A had take my bike to a motorcycle mechanic. It was backfiring and smelled gas all the time. I that we need a tune up. Constantly stalled with me even in intersections with a passenger beyond me. All the mechanic  would had to do is adjust the idol screw say half turn to the left . Rich  the mixture. Lean mixture  bike pops as you ride (and stall because is to lean), rich mixture pops when you turn off the ignition (or stall on the road because the chamber floods). When you adjusting the idol screw you have to do that a 1/16 per adjustments.  My carburetor is 2 turn to the left right now. The mechanic  take the lid off the diaphragm . To take a look and see if everything is  alright no crack in it.. When he was placing the lid back on top he  didn't set  the diaphragm edges back to the groove correctly. It was loosing pressure all the time. And it was impossible to tune it right.  The motorcycle worked the popping stopped , but it was still stalling on me. Idling going up and down . Daily.  The choke stopped working. Gas was pumping out on to the engine from one of the air intake. If i puled the choke out the bike died instantly. With choke on would not start at all. After the mechanic worked on it . For two hundred and sixty dollar  A joke right? My mechanic said the choke : you don't need it . You leave in Florida. Choke is only for cold mornings. So i said no way and started  looking for answers like everyone here..finally i that it's could be the petcock. Read the instruction how to remove the seat and the tank. Yes i wrenched Friday afternoon. Changed (rebuild) the petcock . After that i take off the housing  off the carburetor diaphragm  . I saw it at one part the diaphragm was not sitting in the groove. Yes i saw it but didn't think anything of it. It was just inward a little bit. A 16th off the groove. Remember after the mechanic serviced the bike. So of course i pulled the whole thing out of the groove and just to check on it . But when i was put in it back together some part of the edge , this time even longer section wasn't sitting in the groove correctly . I that when the lid goes back on  it will automatically forces the edges back to the groove. Didn't think anything major of it. I assumed. Changed all the hoses .Make sure there will be vacuum  leaks. Bike was back all together. Started. Instantly. But the throttle had no response at all. It was flat .  Idol worked. But i lost all power and my top speed was 20 in second gear. Choke didn't respond it at all but at least didn't stalled the bike. Saturday Morning. Wrenching again. I strait went for the diaphragm. Opened it. This time (after my first attempt) it was a way longer separation from the groove so no wonder i lost all power. Boy..how wrong i was not to pay attention for the diaphragm , the stinking groove..assuming..what is  have to be perfectly airtight together creating a perfectly airtight fit . So double check the groove and diaphragm connection , before you put the lid back an to top. Warn your mechanic..or for the do it yourself. I had to give it try it several times before finally it didn't popped out of the grove. Takes lot's of patient . Bike back together. Starting. First try like a charm. Afraid to pule on the throttle . I don't want an other disappointment . I tried the choke. And all of a sudden what a sound..engine idling faster. The choke works again .What about that. Now i tried the throttle..What a respond. Hum ...hum..i feel the power again .  So i reset the idol screw once more. . The bike barely makes noise in idling .  You would think it will stop. I set it to fairly  low. Lets go for the road. I am blown away. I have a way more power then ever. Feels like it like 20 percent more horsepower. It pules a lot faster then ever. Unreal what a change a diaphragm leak can create. No Pops no Stops...FINAL WORDS ...don't trust your mechanic. He may never seen a carburetor like yours . He screwed up my choke and DIDN'T put the diaphragm back  in correctly . And he is a Pro..should have known it better. He made the same mistake as i did at my first try. So the bike back in to perfect shape better then ever condition. More power better response. FASTER . I hope i was able to help a lot's of people with stalling or popping problems....i tried to look for answers on the net some confusing..some better ones..and it was very difficult in many ways. I hope my little articles helps many of you...say thanks if it did and helped you  out....a backyard mechanic.....LT

Ya there's little things like that you have to watch for. Like the spring and o-ring when you change oil filter. Make sure filter is not in backwards.  Must be in correctly or it will not flow and/or leak. Same with timing inspection cap on the other side. And the gasket on the oil  drain plug. Or the o-ring gaskets on the valve covers. Gotta make sure they're all where they should be and tight. Carburators especially, are very touchy things. If they aren't assembled correctly, they're not gonna work right.