just bought one yesterday for my son who is about 50 pounds also and having the same issues

 

One thing to check before spending money on gearing is the rev limiter. If you have that little screw turned to far in they can get the extra power needed to climb hills.

 

the engine seems to rev fine even if I back the throttle screw all the way out the atv wont pull. My garage concrete apron is about a 2-3 inch drop off into the gravel and unless you have a run at it will not drive up it acts like your sitting there slipping the clutch. I talked to the shop where I purchased it and turns out he is not a dealer and is a middle man on these and he said that's what you get with a Chinese bike feeling like I just threw my money out the window I knew I should have bought a name brand.

 

My Joyner buggy had the same issue. Threw lots of new parts to it. Mine was a bad rectifier (voltage regulator) and was not jetted correctly (too lean).

What is your location elevation?

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