Xsport Pit Bike

My Xsporter will start with the choke on but when you rev it makes a crackling noise and pops a lot. Ive already checkedand cleaned the carburetor, but I think there may be something to do with the wiring of the CDI box. Could this be the problem or could it be something else. Thank you!

You can check the plug and check for air leaks around the carb. Check the coil / CDI unit by testing a permanent replacement set.Most built in adjustment of the advance / delay, but the types pitbike and some 2 strokes do not need it, I think.A Overall Kill / unit cdi / coil / wiring Genny is available from Pit Bike Parts for about 25 pounds.
If the bike has been beaten, you should check the valve timing and valve clearance. An oil change can help. Finally try a compression test to check the rings / piston.Many these bikes suffer from a complete lack of maintenance and found many were running out of oil.
If the valve / cam chain has'nt been adjusted to the right, then he may have jumped a tooth, check by examining the timing marks.