Thanks for the service manual link Nosedragger. As I get more into the tuning piece of this, I'll consult it. Deliberately, I haven't even touched the needles, yet I've noted that the start & run symptoms have grown inconsistent. Never would hand start, but would start with the starter. Sometimes would quit at WOT, sometimes on decel. Sometimes it would start quite wet (carb), other times it would fire not so wet.

This evening, while trying to start it with the electric starter, on a sudden whim, I got brave and reached over the spinning (not running, just spinning with the starter) prop and pushed DOWN on the spark plug adaptor with the rubber end of my chicken stick. The engine CAUGHT and ran immediately, then died again when I let up with the chicken stick. OK this RCEXL P.O.S. is defective on two counts. This intermittency, and the previously mentioned difficulty in soldering. Anyway, I stuffed a second spring inside the shroud and now I can hand start it. Did it twice. I feel rewarded for resisting the urge to start messing with the needles too soon. More running and investigating tomorrow night.

I should mention (since I'm slamming RCEXL) that I emailed my photos from this thread my fix to the soldering issue of the RCEXL 1/4-32 plug shroud (the split brass sleeves) to Paragon, and that guy emailed me that he's forwarded my email to RCEXL to see if they could find a way to reproduce this fix. This is after he told me I'm the first one to have this problem. Really, RCEXL doesn't need to do the brass sleeve. I just did that because I don't have a plating shop in my basement. All RCEXL has to do is tin plate the two carbon steel shroud halves and it would solder just fine. Now, I discover they need to have a longer spring to overcome this intermittency too.

I'm also wondering how the thin con rod and needle bearing are holding up. Soon, It'll be time to pull the backplate for an inspection. I also replaced the super thin pulse line tubing with a larger diameter tube. That didn't help at all (I did this before I discovered the plug making & braking). I think it was starting (sometimes) with the electric starter because that caused the whole motor to shake and vibrate more than hand starting, probably causing the shroud to make contact sometimes. I'm sure the spark was jumping the gap sometime too. But hand starting was too gentle to make any of that happen.