Our good friends at Motorbicycling.com has some great tips for your clutch installation. If your back wheel is not spinning and your clutch is having issues, try these tips.
How to adjust cable:
1. Loosen the lock screw in the brass cable end until the cable can slide through it. Do not remove the brass cable end from the cable.
2. While keeping the brass cable end in the cable hole on the tip of the clutch release arm , grab a hold of the end of the cable with pliers and pull the cable through the brass cable end until the cable is tight.
3. Swing the release arm (with the brass cable end still in the tip of it) inwards towards the carburetor until it stops swinging. Do not forget to keep pulling the cable through the brass cable end as you are doing this.
4. While holding the cable relatively tight and keeping the brass cable end in hole at the tip of the release arm, and the release arm rotated fully towards the carburetor, tighten the lock screw in the brass end.
The cable strand between the cable housing stop thingie on the top of the engine case and the release arm should almost be in a straight line now.
You should barely be able to wiggle it. It should not be as tight as a piano wire though.
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 in with the lock button or some tape or a piece of wire, zip-ty, ect.
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.
Basic Cable Design
A cable has two parts.
There is the actual inner cable with connectors on each end in this case to the clutch handle and the clutch arm, and an outer cover.
The outer cover is not for decoration!
It is an actual crucial part of a cables mechanical ability to transfer force from one place to another in a flexible form!
When you 'tighten' a cable with in-line adjusters you are not tightening the inner cable from point A to point B, you are adjusting the difference between the inner and outer cable parts.
For example the kit locking clutch lever has an adjusting screw and locking nut.
The adjusting part is the cone shaped part the cable cover fits in, the locking nut is the bigger ring.
Make sure this is screwed in as far it will go before adjust the brass lock connector on the clutch arm side.
If your clutch won't disengage after some inner cable stretch and outer cable shrinkage you can tighten it up by twisting the cone out and snugging the locking ring up against it to compensate.
There is also one that is mounted on the motor itself under the Carb but it much harder to get to.
Once the cable is adjusted
It is very common for the grease in the bearing between the clutch plate and outer gear to the motor to dry on the literally slow boat from China trip to the US and warehousing, and pulling the lever does not seem to engage the clutch to disengage the motor from the drive sprocket.
This is usually not the case at all and the clutch pressure plate does indeed move away from the friction pads, the dried grease just has the shaft locked to the gear.
Pop off the right cover.
Pull your clutch lever, that big sliver plate should move out towards you.
If it doesn't go back to cable adjusting until it does.
Now pay close attention to the locking screw and flower nuts position, mark them if need be for reference, then pull the flower nut lock screw and unscrew the flower nut.
To make this easy lock your clutch lever in the engaged position and you can twist it off with your fingers if you push the plate down with your hand while doing it.
The same goes for putting it back on.
Pull out the pressure spring and you find the business end of what makes a clutch work.
Understanding the Clutch
Using that pic and my terms as reference, the little gear is the actual motor crankshaft output.
The large gear is a plate that holds all of those little friction pads, and it 'floats' on a bearing that divides at the 'Bearing Seam'. That is usually what dries out and locks the motor to the drive train and needs breaking free.
The silver pressure plate you removed earlier rides on the those 3 'Clutch Plate Float Guides' so it can be pushed away from making contact with the pads, but still staying connected to the output shaft, thus disengaging the motor from the drive side, but making contact when you release the clutch so the plate makes contact with the pads to the big outer gear.
To Free Up That Bearing...
A long flat head screwdriver works dandy for me.
All you need to do is use two the Floating Guide posts for leverage and without the motor gear moving.
CRUCIAL IMPORTANT NOTE!!! Do NOT use that center Disengaer Shaft as a leverage point!
Give the screwdriver a hard push down and it should break free.
If the motor gear moves you need to stop that from happening, the point is to break the bearing free.
The gears need to not move, just the inner part to the drive sprocket to break it free.
NOTE: if your drive train is hooked up to the wheel lift it so it will turn, that inner shaft goes directly to it.
The common practice to keep the motor locked is to put a wooden dowel of some other thing that wont scar the cylinder wall but block the piston moving down the cylinder head from the plug hole, but as I look at this it seems to me you could just wedge a piece of plastic or something in where the two gears meet so they couldn't turn.
It's not like you are breaking a piece of metal, it is just freeing up dried grease in a bearing.
Once you have it free
Clean out all the gunk between the pads and put a liberal amount of new grease (not oil) on that Bearing Seam and the gears, and I put a light coat on the pad tops too.
Many say 'run it dry' but I find a little grease makes the transition from the drive being disengaged to engaged smoother with a little grease on those pad tops.
Adjusting the Flower Nut
Put the spring and plate back on and put the flower nut about where it was.
Lock your clutch in and roll the bike around, does it roll free?
If not, back the flower nut off 1/4 turn until it does.
Once it rolls free, let the clutch lock out and try.
Does it engage to the motor?
If so put your set screw back in (lockTight it of you have have it) and button it up, you are done.
Remember, if you start getting clutch loss, you have two places to adjust for it, the clutch lever is just the easiest.