Losing spark #1 - diagnosed bad igniter

[Giblet]

Cylinder #1 has been losing fire on my 81 1000G. I finally tracked the problem down to the igniter. I have the igniter off my 82 1100GK but have discovered a difference in the igniters and the type of pick up on the signal generator. Is there a way to make the GK set work on the G assuming I can find a place to mount the GK igniter since it is twice the size of the G igniter?

[earlfor]

If cylinder #1 is losing spark and cylinder 4 is normal, the problem is not the ignitor, Anytime an ignitor goes out, you loose two cylinders.

Earl

[Giblet]

OK, so I put 1.5 volts (D cell battery) across the blue & green wires coming from the igniter to test it like the Clymer manual said and neither #3 or #4 plug fired. Is it possible to lose one cylinder out of a coil (ie coil bad)? I have nearly new NGK plug boots and the wires/coils are only 3 years old. Suzuki OEM coils.

I cylinder #1 is losing spark and cylinder 4 is normal, the problem is not the ignitor, Anytime an ignitor goes out, you loose two cylinders.

Earl

[SPARKSS]

OK, so I put 1.5 volts (D cell battery) across the blue & green wires coming from the igniter to test it like the Clymer manual said and neither #3 or #4 plug fired. Is it possible to lose one cylinder out of a coil (ie coil bad)? I have nearly new NGK plug boots and the wires/coils are only 3 years old. Suzuki OEM coils.

I'll assume you mean that you applied 1.5vdc to the input to the ignitor (to simulate the pickup coil)....ignitor on the bike etc. As Earl correctly pointed out, cylinders 1 and 4 are paired and use one coil while cylinders 2 and 3 are likewise paired and use the other coil. If you can switch one coil correctly then you should have the 2 cylinders associated, firing. If you only have one (as you've indicated) then I'd check for a loose or bad wire, bad plug cap (you may have to substitute to find this) or even a bad plug (I'll assume you've tried this).

How do you know you don't have firing on the suspect cylinder? Did you have the plug laying on the engine and connected while cranking or running OR did you remove the wire with the engine running to find that there was little or no contribution?

Food for thought

[earlfor]

No, each coil fires two cylinders simultaneously. If #1 is firing, there has to be fire on #4. If #2 fires, #3 must also. #3 and #4 are on differenct coils, so if both coils are inoperative............... the bike would not run or start. :-)

I would remove all four spark plugs. Re-insert the plugs into the plug boots.
One at a time, ground the spark plug threads to the cylinder head, press the starter and check for spark on the plug gap. I will assume you dont have black, oily deposits on the spark plugs that could cause them not to fire. Clean plugs? On the plugs that do not fire, I would unscrew the plug caps, trim 1/4 inch off the end of the plug wire and screw the caps back on tightly. If you are using the graphite core plug wires, it is very easy to get a poor connection at the plug cap. I'm inclined to think you have a spark plug problem or a plug boot to plug wire connection problem.

Earl

OK, so I put 1.5 volts (D cell battery) across the blue & green wires coming from the igniter to test it like the Clymer manual said and neither #3 or #4 plug fired. Is it possible to lose one cylinder out of a coil (ie coil bad)? I have nearly new NGK plug boots and the wires/coils are only 3 years old. Suzuki OEM coils.

[Giblet]

What you are saying makes sense looking at the wiring diagrams. The 1.5 volts was applied across the signal generator leads on the igniter. I just changed gaskets & valve guide seals on the top end. The main symptom is the #1 plug is quickly carbon fouling. Not oily at all. Plus, header pipes 2-4 are a slightly darker color (indicating more heating to me). Plug color looks normal on 2-4 as well. Gas mileage is just barely 31 mpg.

The plug was cleaned each time and it was laying on the case when I looked at the spark. Spark looked very weak and not blue like I would expect it to be. I did leave the plug wire off accidentally and the effect was not as noticable as I thought it should be.

I'll try clipping the wire and reattaching the boot.

[SPARKSS]

What you are saying makes sense looking at the wiring diagrams. The 1.5 volts was applied across the signal generator leads on the igniter. I just changed gaskets & valve guide seals on the top end. The main symptom is the #1 plug is quickly carbon fouling. Not oily at all. Plus, header pipes 2-4 are a slightly darker color (indicating more heating to me). Plug color looks normal on 2-4 as well. Gas mileage is just barely 31 mpg.

The plug was cleaned each time and it was laying on the case when I looked at the spark. Spark looked very weak and not blue like I would expect it to be. I did leave the plug wire off accidentally and the effect was not as noticable as I thought it should be.

I'll try clipping the wire and reattaching the boot.

Ok Gib.......this makes a lot more sense. First of all, once those plugs get fouled, even though you see a spark across the gap while out under atmospheric conditions, it's likely a fair part is also following the carbon - quite hard to clean effectively (best to put in a new plug.....once the problem is determined). Poor power contribution on #1 is a confirming symptom. Sounds like #1 may be over fueling.......AND/OR #1 is down on compression - note that if #1 is over fueling, this causes the cylinder walls to become washed down (from having a normal oil film) which reduces compression - so you can see how it can be a degenerative process. The last key is the high fuel consumption......my 79 GS1000 when in good tune typically gives me 45 mpg driven legally (well sort of).....and drops to 40 if I've developed a death wish. Although disconnecting one plug wire at a time while looking for cylinder contribution seems counter-intuitive because of the paired cylinders, it is valid - spark continues to occur (albeit a bit less) on the connected wire because the circuit is completed with capacitive coupling on the disconnected wire. Good to note that pipe temp but bear in mind that the center cylinders will run hotter anyway.....an IR gun is a better tool here (in conjunction with what you've already done).

Hope this helps.

[Giblet]

OK, so I put the igniter back on, clipped a bit off the wire and reattached the boot. Compared spark between 1 & 4. They look essentially the same. Remove #1 plug wire and there is no discernable change. Remove #2, #3 or #4 and the bike idles rough & eventually dies. I've checked (& set) float level on all 4 and I am certain they are dead on. Now, after some idleing in the garage, I decided to pull the plug before hitting the road and it is wet with gas. Guess its back into the carb. What effect would leaving out the rubber passage plug have I wonder? :???:

[Giblet]

Sounds like #1 may be over fueling.......Hope this helps.

Yep. Who knew a loose pilot jet was such a big deal ? I'm sure this is my wife's fault somehow :???: .

[SPARKSS]

Yep. Who knew a loose pilot jet was such a big deal ? I'm sure this is my wife's fault somehow :???: .

(grinnin here)....glad you're back on track. I'll suspect you won't be as well fed if you try to offer up THAT last comment though

[Giblet]

She's used to it . Besides, if I started taking responsibility for my actions now, she'd think I was having an affair or something. Like I've got time for that with all this GS stuff going on \\/ .

(grinnin here)....glad you're back on track. I'll suspect you won't be as well fed if you try to offer up THAT last comment though

[Steve]

She's used to it .

Yeah, she may be used to it, but that doesn't mean she enjoys it. :shock:

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