To any that can help:

I have an older 3w60 engine (side carb) with only about 3 hours running time on it, 4.8volt system. The low range and high range are great as well as the transition, but right around the middle, I have a "burble" or "two-cycling" sound that is causing me fits. It is running at 50:1 with no bad habits or stalls.

What can I do to fix this? I am running a 22x12 prop for my Byron Corsair and it flies great, temperature fine, no other issues.

Thanks!

David