for crank seals and compression. All ok. I've installed new carb, fuel lines, carb gaskets, filters and new plug all to no avail. I'm waiting to talk to Zama again regarding the low carb adj. I know where it is but can't find a screw to turn. If that's not it, I must be overlooking something as I don't know what else to check except coil but spark is good.