Topic: Strange popping and smoke

[1979CB650_Chris]

Hey all,

Occasionally I will start off from a traffic light, or accelerate really hard and I will hear what sounds like a muted backfire or a popping noise.  Or I will be cruising on the highway and I will hear this popping noise.  It will usually start after the bike has been warmed up.  Also sometimes when it pops there is white smoke that will start coming out.

Anybody got any ideas?  Thanks Chris

[ProTeal55]

Lean is mean 
Might need a bit more fuel up top.

[8 Track]

Maybe only one cylinder is lean... or rich.  When it starts doing that popping thing, try pulling the choke to see how it changes; gets worse or goes away.  Of course, you throw the other three cylinders out of kilter, so it's a hard test to carry out.  Where's the backfire coming from?  Intake side, or exhaust side?  Intake side's usually lean and exhaust side is usually rich.

[keiths]

Did you check the timing? How about a plug chop?

[brewbrother]

Hey all,

Occasionally I will start off from a traffic light, or accelerate really hard and I will hear what sounds like a muted backfire or a popping noise.  Or I will be cruising on the highway and I will hear this popping noise.  It will usually start after the bike has been warmed up.  Also sometimes when it pops there is white smoke that will start coming out.

Anybody got any ideas?  Thanks Chris

Just an opinion but I think carb balance is off.

[heffay]

yes he does.  and could be right.

especially if you think about what we are talking about... one cylinder being lean and all and, trying to figure out which one it is...

 

[Lumbee]

...also an exhaust leak can cause popping, especially on decel.  Make sure u'r pipes have a good seal at the head...