Popping back in through the carb?
Put it up on a stand, can you make it happen? Make a video and send us the link...
Its hard to diagnose "a popping sound" with nothing else to go by.
Raising sleds from the dead in north central MA.
'70 Ski-Doo Olympique 12/3 - The Yellow Bullet
'71 Arctic Cat Panther 303 - Wankle Panther
'78 Arctic Cat Pantera 5000 - Back from the dead!
'79 Polaris Cobra 340 - Back from the dead!
'95 Ski-Doo Grand Touring SE 670