I am not trying to start an arguement but I know for a fact that the Webras run just as well loaded down. We have Webra 50s running 12.25x3.75 props on three different funfly's and all perform excellent on 15% fuel so the choice of prop is not the problem here.

We had one of our Webras doing the same thing and all it took to fix it was properly adjusting the low speed needle. Webras are extremely sensitive to the setting of the low speed needle. If it is to lean it will cause the engine to die and if it is too rich it will cause poor tranistion in the midrange. This is the price you pay for high performance. At least they seem to not need any adjustment for a while once are set right. It took me three tanks of fuel to get my last Webra correctly set and has been a gem ever since. Also there is no need to run the expensive #8 plugs in these engines they like the cheaper A3 plugs just as well.