1988 dt85 popping sound while running

[so]

Finally got her up and running, starts up every time if i open the throttle slightly but seems to be some popping sound? kind of like a fire cracker. Video is here

. you can hear it every now and then (i.e, at 0:27 and 0:30 mark) particularly towards the end. is that a knock?

For context; this is a continuation of my other post, https://forums.iboats.com/threads/low-compression-2-cylinder-1988-suzuki-dt85.763393.
Cylinder has low compression (40 psi), planning to do a powerhead swap.

 

[lakensea]

So is this the "new" powerhead, or the original one?

 

[so]

So is this the "new" powerhead, or the original one?

original. i wanted to make sure it can fire up before buying one. everything is original except the carb gaskets, fuel hoses and plugs.

 

[Faztbullet]

Hard to tell as not backpressure on engine...exhaust pop could be backfire in exhaust tube.

 

[QBhoy]

Just sounds to me like an engine running dry and not running on all its cylinders or with a compromised compression and/or ignition system.