popping noise

I've noticed (in lower gears) some decel "popping"...is this related to fuel mixture? Or something else altogether? Where's the easiest place to identify and correct something like this? Also, I'm using 87+ octane - Am I safe with this type? I have an '82 KZ750 LTD.

Thanks for the help....

idle curcuit is a little lean

adjust mixture screws or install bigger pilot jets

The air injection system will cause that popping when the diaphragm valve ges defective. Try capping the ports on the op of the valve cover, and capping the vac lines going to the air switch above the motor.

It's likely the pilot jet is too lean but it can also be a vacuum leak.

Good advise so far...

If the engine is in a known good running condition state, and everything is stock - air box/stock filter, stock exhaust, then the stock # turns out on the mixture screws, and the stock jets will work fine in a clean set of carbs.

Dont start to change out jets. Additional air is getting into one, or more of the cylinders. Making sure that absolutely everything is air tight from the air filter to the exhaust tip is crucial to proper operation.

The carb to engine holders is the usual culprit, and a good cleaning and some Permatex motoseal, or #2 gasket maker will take care of that.

With the bike running, spray wd40 on the carb linkage and seals, etc. listen for rom change, and watch exhaust for black puff if any gets sucked in a leak.

Make sure the airbox conections/hoses are all air tight at the carbs. If they're dried up and hard, replace them.

Good luck.

Another thing that will make it pop is a leak at the exhaust header gasket where it goes on the engine.

I tightened my right side header clamp, and the slight popping, which I had on the right side while decelerating, went away. Don't tighten too much, though. Keep within torque spec.

I've had popping for three years in my KZ1100 - ever since I put it together. I've tried everything - new valves, pistons, rings, carb holders, vacuum caps, exhaust gaskets, larger pilot jets (twice), sealing off air recirculation system, adjusting float levels, adjusting fuel mixture screws, etc. Today I sync'd the carbs and used a ColorTune to see what was going on in the cylinders. After the sync there was still popping but even though it idled well there was no combustion in one of the cylinders - the plug was firing but no fuel was being burned. I adjusted the air (fuel?) mixture screw until that cylinder was firing at idle and the popping is gone. I'm pretty happy - the popping was really bugging me and it's gone. Did I mention that the popping is gone?

KYKZ1100 wrote:

I've had popping for three years in my KZ1100 - ever since I put it together. I've tried everything - new valves, pistons, rings, carb holders, vacuum caps, exhaust gaskets, larger pilot jets (twice), sealing off air recirculation system, adjusting float levels, adjusting fuel mixture screws, etc. Today I sync'd the carbs and used a ColorTune to see what was going on in the cylinders. After the sync there was still popping but even though it idled well there was no combustion in one of the cylinders - the plug was firing but no fuel was being burned. I adjusted the air (fuel?) mixture screw until that cylinder was firing at idle and the popping is gone. I'm pretty happy - the popping was really bugging me and it's gone. Did I mention that the popping is gone?

But what happened to the popping?

KYKZ1100 wrote:

Did I mention that the popping is gone?

If you later miss the popping sound you may want to put a tablespoon of unpopped popcorn in each muffer for old times sake. :silly:

Maybe I missed it but you didn't mention if the popping was gone?..... :laugh: :laugh: :laugh:

"Color-Tune to see what was going on in the cylinders. "...

Thank you, for an outsider (other than me) just proved once again why this is a handy tool to have around... You can see what's going on in the chamber....

How much more easier can that be in adjustments and T-shooting....

Old Man Rock wrote:

Maybe I missed it but you didn't mention if the popping was gone?..... :laugh: :laugh: :laugh:

"Color-Tune to see what was going on in the cylinders. "...

Thank you, for an outsider (other than me) just proved once again why this is a handy tool to have around... You can see what's going on in the chamber....

How much more easier can that be in adjustments and T-shooting....

+1 Agreed... Love that tool now, it saves me sooo much time.

Before, I would have to hold the rpm up slightly where an engine popped worst and crank more mixture into the cylinders via the mix screws to determine which cylinder/carb had an issue. Now I jsut throw in the colortune, and I can see immediately where I need to be/what to do, without an hours extra work.