Working on neighbor LT80. cleaned carb , air filter bad ordered so is not on yet. Start and it smokes no power, removed exhaust and I ran for couple seconds runs good. I cleaned exhaust ,reinstalled ran good for a minute and idles down and no power. compression after running 100 psi . turn gas off and as it runs out of gas and it starts to run good till out of gas . got good spark while it runs bad or good. is there a good replacement carb? or are kits any good? other ideas like low compression,Thanks

 

OEM carbs are best but they can go bad if in dusty conditions. If it's flooding (which I suspect) you may want to get a kit (OPT liked Shindy kits) and swap out the float needle and seat.
The comp (at 100) is ok.
What did you do to the exhaust to clean it?