Sport Pilot is right, the carb is too large. It will work if you run it with the factory muffler, which was an exact clone of the OS 61 FSR muffler (which I had several of, to compare). So, they opened up the carb to get more rpm, then when it wouldn't suck fuel, they used an undersize restrictive muffler on it to increase tank pressure. I could not richen the engine enough for safe flight on my first one, with a Slimline muffler (fairly open) and the stock carb. I put it on the bench, and it would run ok with the factory muffler. It would also run ok with the Pitts style, as long as I used the OS 7D carb, and I only lost 100 rpm in the process. So both of my ASPs use the OS carbs and run very well with Pitts style mufflers.

An interesting side note however, I tried the ASP carb on one of my Webra 120 engines, which happened to be pumped (Perry P-30), and the carb worked as well if not better than the Webra carb.

So.....live and learn, I guess.

Clair