Cylinder 4 not firing

[OakraiderzGs1000]

Can someone explain how I test my coil with an ohm meter?

I have a 1979 gs1000e. Only the #4 plug isnt firing.
Is the coil my only concern?

[SPARKSS]

Can someone explain how I test my coil with an ohm meter?

I have a 1979 gs1000e. Only the #4 plug isnt firing.
Is the coil my only concern?

The plugs are paired 2 to a coil........you have 2 double ended coils, one which has plug #1 on one end and #4 on the opposite end. For #1 to fire well there has to be a path through #4 as they're in series. For a single cylinder to appear cold or not firing, (assuming it was an abrupt change), the most likely thing is that #4 plug is fouled. Replace it (and don't run it until you do as that cylinder will keep getting raw fuel, washing down it's cyl walls and probs associated). A fouled plug can be a good conductor at HV, just useless for it's intended purpose!

A second scenario for this to happen is that #4 wire is grounded or has broken insulation in close proximity to the head causing that to be the easiest way to complete the circuit (you might have occasional or poor firing).

A worse situation is that you've lost compression on #4 and the plug IS firing but contributing nothing (appears dead). Alternately, it's possible that #4 carb has plugged completely and will not fuel #4......the plug is firing and you have compression, but it's not contributing to engine power.....

Check the fouled plug first.......had one myself a couple of weeks ago for no ongoing reason........changed it and all was fine.

[OakraiderzGs1000]

Thanks for the advice.
I will try a new plug first.
It is definatly fouled. I can smell the gas on the plug. so I can rule out the carb I think.
The second senario could be the culprit. The boot on the wire is broken.
How hard is it to change the wire on the coil?
Or should I just replace the coil?

[SPARKSS]

Thanks for the advice.
I will try a new plug first.
It is definatly fouled. I can smell the gas on the plug. so I can rule out the carb I think.
The second senario could be the culprit. The boot on the wire is broken.
How hard is it to change the wire on the coil?
Or should I just replace the coil?

The wire might or might not come out of the coil predictably. If you're thinking of getting another coil, then try to remove it.....nothing ventured nothing gained! The boots on the plug ends are quite replaceable......NGK p/n is XB05FP for the inboard cyls (2 & 3) and VB05FP for the outer cyls (1 & 4). These boots have a built in 5k ohm resistance. Resistance for the coils 4.5 ohms primary, 10 to 11 k secondary (less plug boot resistance). This info describes my 79 GS1000 with point ignition.

[aosmith]

The coil and wire aren't actually meant to come apart... you could be fouling plug #4 because you're running way rich on one cylinder.

[OakraiderzGs1000]

Okay.
I'm gonna start with buying new coils.
Upon inspection, wire on #4 is old and cracked.

Can you guys reccomend aftermarket new coils?
And where to get them?

[n1elkyfan]

When I replaced the plugs on my bike I actually cut some of the plastic to get to where the actual wire was attached. Then I just used some waterproof epoxy to seal everything up.

[aosmith]

Check ebay for the coils... and honestly i wouldn't recommend trying to repair anything in there. Keep in mind resistance is key and if you dont connect it right etc etc you can increase the resistance and cause serious problems. I can't even imagine what havoc a short in there could cause

[txironhead]

Dyna "green" coils are the general consensus wonder coils for these bikes.