Workhorse new engine no power

[skswave]

To all I am running out of ideas

I have an 800g workhorse. It has a rebuilt motor with good compression and runs great on the flat. The moment you head up a moderate hill it it has no power. The clutches appear to be working properly and as the engine slows down the belt is properly in it's low speed position. The motor just does not seem to be making the power. I also have a 1200G workhorse which gives me a referance baseline.
The throttle is wide open on the carb.
Tried removing the muffler no change
Replaced fuel filter no change
Coil is new
Cleaned the carb no change.

My next step is to pull the carb on my 1200 and put it on the 800 and see what happens.

The motor just never makes the RPMs

Thanks for any thoughts

steven

[ruredy]

assuming that the engine is right...sounds like a belt, clutch issue to me.
If the belt/driven clutch aren't right, it'll not be geared right, making it impossible for the engine's limited horsepower to over come