my mini bike misfires, what to adjust?

[foreveryoung]

sorry I shouldn't say misfire, It detonates!!! when letting off the gas at full speed...
It performes good when it starts from a dead stop to a full speed but about a second after I have let off the throttle at full speed it makes a loud gunfire explosion sound that makes me think something needs to be adjusted, (what is it?) :001_unsure: it does it at least once every pass.

Is that normal???

 

[minidragbike]

It's running good, but if you really want that sound gone you can increase the size of your carburetor main jet. The facory jet's are pretty small in the stock carb. If you remove the air cleaner completly it will seriously run lean.

For a little extra power remove the air cleaner completly, and install a #90 main jet. This should give you about 1/2 HP, or 300 more RPM depending on gearing.