Ok guys, got an issue that I can’t get figured out. It would be much appreciated if I could get some input on it.

I have a BME 50 that was bought used and came with some baggage.

First issue was that it had a CH ignition with the external grounding strap, which is a great ignition, but the plug boot was pretty worn out. I changed the plug boot to the metal cap style. I tested the ignition and all worked well.

The second issue was that the carburetor that came on the engine was a HLIC brand, which is not the stock carburetor (WT-201b) normally used on the BME 50. Being that this engine has some miles on it, and not really having a good idea of the history of the engine, I figured that the carburetor would need a rebuild. So instead of tracking down a rebuild kit, I decided to mount a DLE 55 carburetor (NIB, WT-664A) that I had lying around. I set the needles to 1.25 low and 1.5 High prior to first run.

First Run: Before I had got the parts in to fix the CH ignition, I ran the motor with the WT-664A carburetor and an RCEXL ignition. The motor ran great, transitioned well, good top end power (7300 rpm with a Xoar 21X8), but I noticed it had a slight miss at WOT. I did adjust the needles during this run. Ended up being about 1.5 turns for the low and 1.75 for the high.

Second Run: CH ignition and the WT-664A carburetor installed. Motor started fine. I let it warm up for about 2 minutes. After warm up, I went to throttle up and the engine started missing pretty bad and would not obtain full throttle without dying. After couple of restarts, I realized that this was not a tuning issue, but an ignition issue. One more attempt to restart and the motor would not fire. At this point, I figured that I did something wrong during the plug cap install and had fried the ignition. I brought the airplane back into the shop, and started to troubleshoot the ignition. Come to find out, the ignition tested fine, but the halls sensor had gone bad. I ordered another halls sensor, installed it and tested the ignition. Worked like a champ.

Third Run: CH ignition with new halls sensor and WT-664A carburetor installed. Started fine, top end was still good, but the transition sucked. If the engine idled for more than a few seconds, and you tried to accelerate the engine quickly, it would die. No stumble, no cough, just die. If you cycle the throttle from wide open to idle with little or no hesitation at idle, it transitions great. Normally I would think this is a lean low needle setting, but I have adjusted the low needle from 1.25 turns to over 3 turns with the only change being that the top end started to suffer around 2.5 turns richer on the low.

Could this be an air leak? I would think it would effect the whole throttle range and not just with a rapid acceleration from idle.

Could it be an ignition problem?

Could it be that the WT-664A carburetor is not suitable for this engine?

Any input would be great.

Thanks