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#21 · (Edited)
With more reflection on this one, I think that UTP's comments have more gravity. Here's why: As I understand it, the ECU triggers a coil and each coil fires to a 'pair of cylinders' so, if this is correct and you're certain that 'one' cylinder is misbehaving then a specific coil or ECU can't be the fault but instead, the fault must lie in the wire/spark plug cap end of the system.

As a troubleshooting method, if you discover which cylinder is misbehaving, you can swap leads with the other wire off the same coil to check if the 'problem' moves with the wire change. Now, depending upon the length of the plug wire and the affected cylinders, this may or may not be simple to do.

Anybody else confirm or deny this logic? (I sure don't want to give bad advice here!) :dunno
 
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Discussion starter · #22 ·
That def seems to make the most sense, trying to figure which cylinder is the one with the issue is the problem, but I'm 99.9% sure its only one cylinder acting up from the sound of it at idle and how it performs while riding it.

If its just a wire is what I'm worried about, I have never seen wires sold individually as they are attached to the coil pack. Maybe just a spark plug cap needs to be replaced, but the thing is I have tested each one for continuity and for spark and all 4 DO spark, this is why its so frustrating trying to narrow down what the problem is.
 
#23 ·
I have done it and it is a very delicate operation because of the tiny plastic (read: delicate) retainer clips that hold the spark plug wire to the stock coil, have you considered replacing all four wires with an aftermarket wire?

A relatively 'cheap' fix but it also might help to eliminate the problem. I used a twisted wire core NGK wire with a red insulation jacket on it (none of that 'radio interference suppression core' stuff - looks great and works great! Just be real careful with those little clips - they break real easy!! (that's personal experience speaking!).
 
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#24 ·
The coil packs fire 1,4 and 2,3. They hit a spark even if the cylinder is not on it's compression stroke. If your plug wires are long enough you can swap the leads around from 1 to 4 and then 4 to 1. 2 to 3 / 3 to 2. It won't make a difference. At least with that you can see if the dead cylinder follows along with a particular plug wire.
 
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#25 ·
If you know how to use a Ohm meter you can check the resistance in the sparkplug cap.
I don't know how much it should be does anyone else?
How to test it is simple.Disconnect the plug cap from the spark plug wire. Then meassure from the end where the wire enter and inside the plug cap were the sparkplug connects.
 
#26 ·
There is a simple tool you can buy at your auto parts store that you place on the outside of the wire that will pick up the spark signal and flash to show you if there is high tension current running through the wire, it will pulse with the spark signal. They are about $10. I looked up the coil resistance of my wifes 250 ninja and the primary resistance is 2 - 3 ohms ( measure pos and neg in to the coil, take the wire leads off) and 10-16 kilo-ohms on the secondary side (negative in and end of the plug wire). Not sure if they are the same on a Suzuki or not but it's a start unless someone else has a manual to tell you the specs. Her manual also mentions an ohm test tor the CDI ignitor to test if the unit is also within spec. Basically get a manual and you can test all the parts you suspect. I'd also look into the wires themselves. The resister core wires have a graphite core that can fail with age. Maybe check the resistance with the wires hot and cold to see if there is a drastic change. My old boss had some old wires on his car and a horrible stumble on idle. He opened the hood at night and you could see the spark exiting the wire to the engine block half way along the wire, it never reached the plug. The wire looked fine, you would never know it was damaged. As an experiment, try opening your gas cap before you start your bike. You may have a suction air lock in there. Maybe just enough to restrict some fuel flow. This happened to the wifes bike, had to clean the vent in the fuel cap before her bike would run for more than 15 seconds. When the gas is warm you may have enough tank air flow to sustain fuel flow but when the gas cools off the air pressure drops and if the vent is plugged it can hold a slight vacuum. Good luck.
 
Discussion starter · #27 ·
I appreciate all the advice guys, I think I am going to buy new 3 ohms coil packs and new 7 mm wires to replace the stock one I have on my bike, rather just avoid ever having this issue again in the future! Thanks again!
 
Discussion starter · #29 ·
Ok so I know its not a coil, its has to either be a wire or carb issue...usually when a plug keeps fouling out theres too much fuel in the cyl correct? Or could it be the wire going to that plug, b/c only cyl 3 keeps fouling plugs. But last year this time of year I had my bikes carbs cleaned balanced and dyno tuned, so I'm finding it hard to believe thats the problem, but I guess thats the only solution.

I'm not an expert at carbs by any means so what should I be looking for?
 
#31 ·
^^^ That is pretty weird dude!! Those other three plugs look fine and that one is just black!
 
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#32 ·
Are you positive you don't have a vacuum leak on the #3 carb. Does your 1100 have the little vacuum fitting on the #3 intake boot like the 750 or does it pull the fuel petcock vacuum from the top of one of the carbs?
 
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#33 ·
Did you happen to take the tops off the carbs to clean them, etc? There is a tiny o-ring under the cap that fits in the top of the carb body to seal the vacuum port. If that o-ring is missing you will pull air at the top of the carb and mess up the jetting in that cylinder.
 
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Discussion starter · #36 ·
utp216 said:
Did you happen to take the tops off the carbs to clean them, etc? There is a tiny o-ring under the cap that fits in the top of the carb body to seal the vacuum port. If that o-ring is missing you will pull air at the top of the carb and mess up the jetting in that cylinder.
Click to expand...
Nope never touched my carbs....had a local shop tune them last year, ran fine all year til last month!
 
#37 ·
On the #3 intake boot there is a brass fitting that has a rubber vacuum line that should lead to your fuel valve (unless you have replaced it with a Pingel fuel valve). The vacuum line connects to another fitting that is between the two fuel outlets in the fuel valve. The way the valve works is when the motor is running and pulling vacuum fuel valve it pulls a diaphragm back and lets the fuel flow to the outlets.

If there is a leak somewhere in that vacuum circuit it will throw the jetting off in that carb.
 
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#38 ·
Also make sure that all four of the plastic caps on the top of the carbs have there vacuum fitting intact. I have seen one of those little pieces of plastic break off before.

Check to make sure that all four of them have those little rubber covers on them to seal them.
 
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#39 ·
utp216 said:
On the #3 intake boot there is a brass fitting that has a rubber vacuum line that should lead to your fuel valve (unless you have replaced it with a Pingel fuel valve). The vacuum line connects to another fitting that is between the two fuel outlets in the fuel valve. The way the valve works is when the motor is running and pulling vacuum fuel valve it pulls a diaphragm back and lets the fuel flow to the outlets.

If there is a leak somewhere in that vacuum circuit it will throw the jetting off in that carb.
Click to expand...
While you're at it, check that fuel vacuum line for a good seal at either end and any cracks or splits!

I wouldn't discount a crappy lead going to your no. 3 plug or even a buggered up plug cap! Did you ever try swapping leads from 2 and 3 to see if the problem moves??
 
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#40 ·
His problem is so wierd in the fact that he has good compression and his plugs look good except for that one cylinder. Strange indeed.

Get moving on swapping the #2 and #3 spark plug cap over and see if #2 starts acting up. At least then you can figure it is either the coil or the plug wire/cap.
 
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RoamingBison
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