TonyE

Thanks for the info. I don't have a gauge but I'll pick one up and test the carb. Found a good video showing how to do it with a WB8.

BTW, I'm not a motorhead. I'm trying to learn as I go. What is "pop off pressure" and how do I check it?

Responding in order... I removed the reed valve and it looks fine. I'm going to replace it but am waiting on a part quote. The prop is a ParaJet 3 blade. My motor is a ParaJet Volution 2 with an XT172 motor. No, I haven't checked the plug on each flight. It's been six months since I was able to fly and it didn't perform well on the first flight, so it's been grounded since then while I try to troubleshoot this. During the flight, it maxxed out at 6500 RPMs. I let off on the throttle to loase some altitude, then when I maxxed the throttle again, I only got 5500 RPMs. The top end RPMs have been very inconsistent. I have changed the spark plug three times now to be sure that wasn't the problem. In addition to the reed valve, I'm also going to replace the carb. I rebuilt the one I have but I'm running out of ideas.

I bought a used ParaJet Volution 2 Macro last year (it's a 2012 model). An injury kept me from flying much but it seems like it has never run well. I’m not able to get over 6500 RPM with it and even that seems to be inconsistent. That manual says to shoot for 7600 RPMs. I can run it up, get 6500, let it back to idle, then get 5500 when I run it up again. Here’s what I’ve tried so far. Replaced the fuel tank cap and fuel filter. Replaced the fuel line and put in fresh fuel. Rebuilt the carb with the OEM kit (Walbro 37c). Adjusted the throttle cable to ensure there was no slack or kinks. Replaced the spark plug twice. Had a friend check the compression. I don’t recall what it was but it remained the same each time which led him to believe there were no air leaks. Adjusted the high and low jets as well as throttle after each change. Checked the packing on the exhaust silencer. It's relatively clean and nothing is loose. Checked the resistance of the CDI and spark plug wire I’m at the point where I may have to replace the carb and/or replace the reed valve. I also read that loose packing in the exhaust system could cause problems. I’m getting very frustrated and don’t want to just start replacing things. We fired up my buddy’s Volution 2 and it ran right up to 8000 RPM. Since the high-end RPMs have been inconsistent (even when manually holding down the throttle lever), it's been hard to diagnose. Has anyone seen a similar problem and, if so, how was it fixed? Thanks!