Re: bought a replacement engine and it wont start.
To check for ignition you must remove the spark plug from the engine. Reconnect the plug lead to the CDI and hold the plug firmly against the cylinder head cooling fins. Either suspend the rear wheel or push the bike forward at a good pace, clutch engaged and watch for a spark at the plug's electrodes (the end of the plug that would be inside the engine if it were screwed into the head). The wrench flats, or the area where you put the wrench or socket needs to be in contact with the engine cooling fins to complete the electrical circuit.
Keep in mind this fact: The engine needs three things to run. Fuel, Air and Ignition. You'll need to confirm all three then get back to us with what you find.
Fuel: Disconnect the fuel line from the carburetor, open the petcock on the tank and see if fuel is flowing.
Air: Remove the air filter and look into the throat of the carb. Operate the choke lever. Is the choke open? It should be.
Check these things and get back to us with what you find.
We'll get you going, we just need some information first.
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