I've been having some problems with a mousse can pipe that I built a while back. It's mounted on a Mac's header and is made from a 6oz. can with a 9/32" stinger about 3" long. I built this pipe for an Avistar with an OS 40LA. It did wonders for that humble little engine, increasing rpm by 2200 rpm and giving it improve transition and all around power.

When I put the can on a TT 46 Pro with the appropriate header and an APC 12x4 prop I started having serious problems with flame-outs at full throttle. What happens is that everything is fine (even on the ground) throughout the rpm range and power is a lot stronger everywhere until the engine is run WOT for a few seconds above 12,500 rpm. Then suddenly raw fuel comes spitting out the carb throat, the engine goes into a high rpm 4c/2c kinda burble and dies. During this spitting phase the carb cannot be leaned enough to change at all until the needle valve is completely closed. Then, of course, the engine dies and it won't restart until the needle valve is reset to it's original setting. Then it will run fine until the rpm get too high and the engine breaks into this irreversible decent into Hell.

At frist I thought the needle valve wasn't working right or maybe the engine had an air leak around the carb. After checking these things and calling the TT engine guy back East I finally decided the engine was a lemon and planned to send it back for repairs. However, after I put the stock muffler back on the engine ran fine with no problems whatsoever. I even put the pipe on an OS46FX and although it spit back a little less it did eventually do the same exact thing as the TT.

I'm thinking the pipe is putting to much pressure in the tank and fuel is being forced past the needle valve somehow but I'm not sure. The header, by the way, is 1/2" longer than the recommended length for a Mac's tuned pipe. I know the stock muffler will cure this but I really want the light weight power of the "canned" 46 for a fun fly Edge I have.

I've thought about a bigger I.D. stinger (or maybe two stingers!) or even a Cline regulator but before I go chasing after those birds I like to read some other's thoughts.

After reading the thread about the Webra 120 w/pump going rich while in flight I thought maybe my problems might be similar or in some way related. I don't know. Anyway, I'm hoping someone might have an answer to my problem.

Thanks,
Big Mike