wrong spark plug wire configuration. Check to see if two are backwards.
Out of time, or spark plug wires installed on wrong plug.
A backfire is caused by many different things. Using the wrong grade fuel will cause a backfire, as the engine's compression ratio is usually too high and will detonate the Air/Fuel mixture, causing a backfire. It can also be caused by advanced or retarded timing. Advanced timing will cause a backfire through the intake, as the spark occurs too early and ignites the Air/Fuel mixture before the intake valve is closed. Retarded timing causes a backfire through the exhaust as the spark occurs after the exhaust valve has opened. Your problem seems to be advanced timing. A backfire is caused by many different things. Using the wrong grade fuel will cause a backfire, as the engine's compression ratio is usually too high and will detonate the Air/Fuel mixture, causing a backfire. It can also be caused by advanced or retarded timing. Advanced timing will cause a backfire through the intake, as the spark occurs too early and ignites the Air/Fuel mixture before the intake valve is closed. Retarded timing causes a backfire through the exhaust as the spark occurs after the exhaust valve has opened. Your problem seems to be advanced timing.
The wrong spark plug wire(s) can cause engine problems including not running but won't drain the battery.
Its either too much fuel coming from the carbeuator and causing it to backfire or it could be spark plugs wired wrong. try to be more specific on where backfire is coming from. either out of the carbeuator or the tailpipes.
It could be the timing is not set correctly. Possibly one or more of the spark plug wires have been put on the wrong plug.
The engine , if it runs at all , will , of course , have misfires and may have a 'backfire' .
No There are many types of spark plug. They differ in size, heat range and amount of electrodes fitted. To avoid damage to an engine always use the recommended spark plug for that engine. The wrong plug will cause massive engine damage at times.
If your engine backfires when trying to start and the valve timing is correct, then it could be electronic ignition unit or the pick up that causes the spark to occur with wrong timing.
No, not unless your connect the plug wires wrong or one of the new spark plugs was bad.
it means there is something wrong with the spark plugs cause they provide the energy for the engine
Not definite, but possibly wrong timing when reinstalling cams and chain and heads, etc. other option is wrong spark plug wiring. spark plug wires on the wrong plug!