I am using DL-50 on 50CC Edge 540. Configuration:
23X8 Xoar Prop
50:1 Mobil Racing 2T
The engine has about 80 flights.

4 months back when temp was around 36C@1800Feet it was revolving at 6400 rpm. Now during winter season temp 13C it is just giving me hardly 6070 RPM at the most. I have set the ignition timing at 29 4 months back which is still the same. Re tuned to get the rpms back but of no use. It is not giving me more than 6070 in any case. Did one flight even the power response is not good. Can someone guide.

When you said "retune", did you richen or lean it?

Yes as it gets colder and the air denser you will need to richen the needles a bit.

Unless you have other issues at work like spun bearings dragging the engine down. When one of mine went it gradually lost power until it lost about 600 rpm at which point it started to change tune all the time. When I disassembled the engine I found both crank bearings had were spinning in the crankcase.

Check end play at the prop hub and feel for roughness when pulling the prop through a few blades. Easier if you remove the spark plug when doing this. Pull the muffler and view the side of th piston looking for unusual wear. If anything feels or looks unusual call your dealer and discuss it with them.

If it's not a bearing then clean the carb screen and gas filters.

Yes, I second T.O.M.'s advice. I've had to clean my screen inside the carb twice now and I have have a screen type filter on both the fuel jug and in between the tank/carb. I am fixing to put a Hi-Perf small micron filter on my fuel jug, the screen just isn't getting the small stuff out.

Thanks for the tips. Today I again checked the engine played with the needles once again but unable to get the power and top-end 500 rpms back. Furthermore the engine was giving weired sound too.

I opened the engine and figured out the piston side bearing of the connecting rod was having some play. I have to figure out how to open the prop hub so that I can pull the shaft out to check the main bearings. I shall inform once I become successful in opening it.

Start at post #2817 and you can't go wrong.

http://www.rcuniverse.com/forum/m_64...13/key_/tm.htm