Decided to try a smaller carb. and had a brand new ZAMA, C1M from a Poulan chainsaw (the Poulan people tell me the venturi size on this Zama is 8mm & throttle bore is 14). I tapped it for the pulse line and stuck it on. (I made a mistake earlier thinking the Walbro I was using was 11mm but it was 13mm). I was able to get higher rev's but still couldn't get full throttle so I took the carb off and put the spring in the pump and also mixed up some more fuel. Started out the same but after running for a few minutes and fluctuating the revs it came alive and went full throttle. Seems the engine was not fully broken in and I noticed all along that the exhaust was pretty black indicating to me that the ring was still breaking in. I got the tach out and was able to push the engine to 7300 rpm. and this is with a 20x10 MA wood Schimitar prop. I had to take a break at this point. I'll start her up again and see if it gets any better. Still want to do a little tuning to make sure it doesn't stall when the throttle is released. So far it just slows down to a nice putt,putt,putt.