Why a moped doesn't run:
- No feul
- No spark
- No compression
- Wrong ignitiontiming
- Wrong feul/air mixture
- Too much oil in the feul
What to do:
Turn out the sparkplug and look at it. If it's black and muddy there's too much oil in the mixture. If it's just Blackened there's too much feul in the mixture. If it's white there's too little feul in the mixture. Clean the sparkplug or replace it for a new one of the same type. Refit the plug and adjust the mixture if needed. The sparkplug should be colored coffeebrownish. Wrong mixtures are caused by fauled up or poorly calibrated carburettors. Now set the bike in gear and push it forward, if there's no or little resistance to movement there's no or little compression. If there was compression you would have to push quite hard to get the krankshaft to turn over, the rear wheel will probably block if there is compression. If there's no compression you'll need to fit new pistonsprings or even bore up the cylinder and fit an oversize piston. Some mopeds also have a valve in the cylinderhead to make it possible to get the krankshaft to turn over in order to start the engine, this valve could be leeking. If this is all well it's the ignition. Turn out the sparkplug again and hold it against the cylinderhead with the cable attached to the plug while you crank the engine, if there's no spark you'll need to run by the entire ignition system to locate and fix the problem. If it does spark the igintion timing is off by a leage. Reset the contactbreakergap or replace the contactbreakers if they're worn.
Other less likely problemcauses could be a leaking minifold, a clogged exhausts, a leaking cylinderhead or faulty/rotten wiring.