Hi,

I'm a 30+ year modeler and not at all new to engines and tuning and have successfully run many types. I am not a needle tweaker (I don' t overdo it....) and have a tendency to be successful with engine performance and longevity.

I have a new Webra 145 AAR on a Zen 120 with which I am trying to get back into pattern and am practicing intermediate. This is a powerhouse and I have no complaints with idle, or full power capability.

I test ran the engine twice on a stand with it in the upright position and using a full length macs header and greve pipe.
(Piedmont package) Engine ran great .

Last Thursday were the first flights in the Zen....fantastic power.
4 flights..... Friday 4 flights....

However: Saturday 4 flights, but one had to be aborted due to engine reduction to half power even with throttle full open....engine didn't seem to be loading up and ran fine through landing....it would just not accelerate to full RPM. I leaned the low speed mixture, checked the hi-speed and flew the rest of the session. Sunday....3 flights and another flight went to half power after flying 1 intermediate routine. (I usually fly 2 or 3 per tank...3's pushing the fuel limit.) Again I leaned the low speed and the hi-speed a little and flew the rest of the session. Today...Monday 3 flights....same thing. I had set the engine prior to every first flight trying to make sure I'm not running it lean. (I don't need every ounce of power for the Zen 120.) The thing I find is that sometimes I can richen the hi speed by 1/2 turn without any change in the tach. (7680 on an APC 16-14, macs header cut to Piedmont specs for the Greve pipe) Yet then I throttle back to half momentarily and try to transition to full, sometimes the engine will not lean out at all (stays rich and loses more rpm....) I have zero experience with pumps so I don' t know if that is a contributing factor. There aren't any instructions in my box concerning the pump (except in German) so I have intentionally left it alone. As far as I know I have followed Piedmont's directions to the letter including leaning the low speed until the engine wouldn't idle and richening 1/4 turn. The engine transitions excellently from idle to full....I only have trouble when I back off the power to about half...and even then not all the time....just on occasion.

Any suggestions from anyone running the Webra 145 AAR (red head) are appreciated. (I now have 21 runs on the engine including the 2 break in ground runs. I'm using 15% Omega fuel, and the OS "F" plug.) I love it except for this reliability issue, (which is probably due to my inexperience with pumps.)

Thank you,