89 engine running poorly

[metallica21156]

I picked up a 89 this weekend. I got it running yesterday. When driving it around it just doesn't seem to have much power. Running up the road in front of my house at a slight incline it stuggles. When i got to the top which was probably 5 mins run time the muffler was smoking like crazy burning off oil. Seems to run good at low speed. When running up the incline i kept a eye on the carb and it stayed at wot the entire time. Current mix is 50:1. I know its not the 128 but could this be the reason for lack in power? I pulled the muffler and ran a heat gun both ways. Outlet side did produce some smoke. Blowing through it doesn't seem too bad. Running it without it on it seemed to run better but i wasnt going to try to run it up the road with how load. Compression is 120 and engine starts easy. Spark plug has brown on porcelain.

[Leon willis]

Did you try a card rebuild I had the same problem with my 1983 TXT 3 wheeler