Fix the timing.
Fix the carburetion.
The throttle blades have to close, to leave a little square hole of transfer port under the throttle blades. Or very near to square. And no vacuum leaks, and no exhaust flange leaks, none. If the exhaust pulls fresh air into it, a rich mixture in there will re-ignite and burn, making a lot of heat and often,noise. Ie pops.
