I got 1500 miles only :-( on my CH80 "no name" I purchased on eBay. Learned a LOT about engine mounts, air leaks (carburator side), tires, chains, grease (on everything), clothes to wear, clothes to not wear, bicycle tire bearings, tool kit (10 mm open end, crescent wrench, screwdriver with bit assortment, spare engine studs and bolts, spare plug, etc.), check all bolts prior to every ride of any duration, etc.
Lots of hills here, my upper bearings were trashed, happend on the flat at low speed JUST AFTER posing for pictures at a local gas station JUST AFTER mixing a tank of gas + oil in the tank.
I only ever learn by doing things wrong, sometimes a couple of times ! But thats OK.
I just got my new DAX CH80 up, that I bought at Fall prices (!) on eBay. 134 with shipping - fantastic. Roller bearings upper, but bushing lower, may be better on the bushing anyway. For this build ->
1. Fingernail polish a.k.a loctite on engine mounting bolts on engine side.
2. Double nuts on mounting bolts, 2nd one as a security feature.
3. Rubber mounts on the engine clamps (what works best is bike intertube split lengthwise about 6" long on both frame tubes).
4. Rubber mounts on gas tank, cdi mount.
5. Plumbers tape on fuel petcock threads into tank
6. Plumbers tape on top of carb where cable mounts (this can come loose and cause air leak).
7. I don't use any kill switch, had problems with the first one shorting out, couldn't start the engine and spent a lot of time figuring out why. I just dump the clutch at idle - don't know if this is good.
8. I put washers + lockwashers on some bolts that don't have them, e.g. where chain guard attaches to engine.
9. Grease front and rear bike wheels complete using a grease NEEDLE and grease gun.
10. Dab of grease on drive gears under clutch plate cover. Lithium grease doesn't appear to spread real well here.
11. Religious break in period.
After break in, I will put cardboard (or coat with silicone) on underside of clutch plate cover, as I learned on the forum, as this cuts down on gear noise. A lot of noise indicates need for grease, I had to grease the old one frequently.
My 2 cents
cb