Is popping or backfire normal?

the carbs might need to be reajusted or the timeing is off if you have it rejetted it should clear up

It could need carb adjust.
If you or someone else adjusted the air/fuel screw on it.
Also altitude change can affect it to a degree.
Also if your ignition timining (when the spark plug sparks) is off.

If it is making the "backfire" sound out the exhaust then it's actually "afterfire"
"Backfire is when it actually makes that noise going out the intake side.
If it does that going out your intake side you probably have a mechanical problem (timing).

I would check spark plugs first then if that does not solve the problem. ( GAP AND SPARK) Then lean the carb out. If you recently moved from a lower or higher altitude place then you will need to have the carbs set right for the place that you are going to be riding. The backfiring is an ignition that happens after the combustion in the motor. The gap in the spark plug could be too small or not existent causing this or its the mixture of fuel/air. This would be my first step for solving this problem. After you try this let me know how it runs...

It sounds like a lean backfire. You may need to also clean and adjust the air/fuel mixture screw. It is on the bottom of the carb and is probably covered by a brass plug that you will need to carefully drill out. before you remove it turn it all the way in till it is slightly snug and count the turns so you can put it back to the settings. be careful not to tighten it to tight as you can damage the needle. There is also a o-ring (very small) and a washer also very small in there with the needle and spring. After you clean it and reset it, if it still backfires on decel then turn the screw (it can be done without removing the carbs with a 90 degree screw driver that can be bought at a tool supply) in or out till the backfire stops. be careful to count the turns out as you dont want to go more than 3.5 turns out that would be to far and the screw could fall out. I hope this helps you. Thanks and have a great day.

The most common reason for backfiring is lack of back pressure from changing the exhaust. To compensate for the flat spot you get you put in a jet kit. This leaves the possibility of more unburned gas getting into the exhaust. Honda uses Kei Hin carbs with a fuel shut off diaphragm to help limit this condition (backfiring) by turning off the fuel to the carbs during deceleration. Even stock exhaust can pop or backfire. Typically it is caused by air getting into the exhaust either past the copper o-ring gaskets in the head or leaking muffler connections from the head pipes to the mufflers. Try replacing all the exhaust gaskets and you should minimize this condition.

did you change the exhaust and air filter? if not, you should. bike is running rich. lean it out a little and you'll be alright.

I replaced spark plugs, filters, tightened boots, etc. Nothing worked. Then I dumped Sea Foam in the gas tank. 50 miles later...no more backfiring. I used 1 ounce per gallon. Get it at any auto parts store.

I still have the popping on deceleration after cleaning the carb.