[quantumVista]

Vitals:

1982 KZ500C3 LTD
6-speed
30000mi
New plugs
new oil
mobil premium gas
new air filter
WAS RIDING FINE

Description:

After starting the engine and warming it up well say 5 -10 minutes the exhaust headers on Cylinder 2 & 3 are cold.

Observations

No spark!

Measures taken:

I followed the Clymer manual procedure for determining spark, and sure enough both are dark. I think it might be a coil. Funny thing though after the motor warms up the exhaust headers warm up too. Just about as hot as the other headers.

Tested both leads with new & known good plugs. No spark.

Question

Should I proceed one step at a time, replacing the caps, leads, then the coil? Or would you guys suggest, nabbing a new coil, OEM or aftermarket, to get her sparking again?

Thanks in advance

QV

for reference please view thread entitled KZ550C3 LTD Dies when clutch engaged.​

 

[QKENUF4U]

if i remember right coil 1 will fire cylinder 1 & 2 and coil 2 will fire cylinder 3 & 4 so its not the coils.
im thinking you have clogged pilot jets on 2 & 3 cylinders BUT its weird that they warm up after awhile. i would get a manual and go thru the carbs and make sure everything is to spec (float height esp., clean out the jets,check the diaphrams etc.)
good luck

 

[molebaby]

QKENUF4U One coil fires 1&4 the other coil fires 2&3.

 

[QKENUF4U]

QKENUF4U One coil fires 1&4 the other coil fires 2&3.

ah couldnt remember i knew it was one way or the other. :-?
as for his problem...........
do you know if you have SPARK on those cylinders ? are the plugs WET when you pull them out ? what color are they ?

 

[molebaby]

quantumVista
Swicth the wires from the wiring harness that go to the coils. Change 1-4 to 2-3 and 2-3 to 1-4.
Now with sparkplugs out of the motor check for spark at the plugs.
If coil 1-4 have no spark and 2-3 do have spark then I think your trouble is with the pickup coil on the stator plate.
If you have no spark at 2-3 and spark at 1-4 it could be Coil, caps or wires, do a resistance check.
I would replace the cheapist parts first.
If they all spark I have no more Ideas, ;-)

 

[quantumVista]

Yeah,

I followed the Clymer Manual procedure to check spark on all four plugs. Swapped leads and plugs too.

1 and 4 are hot, 2 &3 cold. NO SPARK

 

[QKENUF4U]

sounds like either the coil died or you lost the pickup (triggers the coils) do the coil swap and check to see if the cold cylinders switch.
good luck

 

[quantumVista]

coils swapped

I switch the power leads between the two coils and tried it out with the plugs out, no spark. I don't think the plugs were touching the block though. I may have to check again.

 

[QKENUF4U]

plugs have to be grounded to spark.