I,ve got a Brison 5.8 single engine that is giving me fits, to say the least. I have been around the block and back with this engine with no end in site. I get it to start fine and runs at idle good. Has real good transition to full rpm, but when I get it in the air it starts to run rich at around the mid throttle position and will quit the second you pull it to idle. I have tried two dozen mixture settings already and have even closed off the regulator port with some bass tubing and ran the regulator back into the fuse with some fuel line. This engine runs great at full throttle and has lots of power but anything below half and it's just crap!!
I am out of options.. I have 8 other gas engines that run great and were easy to tune, this just blows my mind. Please help if you have any info.

Thanks

There have been a few cases where the engine will start and run fine, but after several minutes it goes crappy, sounds way rich, won't respond to needle adjustments, and will in general drive you nuts because you will try everything, rebuild the carb, change the fuel system, new this and new that. The cure is to get a new ignition, because the old one apparently has some component that goes ratty when it gets hot.

Try the ignition from one of your other engines and see if this fixes it. If not, well, you haven't lost anything but time and you have eliminated one possibility.

Any Brison guys out there that can help?