I have both the .45 and .46NT Evolution engines and they are both great. Both also had small air leaks in the fuel tubing from the HS needle valve to the carb. I changed that right away. On my .46, I took the baffle out before I did anything else.

I've read and heard about problems with the settings done in China for the needle valve settings. A lot of people need to reset theirs to their own location. I took the collar off of my engines.

These engines are manufactured to be tight. I ran mine for a few minutes before flying. It had more power than my OS .46FX on the first full throttle takeoff, but it didn't really run smoothly for another 5-6 tanks of fuel. It now sips fuel almost as good as a my 4 strokes.

I disagree with the assertion that these engines weren't tested properly. They are some of the best 2 strokes out there. They are very forgiving if you don't have the needle valves set properly. They rarely, if ever, give you dead sticks. The crankcases don't seem to load up much. You just have a problem somewhere and it happens all the time.

How far back is your fuel tank? Is is lower than the engine? Can you run the engine and see if the vent line system is working properly? Is your vent line in the tank unclogged? Are you sure you have the needle valves really set properly? What prop are you using? What is your nitro content? What plug are you using? Maybe it's time to checx all of these things. And, maybe the HS needle valve needs back flushing.