81 KZ750H2

Hey Guys, I have put several post on here about this frustrating bike so here comes another!! I just got finished putting Dyna 2.2 ohm coils on it and that went fine. I am getting good voltage to them. This bike has a Vance and Hines exhaust on it with baffles in it and these goofy pod filters I have never even seen before! I have went through the carbs and the jetting I am presently at is stock pilots,65 primaries and 135 secondaries! The fuel mixture screw is at 2.5 turns out. The valve clearances are within spec and I did a leakdown test on all 4 cylinders and they were really good! This thing just can't sustain an idle after it heats up. I am 100% sure the carbs are spotless and the pilot jets are clear. I have rebuilt hundreds of carbs to this point and always have had superb idling. I even hooked my inductive timing light up to all 4 plug wires individual;ly while the idle is falling off and the flashes remain steady all the way until it stalls. The only thing I have yet to replace is the carb holders but I did spray WD40 and carb cleaner around them thoroughly and was no change! Does anybody have any idea at all what could cause this? I am at wits end with this thing! Let me know if you need any more info!

You say that the idle becomes rough once it gets hot? Sounds just like my z650. I went through my carbs about 10 times thinking that i might have missed something, turned out to be a bad condenser in the points. Once quick way to check is to just grab any condenser and touch it to the old condenser. When I did so, the bike instantly started running smoother. There's a good chance that your problem is something different, but it took me forever to find out what my problem was. Hope its easier for you.

Sorry but this bike has electronic ignition. No points or condenser! Thanks for thr reply though!

If the pods are too small it will cause a rich condition and "flood" it out at low RPM.Try setting the idle around 1500 or so and see how it goes.With mods like a pipe/pods/jets you can't set the idle under 1200 or so.

lrburke wrote:

Hey Guys, I have put several post on here about this frustrating bike so here comes another!! I just got finished putting Dyna 2.2 ohm coils on it and that went fine. I am getting good voltage to them. This bike has a Vance and Hines exhaust on it with baffles in it and these goofy pod filters I have never even seen before! I have went through the carbs and the jetting I am presently at is stock pilots,65 primaries and 135 secondaries! The fuel mixture screw is at 2.5 turns out. The valve clearances are within spec and I did a leakdown test on all 4 cylinders and they were really good! This thing just can't sustain an idle after it heats up. I am 100% sure the carbs are spotless and the pilot jets are clear. I have rebuilt hundreds of carbs to this point and always have had superb idling. I even hooked my inductive timing light up to all 4 plug wires individual;ly while the idle is falling off and the flashes remain steady all the way until it stalls. The only thing I have yet to replace is the carb holders but I did spray WD40 and carb cleaner around them thoroughly and was no change! Does anybody have any idea at all what could cause this? I am at wits end with this thing! Let me know if you need any more info!

What ignition system (stock)?

After stalling out, will engine immediately crank and run again? Or does it need to first cool before it will again run?

Will engine continue running normally while riding the bike unless permitted to idle? In other words, would it run just fine for say a straight stretch of 50 miles, and everything be okay until coming to a halt at idle?

Was suspicious of valve clearances until reading that they were to specs. (Still a little suspicious.) :lol:

Good Fortune!