Are you sure you have the right plug?! If the plug is too long the piston will hit it. It will likely close the gap on the plug if this is happening! If you hear or fell a definite "clunk" or stop this is likely what's happening. Find the exact plug you are to use and inly use that numbered plug. Just because it fits, doesn't mean it will work! You can damage the piston (therefore the whole engine) if you use the wrong one. If it is electric start (you didn't specify), are you sure the battery is strong enough? Turn it by hand first tho as it may be the problem mentioned above! With the plug in there is compression and it takes more power to turn the engine.
Answers & Comments
Are you sure you have the right plug?! If the plug is too long the piston will hit it. It will likely close the gap on the plug if this is happening! If you hear or fell a definite "clunk" or stop this is likely what's happening. Find the exact plug you are to use and inly use that numbered plug. Just because it fits, doesn't mean it will work! You can damage the piston (therefore the whole engine) if you use the wrong one.
If it is electric start (you didn't specify), are you sure the battery is strong enough? Turn it by hand first tho as it may be the problem mentioned above! With the plug in there is compression and it takes more power to turn the engine.