It sounds like your clutch flower nut is adjusted too loose and your clutch is slipping too.
Adjusting the clutch:
1. Adjust clutch cable so there is only a little bit of slack in the inner wire when the hand lever is released all the way out.
2. Remove gear case cover from right side of engine.
3. Remove lock screw from clutch outer plate. It's the little screw that fits into the notches on the edge of the center nut (called a flower nut).
4. Squeeze in clutch hand lever until it touches the hand grip. Hold it there with some tape or a piece of wire.
5. While pushing in on the outer clutch plate with one hand, tighten the flower nut until snug, just using your fingertips. Do not use pliers, ect.
6. Unscrew flower nut 1/2 to 1 turn out, aligning a notch on the flower nut with the hole in the outer clutch plate that the lock screw goes into.
7. Install lock screw but don't tighten it just yet.
8. Remove tape or wire from hand lever and let it release all the way out.
9. Tighten lock screw for flower nut.
10. Adjust clutch cable if necessary to give just a little free play to the inner cable when the hand lever is all the way out. You should be able to wiggle the clutch release arm a little.
11. Install gear case cover and test ride. Every clutch is a little different.
You may have to fine tune the adjustment of the flower nut by a few notches.