Where's it jamming? if it's jaming around the front sprocket then it sounds like KC has it nailed.If that's the case.I would just add that you should install the retaining clip so that the opening of the clip is trailing in the back during operation.
If not your chain could be jamming on the casting boss for the bottom screw of the cover.
If your chain is loose enough.
I mold metal putty on that little "shelf" on the casting boss and let it harden.In a Kinda 1/4 moon shape.Make sure you mold the putty so that the cover can be re-installed properly.
This creates a nice transion for the chain to follow and not catch.Also when you have that cover off check for chain wear marks on the cover expecially on the front "wall" of the cover if there is I notch the wall out a little wider than the chain for clearance,or you can file or dremil it for clearance.
While your at it pull out the clutch actuator rod.It's that 8mm round rod sticking out of your motor,Be carefull there's a ball bearing in there.
If the bearing stays in good.take a little dollop of grease and smear it in there.About the size of a small marble.
Then clean off your actuator rod and check it for wear marks along the sides.
I've seen them with burrs from where the factory cut them on one end and lathe cut off nipples on the other end.make sure it's de-burred and file the nipple off."Don't round the ends"Just take off the sharp edges.
Then I smooth the rod up with sand paper and grease it and re-install it.With a dollop of grease on the actuator end.
A little PM while you have it apart might help down the road!Kip