engine will not even turn on

[Jim860]

the engine will not even start up is it the spark plug? its brand new

 

[MotorBicycleRacing]

It used to start. What happened?

im running a stock exhaust on my 66cc bike engine and looking for more power like any one and i heard that removing the cap with add power. ia this bad for the engine and does it actually add any power. also any cheap mods that you know of that will add power.