ORIGINAL: mando

Hey Fellas, seems like I've been chasing my tail this afternoon, and maybe you guys can steer me in the right direction.
I've been running a new DL50 since last summer at 30:1 with a 22B Vess with great results, smooth transition on throttle up and a touch of low end burble that was hardly noticable. This spring, two weekends ago, I switched to Belray at 50:1 with even better results for engine power and the burble went away totally. Remember I've had nothing but great luck with this motor. This weekend I switched the prop to a Vess 23A, with no carb adjustment. About 4 mins into the first flight it spit and sputtered a little and died, deadsticked and landed safely.
Maybe a little lean? RPM checked at 7500-7600, tuned the high needle down to 7200 RPM and fiddled with the low end for smooth transition and burbble. Each time before adjusments, I shut it off, adjusted, and it would restart with one or two flips, running great I shut it off to cool and get a drink. When I came back to it 10 mins later it didn't want to start and would only run with the choke on. So I opened the low end until it would run, 1.5 turns out, would not run very well and I couldn't get any RPM out of it.
I don't think I should be chasing the needles at this point, What else should I be looking at?

Thanks much..................