Ok, I cannot seem to get this car tuned right, and the HSN seems to be very loose.

Symptoms are -
It does not seem to run really fast. I have a .27 engine, "Team Infinity" brand, that runs like crazy... and I thought it should compared to the .21. But I've been told the .21 Hyper should actually run as well or better than this brand of .27. It doesn't. Not even close.

Won't hold a tune.

Doesn't want to reliably start.

At times, it doesn't want to let you prime it. The air keeps pushing it back into the fuel, even though the fuel line is run well.

To get it to run good, the needles need to be much more lean than "manaul specifications"

I wish somone here could see it run in person, but based on what I've said here - is the carb bad? The engine looks good from what I can tell and seems to have good compression. How would I know for sure if it has good compression though? It seems pretty tight to me.

Any advice is welcome. Do I buy a new carb?

Or just sell this engine and pick up a new one. If I buy a new engine what should I get for the Hyper 7?

Thanks

PS - I bought it used, so I never saw the .21 run as new... so I don't have anything to judge it by as far as that goes.