My Motorized Bike Clutch is Slipping!

Here's a few ideas on how to improve your MB's slipping clutch.

Kit-supplied gear puller in place

Cleaning: A clutch will slip if the pads are oily, greasy from carburetor overflow. Cleaning off the pads and clutch plate will help it perform better. EZ job.

Adjusting:
Adjust the flower nut tighter to within 1/8th" of the pad surface.
Ensure the small fastening screw is back in place.
The clutch lever & cable should be adjusted so a reasonable effort allows
the round clutch cover to separate / lift up 1/8". Test it.

Flower Nut & Clutch Plate

Clutch Pads:
The pads (number 8 on diagram) will eventually wear down past the point of proper contact = slipping especially on hills. Replacement clutch pads are as little as $5 on ebay.
I use the red high-temperature pads.

WORN DOWN PADS

NEW RED HI-TEMP PADS

Clutch Spring tension:
Adjust the main spring tension (on the bike) by removing the cable securing post under the carburetor.
Insert a thin screwdriver in the hole between the collar slots then push the bike backwards.
Keep tension on it - about 1 to 1.5 turns is enough to increase clutch spring tension.
The clutch lever squeeze may be a tad firmer as a result.




















Clutch Main Shaft & Key-way:
Left side, under the chain drive sprocket cover.
Here's a real difficult situation. You've done all the above and still your clutch doesn't work
- at all. There's no engagement to allow bump starting or riding.
Don't panic...
Most likely the rear sprocket / main shaft slot and key-way are buggered, galled and the woodruff key is either broken or slammed away from its slot.
Examine the main shaft carefully. The key way must be intact, and not burred out.
I replace both worn parts; the rear 10T sprocket & small key.
Ensure the sprocket securing nut & star washer are tight.
Check it every month or so.

under the Carburetor - adjustment slot just visible

Damaged Main Shaft and Key-way - beyond repair

If the main shaft is grooved / galled then it must be replaced - approx. $20 or less. 
That's the entire shaft, clutch spring with collars. 

Drive Sprocket Side - Main Shaft

Check the bucking bar - is it worn, too short? It should be 1.045" long.
The clutch ball limits are .3125" with minimal wear visible.
Depending on your mileage, grease these parts every other month or more.

The direct drive chain needs some slack. The "droop" needs to be 1" to 1.5"
Try to get away from using a chain tensioner. Adjust your bike's chain
length by using half-links. Keep the 'gunk'; greasy sand and grit cleaned off.
Oil the chain weekly or more if it looks dry.