TOPIC:

So after i bought a 1976 kz900 4 days ago that  looks nice and restaured i need help with a few strange things i found
when inspecting the bike. when i rode it home it runs on 3 cyl i know it is cyl 1 because the downpipe does not get hot.It also backfired an had low power I changed all 4 sparkplus
 to ngk  B8es also the plugcaps 5 ohms .Then i drained the carbs from fuel that is 1 year old.Drained into a plastic jar
to see if there was any rust dirt coming out.The fuel look a litte greenbrown but it was minimal with dirt or rust coming out.I then flushed the carbs
with wd-40 and then fuel to losen up any crud that may stuck in the needlefloatseats.I will ovehaul the carb next winter so this was just a quick check
Then i checked the mixture screws they sits under the carbs on this model. all was about 2and a half out.i reset them to 1 and a quarter out since i read somwhere that is the setting.okay enogh about that.

 Then used a multimeter and checked the coils first i measured the volt to the coils by put one end of multimeter into the red/yellow wire and the other to ground (i think i read about that in this forum) on the engine head the reading was 9.80v then measured the resistance on the primary and ht plugwires with the caps on .The right coil that is powering plug 1 and 4 it was 23.9 ohms the primary measured 4.8 ohms
and on the left coil to 2 and 3 plugs was 26 ohms and primary was 4,9 ohms

So to the question when i first started the work the plugwires for the left coil was connected to cyl 2 and 4 and the right was connected to 1 and 3 that must be wrong. So then i called a guy that is a kawasaki guru and he says that left coil goes to 1 and 4 and right to 2 and 3.I tried that but the bike did not start and sometimes it backfired.Then i took off the
ignitioncover to take a look at the timing and dicovered it had a electronic ignition installed. Can that be the reason for the strange wiring on the ht wires??  Anyway since it did not start and sometimes made backfire sound with the left coil to 1 and 4 and the right to 2 and 3 i switced the wiring so left coil goes to 2 and 3 and right coil goes to 1 and 4.Then it fired up and runs good . After what i have found the last days is that
left coil is suposed to go to 1 and 4 and right to 2 and 3 .but my bike is oposite. I have testridden the bike yesterday and today and it runs great with good power and no backfiring. So what is going on ? i have drawn a wire diagram how the coils is wired on my bike .Gosh this post got long sorry.
 

As long as one coil feeds 1 - 4  the other feeds 2 -3  and the corresponding LT wires are to the correct coil it doesn't matter which one is on the left or right.
It's only the mounting orientation that differs and is nothing that will affect the running regardless of points or electronic triggering.
Either way the bike will only run if the leads are on the correct cylinders.


 

Rolf1976_KZ900 wrote:

Then used a multimeter and checked the coils first i measured the volt to the coils by put one end of multimeter into the red/yellow wire and the other to ground (i think i read about that in this forum) on the engine head the reading was 9.80v then measured the resistance on the primary and ht plugwires with the caps on .The right coil that is powering plug 1 and 4 it was 23.9 ohms the primary measured 4.8 ohms
and on the left coil to 2 and 3 plugs was 26 ohms and primary was 4,9 ohms



 

Your coil supply voltage seems very low - what was the battery voltage when you measured the coil supply? The voltage on the yellow/red should be within 0.5v of the battery voltage. When measuring voltage use the battery negative terminal for your ground (any resistance in the ground line will distort your voltage readings) The best way would be to put the meter red lead on battery positive then with ign and kill switch on put the black meter lead to the yellow/red (this will measure the voltage difference between the battery and the coils) should read no more than 0.5v. 
Poor coil voltage is a common issue with these old bikes - the rational and the common used solution is explained in the below link

www.kzrider.com/forum/4-electrical/61751...-pass-relay-w#866730

zed1015 wrote:

As long as one coil feeds 1 - 4  the other feeds 2 -3  and the corresponding LT wires are to the correct coil it doesn't matter which one is on the left or right.
It's only the mounting orientation that differs and is nothing that will affect the running regardless of points or electronic triggering.
Either way the bike will only run if the leads are on the correct cylinders.


Thank you zed1015   That was clarifiing  so then i dont need to worry.Maybe someone mixed the coils putting them back on
 

Wookie58 wrote:

Rolf1976_KZ900 wrote:

Then used a multimeter and checked the coils first i measured the volt to the coils by put one end of multimeter into the red/yellow wire and the other to ground (i think i read about that in this forum) on the engine head the reading was 9.80v then measured the resistance on the primary and ht plugwires with the caps on .The right coil that is powering plug 1 and 4 it was 23.9 ohms the primary measured 4.8 ohms
and on the left coil to 2 and 3 plugs was 26 ohms and primary was 4,9 ohms





 

Your coil supply voltage seems very low - what was the battery voltage when you measured the coil supply? The voltage on the yellow/red should be within 0.5v of the battery voltage. When measuring voltage use the battery negative terminal for your ground (any resistance in the ground line will distort your voltage readings) The best way would be to put the meter red lead on battery positive then with ign and kill switch on put the black meter lead to the yellow/red (this will measure the voltage difference between the battery and the coils) should read no more than 0.5v. 
Poor coil voltage is a common issue with these old bikes - the rational and the common used solution is explained in the below link

www.kzrider.com/forum/4-electrical/61751...-pass-relay-w#866730

Thank you Wookie58   I will check again .i Think the battery was a little low on power because i had done some testing for sparks on all plugs and also a compression test .

 

By convention the left coil should power 1 and 4 and the right should power 2 and 3, but your wiring looks correct...black to 1 and 4 and green to 2 and 3.  Your primary coil resistances look OK.  The secondary...I hope you mean 23.9 and 26 THOUSAND ohms.  

Based on your wiring diagram I'm assuming there is no exciter in between the electronic ignition and the coils.  The voltage at the coils is low.  It should not be less than 1 volt below your battery voltage.  Check and clean all the connections.  There should be a third wire coming from the ignition that provides power. It will be hooked into one of your power wires...red or brown usually.  What is the power source for the electronic ignition?

The KZ900 did not come with fuel adjusters under the carbs, so someone has changed them at some point.  They may be off a 1977 KZ1000.  If they have a pump on the bottom of #2 carb they are newer than 1977.

Have you done a compression check on #1 cylinder?  Low compression could be a cause of your problem.

Are you getting fuel to #1 cylinder?  How does the plug look?  Is it wet?

If you have a Dyna S it will drain the battery quickly. I never leave it on without the bike running. It can also be damaged that way. Couple it with Dyna 3 ohm coils and the charging system can be taxed if not up to full power output. The Dyna S is a great system but it can be a power hog. 
Steve

www.kzrider.com/forum/4-electrical/61830...arging-issues#876944

Hello i have been very busy so hasent had time to reply but now i have checked some more stuff on the bikei only had the bike for 8 days so far and trying to get as much of information i can.The seller provided mewith a workshop manual and 2 great books about the kz models so that was nice.The bike has been very little usedthe last eight years, but had a big service 2019 done at a workshop i found resiepts of that.

Hardrockminer : thanks for info  on the coils looks like they are just placed oposite than normal then.when i measured the secondary resistance im not sure but i think  the multimeter knob was at 2000 ohmim no good at electrical stuff .But i know that when placing the multimeterknob at different ohm settings i gota open line reading.I have now tested all sparkplugs and they all have good spark with 5 ohm plugcaps .I tested if the spark was better if i installed a 1 ohm plugcap and it looked better,but i only bought 1 cap to test and dont know if itis healty to install 1 ohm caps with the electronic ignition that is installed on the bike?? anyway the bike now runs great .After running the bike for some days nowand had a look at the sparkplugs i did some minor adjustment to the fuel mixture screws  because it was running lean on cyl 4 and rich on cyl 1.  turned cyl 1 a quarter (15 minutes) in and cyl 4 a quarter out.  .The bike runs good now i will check the plugs again in some weeks.You are right the carbs are from a 1977 z1000A1.

Wookie58 : Thanks for teaching how to measure the volt to the coils the proper way. When i got the low 9.88vreading i connected to ground on the cylhead.Now after using the negative batterypost the reading was much better.Also cleaned up almost all electrical connections and used a little dielectric grease on them. several had a little rust or green deposits.Thans for the link to the relay fix i bought a set og headlight encance relay wiringloom thinkin i could use that to the coils,but now i dont think i need to install that.

SWest : I dont know what brand electronic ignition is installed i post some pics .The bike has a acid battery.By the way yesterday while doing a oilchange and stuff i found the venttube for the battery was only about 3 inch long.That will make acid drip on the frame so i replaced that with a long tube that goes all the way downto under the rearswing arm .Is that any issuse with doing that ? i mean maybe the long tube will make a vacumwhen riding sucking acid out of the battery?? 


 

Hi Rolf - it looks like you have the coil feed disconnected from the coil when you took the measurement, in this state there is no load on the circuit so may give an "optimistic" reading. (All voltage measurements should be taken with wires connected and the circuit in it's normal operating condition) If electrics isn't your strongest skill you might find the below fault finding guide useful. It's a little heavy but I tried to explain the "whys" with everything.

Electrical fault finding guide - KZRider Forum - KZRider, KZ, Z1 & Z Motorcycle Enthusiast's Forum

Ha Ha im not good when it comes to electrical stuff .I started to read your fault finding guide yesterday, but did not have time to read all. So how do i measure then? if the wires are connected where do i put the multimeter pins?

Rolf1976_KZ900 wrote:

Ha Ha im not good when it comes to electrical stuff .I started to read your fault finding guide yesterday, but did not have time to read all. So how do i measure then? if the wires are connected where do i put the multimeter pins?

You have a few options:

• Pull the connector back slightly on the coil terminal so you can get the tip of your probe onto the tag coming out of the coil
• Slide back the rubber cover over ther terminal (if possible)
• Insert your probe under the rubber cover from the back
• Make a jumper wire with a male and a female crimp connector that don't have the rubber cover so you can access the terminal (insert between the yellow/red and the coil terminal)

Wookie58 wrote:

 

You have a few options:

• Pull the connector back slightly on the coil terminal so you can get the tip of your probe onto the tag coming out of the coil
• Slide back the rubber cover over ther terminal (if possible)
• Insert your probe under the rubber cover from the back
• Make a jumper wire with a male and a female crimp connector that don't have the rubber cover so you can access the terminal (insert between the yellow/red and the coil terminal)

I have read your  suggestion many times now and have to admit that i dont get it

  I hawe juperwires with crock klamps.. can i just connect one end where the red/yellow wire is soldered on to the front of coil  and  the other end of the jumpwire to the multimeter probe .And then put the other probe from multimeter to battery negative post ?  
Update i did a drawing can the coil be tested like this ?