ORIGINAL: Sport_Pilot
I think the original carb is oversized. Won't run well unless the muffler is restrictive, or use a pump or regulator. Otherwise the carb is excellent.
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Yep. I had the 1.08 Redhead of many moons ago.
I removed one tube from my Pitts muffler (can't remember the brand) and covered over the hole with aluminum roof flashing held on by six sheet metal screws and silicone glue. That took care of the muffler pressure problem entirely. Sweet running engine on 5% nitro fuel. More than that and it overheated and deadsticked continually unless an extra head gasket was used.
I had no problems with the stock carb after modifying my muffler. I wish I had kept that engine now. One flip starts were the norm.