KZ1000 Miss at 3800 RPM

Adjusted my valves and buttoned everything up. Started fine and below about 3800 rpm everything is fine. But at about that point, it feels like I am losing 2 cylinders and it barely runs (and doesn't gain rpm). Swapped out my plug wires since they weren't too good. but didn't help. Was going to change the plugs next. Any thoughts/guidance is appreciated. Thank you!

grumpy56 wrote:

Adjusted my valves and buttoned everything up. Started fine and below about 3800 rpm everything is fine. But at about that point, it feels like I am losing 2 cylinders and it barely runs (and doesn't gain rpm). Swapped out my plug wires since they weren't too good. but didn't help. Was going to change the plugs next. Any thoughts/guidance is appreciated. Thank you!

How did it run before you adjusted the valves? Did you recheck evrything that you touched?

It ran fine before I adjusted the valves. Can't really think of anything that I may have altered during the valve adjustment. My guess is it is something electrical since it seems to occur within the same rev band no matter what position the throttle is in.

the odds that something went south electrical at exactly the same time you did valve adjustment seem pretty long to me....i know you are not a rookie, but i would go back in and recheck...we all make mistakes..i did a valve adj once and bike wouldnt start..check for spark nada..the red wire for dyna came undone wrestling h-cover back on...quite the shotgun blast when i hit the button with fueled up cylinders...:laugh: ..just my .02....keith

keith1 wrote:

the odds that something went south electrical at exactly the same time you did valve adjustment seem pretty long to me....i know you are not a rookie, but i would go back in and recheck...we all make mistakes..i did a valve adj once and bike wouldnt start..check for spark nada..the red wire for dyna came undone wrestling h-cover back on...quite the shotgun blast when i hit the button with fueled up cylinders...:laugh: ..just my .02....keith

..

yeah somthing like that i was thinking and asking questions and finally i took my harness all the way off one zip tie at a time and found where my problem was this time (dif all the time...lol)you got somthing unplugged or just barley plugged in is my 2 cents...i just had a close deal on mine....good luck,,,mine was a coil/plug wire that worked loose and was jumping the spark and sputtering...this time:laugh:

Check the ignition advancer on the right side of the crank. If it's stuck and not able to move freely this might be it.

trianglelaguna wrote:

keith1 wrote:

the odds that something went south electrical at exactly the same time you did valve adjustment seem pretty long to me....i know you are not a rookie, but i would go back in and recheck...we all make mistakes..i did a valve adj once and bike wouldnt start..check for spark nada..the red wire for dyna came undone wrestling h-cover back on...quite the shotgun blast when i hit the button with fueled up cylinders...:laugh: ..just my .02....keith

..

yeah somthing like that i was thinking and asking questions and finally i took my harness all the way off one zip tie at a time and found where my problem was this time (dif all the time...lol)you got somthing unplugged or just barley plugged in is my 2 cents...i just had a close deal on mine....good luck,,,mine was a coil/plug wire that worked loose and was jumping the spark and sputtering...this time:laugh:

You might think about checking the wires under the gas tank. It is easy to bump something while taking the tank off and on.

grumpy56 wrote:

...Swapped out my plug wires since they weren't too good. but didn't help....

What type plug wires, caps, and ignition coils are presently fitted? (Am thinking oem coils had permanently embedded plug wires). Perhaps a faulty component and/or faulty connection, such as, coil>plug-wire, plug-wire>cap, and/or cap>plug.

What type of ignition is presently fitted? (oem with igniter; Dyna-S; something else) ?

Has ohm reading been done on coil circuits, both primary and secondary?

With engine running in dark area (eg., unlighted garage at night), could spray water mist (use common hand-held household spray bottle) all over top area of engine (coils, plug wiring, caps and plugs) to determine whether there's leakage in the hign tension circuit (look for arcing sparks).

What is measured positive battery voltage at coil primaries with engine off and ignition switch in ON position? (Thinking possibly insufficient voltage to coils for whatever reason).

While changing to brand new spark plugs, would visually inspect spark quality on each new plug before installing it.

Good Luck!

Thanks to you all for your inputs. Will check the advancer and then walk through each of your suggestions. 80 degrees here today and perfect for a KZ ride.

Cleaned and greased the advancer, but no improvement. I recall depressing one of the air sunction valves and it didn't quite seem to close fully at first, then was OK. Could that cause this condition? Thank you.

One more clue if I may...when I finally was able to get it over 5500/6000 RPM it pulled like a champ. The stumbling appears to only occur between 3800 and 5500 RPM.

did ya mess with carbs at all?