What causes popping in one cylinder.

I have a 76 Kz50B. Got my bike running and everything is cleaned out of the carbs. Timing is dead on, and I'm pretty sure they are synced well. Was are the major causes of popping. I have just the headppes on, and theres a leak in the exhaust gasket of the same cylinder. Could that be it?

KZCool wrote: I have a 76 Kz50B. Got my bike running and everything is cleaned out of the carbs. Timing is dead on, and I'm pretty sure they are synced well. Was are the major causes of popping. I have just the headppes on, and theres a leak in the exhaust gasket of the same cylinder. Could that be it?

Yes, leaky exhaust gasket will make the popping sound louder. Popping on decel is caused by a lean condition in pilots or also vacuum leak, timing off. I recommend #50 pilots.

I've already increased the jets since I have a K&N filter, but I couldnt tell you what size. And its just at idle when its warmed up that it pops. It's not that I can hear the pop from the gasket leak, I just thought maybe its somehow messing with the air flow or mixture or something. I'll get a new gasket anyway.

Do you plan to install an exhaust system? Running with just header pipes and no collector or can is going to make tuning difficult not to mention reduce the engine's power because of the absence of Bernoulli effect (scavenging) and the gross reduction of back pressure. Ed

As mentioned, a single carb popping is a LEAN condition due to more air then gas whether it's from leaky manifold, miss adjusted pilot air screw, screwed up carb circuits etc...

"I'm pretty sure they are synced well"... :huh:

If you took those carbs apart to clean, chances are they are not sync'd...
Ah hell with it, I'm Pretty sure they wont be... :pinch:

Wild guess here, when was the last time you sync'd them...?

Before going crazy on the carbs... Confirm your sync, you might be surprised how far off they can and will be otherwise you'll be chasing this all over the place.... Then go after your proper jetting... It's a trial and error scenario to get dialed in especially w/out the right tools (Vacuum Gauges / Morgan/ Color Tune etc...)...

KZCool wrote: I've already increased the jets since I have a K&N filter, but I couldnt tell you what size. And its just at idle when its warmed up that it pops. It's not that I can hear the pop from the gasket leak, I just thought maybe its somehow messing with the air flow or mixture or something. I'll get a new gasket anyway.

Check fuel levels with clear tube and check synchronization. Still think it's lean pilot.

EDIT TO ADD:

Is that a straight pipe in the picture? That will run REALLY lean.

all depends on the pipe the carbs and the way that you ride it
if you have a good scavange pipe and small carbs
and run it hot
then flood the pipe and shut the carbs down
the pipe will scavange unburnt fuel and flame and cause a loud pop
what carbs and what pipe you running?
How are you riding it?
also you are golden until a cop says thats too loud
which wont happen any time soon

As for my pipes, it is a straight pipe, but i put a baffle in it to increase back pressure. I have a custom highrise system in mind, but gotta get the seat done first. Nothin like riding 50 miles on metal. I synced them right after i took them aprt and everything. I have vacuum gauges, but I 'll try it again. Fuel level is good too, checked that wen they were off.

"also you are golden until a cop says thats too loud" lol that'll never happen in my town, not with all the rednecks and thier stright pipe trucks driving around me. I ride pretty low key, just crusin around with the ocassional 100MPH rush . Last time I checked my plug it was a little rich, and I tried the piolet jet and it didnt help.

I pulled the plugs yesterday after a 45 minute ride on the hiway and leting it idle a bit at home and both plugs looked about the same, a very light brown maybe a tad lean. Only difference was the one that pops had black soot on the ring of the thread bottum and the threads had oil on them. Side note- maybe bad rings?
anyway, the bike seemed a little reluctant to idle when I pulled into the drive, and I've always had problems with overheating, so I think that was the case there.

"bump"

You running the right plugs? The twins use the B6ES plug.

Only difference was the one that pops had black soot on the ring of the thread bottum and the threads had oil on them. Side note- maybe bad rings?

These things are notorious for bad valve guide seals and then the oil runs down onto the plugs after you turn the engine off.

Guess how I know.......

Maybe bad rings, but bad seals are likely too.

Thanks for the heads up. I'll have to take the head off to replace those wont I?