If you bought a bike without parts or tech support, I just hope this helps.
(But, don't call me if it doesn't!)
This guide applies to most all 2 stroke engines and generally applies to 4 strokes as well. Feel free to print this or link to it leaving the copyrights intact.
If you want wiring diagrams or repair procedures, order a manual from
Parts Department Online!
If carburetor has primer or choke, activate same. If fuel does not flow: remove fuel line from carburetor, open fuel valve and watch for fuel flow. If fuel flows, proceed to STEP 3. If fuel still does not flow: check fuel level in tank, if OK, clean tank and fuel filters. Attempt to start moped, if moped does not start, proceed to STEP 3.
Check for adequate spark.
Remove spark plug from cylinder head, ground outer shell to engine and crank engine. Observe the spark, a crisp blue color is normal, orange color denotes ignition malfunction. If a strong blue spark is evident, proceed to STEP 4. If weak or no spark: replace spark plug with a known good spark plug and retest. Still weak or no spark: unscrew plug protector from the high tension wire and hold wire 1/2 inch from engine and crank engine. If spark occurs, replace spark plug protector and proceed to STEP 4. If no spark, check the ignition points to make sure they are opening and closing. If they are but points are blue or burned, replace points and condensor. If spark then occurs, attempt to start engine. If spark does not occur: check magneto by cranking engine with headlamp on, if headlamp lights, magneto is functional. If not, replace magneto and attempt to start. If spark still does not occur, replace ignition coil and attempt to start.
Check and adjust starter clutch adjustment. Check engine compression, 2 cycle engines need at least 90 Lbs per sq in of compression to run (4 strokes may run at 75 or less). If not so, you need to check for carbon buildup in port or exhaust or you need rings and/or piston service.
Attempt to start engine. If it doesn't start, check spark plug for the following conditions: if wet, recheck fuel quality for staleness or contamination. Possible causes are: excess oil mixture, clogged air filter, or main jet too big or loose in carburetor. If plug is dry: clogged main jet, stuck needle or float, or clogged filter in carburetor.
Having corrected any deficiencies in these areas the bike should now run! Assuming of course, that you the minimum of 90 lbs (or less for 4 strokes) of compression to run.
Check for dragging brakes, tight chain, under inflated tires, defective spark plug, clogged air filter, clogged exhaust or port, choke not returning to fully open, low float level, incorrect or drilled out main jet, or incorrect ignition timing.
Wrong gas/oil mixture or defective crankcase seals.
Check for loose carburetor or manifold, defective crankcase seals, or incorrect carburetor adjustments. Could also be defective throttle cable or cable adjustment.
BIKE STORAGE PROCEDURE
Storing for winter or any other prolonged periods?
1. Drain the fuel system.
2. Start engine and let it run out the rest of the fuel in the carburetor.
3. Remove sparkplug (s) and squirt oil into the cylinder (s) and replace sparkplug (s). Crank over just once or twice.
4. Lower tire pressures and raise off the tires if possible.
5. When ready to use again, crank over with oil still in the cylinder (s) before attempting to start.
6. Refill fuel tank and tires.