testing coils

have a misfire on 1+4 but 2+3 are working great. want to test coils without using a multimeter, but the spark plug cables are too short to switch 2+3 > 1+4.

can i just switch the white connectors from the harness that go to the coils or will that screw things up?

 

I am having spark issues as well, these links might help

http://xjbikes.com/Forums/viewtopic/t=6 ... rical.html

http://xjbikes.com/Forums/viewtopic/t=21932.html

 

yes you can swap the harness connectors. but it's easier to troubleshoot the way it's outlined in the troubleshooting guide above (swap wires right at the TCI). start at step 5.

 

thanks tibor. that thread is perfect!

unfortunately, i can't figure out what im doing wrong with my multimeter.

I'm testing the resistance in OHMS across the primary coil by placing one probe on one side of the coil harness connector and the other probe on the other side.

my multimeter doesn't read anything however. it just displays its 1. does the same thing on my known good coil too, and the plug caps.

i'm putting one probe on the spark plug side and one probe on the wire screw side and still no reading. same on all caps.

I've tried the multimeter on all the OHM settings and same results.

the ignition is on, battery charged. batteries in the multimeter are fresh too.

What gives? am i a bit slow?

 

what does it show when you touch the probes together? should read 0 ohms or something like 0.01 ohms depending on the scale.

 

it reads 1 on all settings... i think its toast. grr

 

one of the steps i did with my yamaha is hook up the voltmeter to the coils. positive to the power side, negative to ground.

voltage would be in and out as the coil was turning on and off.

in other words. you should see voltage fluctuations.

the pickup coil is what does the triggering to the coil. via the tci box.

if your not getting voltage to the coil. it could be the ignitor box. if you got voltage and it's not fluctuating. suspect the pickup. if you got volttage and it's fluctuation. suspect the coil. or bad ground for coil.

my latest bike i just picked up had no spark in one cylinder. VTWIN motor.
the cap wasn't connected properly inside the wire. spark was arcing and burning up the wire conductor and cap terminal. cap terminal was black. i cut the wire down 2 mm. screwed the cap back on. problem solved.

you might not be so lucky though. with 2 cylinders on one coil.

 

The problem with ohm meters is, you can't use them while there's power on the circuit, or they blow up. Just for future reference if you're measuring resistance, make sure to disconnect the + (It's a clip by the battery, easy to do)

 

gotcha.

i tested the coils and they're good on the primary. secondary gave no reading however, and neither do the plug caps. gonna run thru the diagnostic test above and see where i get.

thanks!

 

before i start testing, i get spark on all four cylinders, just piss poor firing on 1+4. we shall see, im going to do all the tests anyway

 

I have spark on all four. all looked to be about the same brightness.

coil primaries test at 2.8 ohms for both coils.

when i try to test the secondary coils, i get no reading. one probe in 1/2, one probe in 4/3 spark plug wire w/o cap.

when i try to test the plug caps, i get no reading. one probe on inner contact, one probe on screw contact.

the procedure outlined in the schematic above says i should switch the orange and grey wires at the 4pin tci connector and see if the lack of spark switches from 1+4 to 2+3 or vice versa. this is impossible for me to do since i have spark on all four.

I watched the combustion using a colortune tool. 2+3 ran rich but fired every stroke.

1+4 very rarely fired (read:misfire) with combustion color ranging from white blue to orange. white blue more often on the misfires (makes sense, wasted spark igniting remaining unburnt fuel)

any suggestions as to what is going on?

 

I had the same problem on my 83 XJ750. I had a good spark on 1+4 but weak on 2+3. I also had high resistance on the caps for 2+3. I replaced the coils with Dynatech ones from chacal, also replaced the caps. Had no more trouble.

 

1 and 4 cylinder plug caps get tested together. 2 and 3 cylinder get tested together. using both probes.

you should have 22,000 ohms between plug caps 1 and 4. 2 and 3. youir checking resistance from cap to cap through both wires.

so you put one probe in one cap. other probe in other cap. MOUNTED TO THE WIRES. your checking the resistance between both caps and wires.

the caps by themselves should ohm out at 5,000 ohms. 2 and 3 should be 10,000 if y ou have stock caps.

2 wires by themselves should be 11,000 ohms.

 

All XJ's are not created equal:


Ignition system components resistance specifications:

The following list also covers the resistance values of the spark plugs, plug caps, and the ignition pick-up coils (which are located behind the left side round crankshaft end cover). The resistance of the pick-up coils can be checked at their connector to the TCI box by measuring the resistance between the grey and the black wire (this checks the condition of the first pick-up coil) and then between the orange and the black wire (this is the resistance of the other pick-up coil).

NOTES:

- On the pick-up coils, the orange lead wire is the trigger wire for the #1/#4 ignition coils, while the grey lead wire is the trigger for the #2/#3 ignition coils.

- The ignition coil for the #1/#4 spark plugs is mounted on the left side of the bike, and has the solid orange (ground) wire and the red-with-white-tracer-stripe (hot) wire input leading to it.

- The ignition coil for the #2/#3 spark plugs is mounted on the right side of the bike, and has the solid grey (ground) wire and the red-with-white-tracer-stripe (hot) wire input leading to it.

- "K" is abbreviation for a thousand units, so "5K" ohms = 5,000 ohms of resistance, etc.

- Ignition coil secondary ("the plug wires") resistance should be measured with the spark plug resistive caps removed. The plug caps themselves should be measured separate. In this manner, you can pin-point the source of a problem----coils, caps, both, or neither!



XJ550 models:

Pick-up coils:
650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range


Ignition Coils:

Primary side (input from main wiring harness):
2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range


Spark plug caps:
10K +/- 20% = 8,000 to 12,000 ohms per cap acceptable range


Spark plugs:
0 ohms per plug




XJ650 models:

Pick-up coils:
1980-81 XJ650 Maxim and Midnight Maxim: 700 ohms +/- 20% = 560 ohms to 840 ohms acceptable range
1982 XJ650RJ Seca (non-yics engines): 700 ohms +/- 20% = 560 ohms to 840 ohms acceptable range
1982-84 XJ650 Maxim: 650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range
1982 XJ650RJC Seca (yics engine): 650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range
1982-83 XJ650 Turbo: 120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range


Ignition Coils:

Primary side (input from main wiring harness):
2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range


Spark plug caps:
5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range


Spark plugs:
0 ohms per plug




XJ700 air-cooled models:

Pick-up coils:
120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range


Ignition Coils:

Primary side (input from main wiring harness):
2.7 ohms +/- 10% = 2.43 ohms - 2.97 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
12K ohms +/- 20% = 9,600 ohms - 14,400 ohms acceptable range


Spark plug caps:
1985 N/NC models: 5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range
1986 S/SC models: 10K +/- 20% = 8,000 to 12,000 ohms per cap acceptable range


Spark plugs:
1985 N/NC models: 0 ohms per plug
1986 S/SC models: 5K ohms per plug




XJ700 water-cooled models:

Pick-up coils:
120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range


Ignition Coils:

Primary side (input from main wiring harness):
2.7 ohms +/- 10% = 2.43 ohms - 2.97 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
12K ohms +/- 20% = 9,600 ohms - 14,400 ohms acceptable range


Spark plug caps:
10K +/- 20% = 8,000 to 12,000 ohms per cap acceptable range


Spark plugs:
1985 XN/XNC models: 0 ohms per plug
1986 SX/SXC models: 5K ohms per plug




XJ750 air-cooled models:

Pick-up coils:
650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range


Ignition Coils:

Primary side (input from main wiring harness):
2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range


Spark plug caps:
1981-83 models: 5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range
1984 RL models: 10K +/- 20% = 8,000 to 12,000 ohms per cap acceptable range


Spark plugs:
0 ohms per plug




XJ750 water-cooled models:

Pick-up coils:
120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range


Ignition Coils:

Primary side (input from main wiring harness):
2.7 ohms +/- 10% = 2.43 ohms - 2.97 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
12K ohms +/- 20% = 9,600 ohms - 14,400 ohms acceptable range


Spark plug caps:
15K +/- 20% = 12,000 to 18,000 ohms per cap acceptable range


Spark plugs:
5K ohms per plug




XJ900RK, RL, N, FN, and F models:

Pick-up coils:
120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range


Ignition Coils:

Primary side (input from main wiring harness):
original coils, marked CM12-20: 2.7 ohms +/- 10% = 2.43 ohms - 2.97 ohms acceptable range
replacement coils, marked CM12-09 or CM12-10: 2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
original coils, marked CM12-20: 13.2K ohms +/- 20% = = 10,560 ohms - 15,840 ohms acceptable range
replacement coils, marked CM12-09 or CM12-10: 11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range


Spark plug caps:
RK and RL models: 5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range
N, FN, and F models: 10K +/- 20% = 8,000 to 12,000 ohms per cap acceptable range
S and SH models: 15K +/- 20% = 12,000 to 18,000 ohms per cap acceptable range


Spark plugs:
RK and RL models: 0 ohms per plug
N, FN, and F models: 5K ohms per plug




XJ1100 models:

Pick-up coils:
120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range


Ignition Coils:

Primary side (input from main wiring harness):
2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range


Spark plug caps:
5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range


Spark plugs:
0 ohms per plug

 

thanks for the info everyone. @ snowwy: i got all that, but i don't get a reading on my multimeter when i do the prescribed tests. just stays at one for both coils, and i know at least one of the coils is good.

same for plug cap resistance; the meter doesn't read anything on any of the plugs.

Don't have time to work on it today; I'll get out there on monday and see if i can get any of the tests to work. why would the meter not read anything (it just stays on its default display)?

@ chacal: which tci connector has the pickup connections in it? 6 pin or 4 pin?

im really confused as to why my multimeter will give me a solid reading when i test the primary coil, but no reading at all when i test anything else (secondary, plug caps etc.)

 

I have a XJ650 that I've been trying to figure out why it takes so long for it to start. It has spark but just for ha-ha's I decided to test the spark plug coils and I get no reading. I've tested the pickup coils and they read in spec.

 

old thread.
how did you test ignition coils ?

if it starts your coils are likely good.

if your battery is low/bad bike will be hard to start

give us some history on your bike maybe start your own thread on your bike and fully ID it for us. year and model ?