I have two of these .49 engines mounted in my twin. I have five tanks of 5% XP Sport fuel ran through each engine on the bench.
XP is 75% synthetic 25% Castor and 20% oil It was a really good beginning to a break in, very impressive. Both engines were primed and started on the first flip. I installed a counter rotating crank in one of the engines and it runs the best. Went to the field for the maiden flight and had all kinds of trouble. The counter rotating engine ran great, I mean excellent. The normal rotation engine would not start. Here's the deal,
The prime burned off then the engine would just quit so, I opened the low needle 1 extra full turn, prime burned off engine would quit, I opened the needle another full turn and the engine ran. I advanced the throttle slowly to wide open and it took a minute to unload and reach the 11k RPM. Brought the engine back down to idle and it would load up almost right away and quit. Repeated this process about 6 times 'till I finally managed to obtain a rich needle half descent transition. Started the counter rotating engine (first flip) and ran them both up. One was running 11.026 the other was running 11,046 very nice. Back down to idle and then back up, the counter rotating engine reacted awesome, the normal rotating engine struggled through the mid range till it hit RPM and they both sounded awesome again. Very nice stall turns could be achieved with this setup I actually performed the maiden flight here and landed with one engine out. The counter rotating engine brought her home.
I started to lean the bottom end out somemore to match and managed to get it quite close. Filled both tanks got ready to go again and the dang thing burned its prime and quit again. Started to open up the needle again and basically repeated above.
I'm at a loss ! What could change?
The clunks in the tanks are closer to center mounted in the fuse then they were on the test stand
The tanks are the same ones that I used on the test stand
I swapped glow plugs
I blew fuel through thinking it was debris
????
Any idea?
The counter rotating engine is running awesome, quite possibly the best break in and best transition that I have ever experienced. Very nice!