ORIGINAL: BOUND_4_HELL
My ignition is running at approx 4 volts, one of things I have been meaning to try, is to install a two cell LiPo and a regulator, this would bring my voltage to 5.2. but I do not believe this is my problem it ran good with this same set up. However, one never knows until it’s tried.
That's possible cause #1 of the problem.
Try a 2-cell 1100mah A123. Put a 1N5003 (or 1N5004 etc) diode (Radio Shack) in series with the positive wire between either the switch and ignition cutoff or switch and ignition if you don't have a cutoff. The diode will bring the voltage down from 5.7 (full throttle) to 5.9 (idle) volts and can handle up to 3 Amps.
http://tweakshop.net/DL50-install/1.jpg
If you solder the battery pack yourself, you could use servo wire and use the yellow/orange wire as balancing wire. This way you can balance charge the battery through a switch with charge jack.
http://tweakshop.net/DL50-install/2.jpg
Edit: Same setup applies for the Rx battery.
http://tweakshop.net/DL50-install/6.jpg
I do not have a hole in the firewall and I do not relish the thought of doing so, as the fuselage would end up with fuel spit. The carb is 15/16 away from the firewall; it should be breathing OK, as I get a good static RPM of 7240.
If the ignition voltage fix doesn't work, I guarantee the problem is related to air pressure changes around the carb intake. Imagine the air pressure changes heavily during different throttle positions and positions and speed of your plane. Adding the volume of the fuselage to the engine box results in a much more consistent air pressure because it's leveled out over a larger volume. Simply add a thin coat of alcohol thinned epoxy to the inside of the engine box.