I just did my initial engine break in on my porch. I noticed allot of bubbles in the fuel line. The tank is wrapped in 1/4" foam all the way around. Is this normal. The engine was running a little erratic but I'm not sure if it was due to the bubbles or the cycling between 2 stroke and 4 stroke as called for in the break in instructions. It is a great planes 10oz tank. The engine is an os 46fx. The tank was full and remained level. This has me baffled. Is there too much forced air induction from the exhaust? This is the only thing that I can think of.