Hi All,

I have a Pilot Laser with a DLE35RA, it was built earlier this year and has had maybe 8-10 flights. The first few flights were using a mineral oil and then I moved to a fully synthetic high performance oil. The engine has run perfectly out of the box with no adjustments at all until today. The engine starts fine as it normally would and idels ok, however at mid/high revs (5,000 RPM ish) its very lumpy, backfires and won't transfer to the high end when the throttle is all the way open. I have changed the plug (NGK6) and the result is the same, also tried adjusting the mix but no joy. The ignition is powered by a 6v Nim eneloop. Any ideas?

Just a guess but I would look close at the ignition system. Check wiring , switch, connections, the high voltage lead to the spark plug, any place where insulation could have wore through to the wire. Also check the sensor pick up, wire and magnet .

Not much to go on there. I would look to see what the voltage range of the ignition is. I think you are at the lower end of the range. Eneloop cells are also a low discharge cell. I would try a 2s lipo battery unless for some reason you have an older ignition. Fuel filters are also very important on gas engines, I consider them a must. Hobby filters don't filter well enough IMO, I hit the garden and lawn equipment department in the hardware store for filters. I also recommend running a felt clunk and filling the tank through a third line. At the end of a flying session keep a couple ounces of fuel in the tank. This keeps the flexible parts in the carb from drying out and becoming stiff. Even with that if my engine hasn't been run in a few months, I will fuel up, run at a high idle until fully warmed up and then let it sit for a 1/2 hour or so to let the new fuel soften up the carb flexible parts.

I like the low voltage idea. That will put you into "limp mode" that will make the engine act like it's got a fuel issue. You'll need to eliminate that possibility BEFORE looking for a fuel issue of some sort.

What adjustments exactly were made to the mixture on the carb?