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Confusing spark problem.

  • Thread starter Thread starter ThomasTedder
  • Start date Start date
T

ThomasTedder

Guest
Well, I finally got the bike ready put back together, but I have a weird problem.

First off, #1 wasn't firing, but 2, 3, & 4 were. The plug was wet with gas. I checked for spark and it was there. I left for a while.

When I came back, #2,3 where the only ones firing. I swapped coils and now #1,4 were firing, but not 2,3. I swapped back and 2,3 were once again firing, but not 1,4. So, I figured I had a bad coil.

This is where I get confused. I decided to check the plug wire boots. The wires were fairly corroded where the boot connects. I cleaned them up and put them back on. 1,4 now fires. BUT for some strange reason 2,3 are not firing anymore. They were firing fine until I cleaned I cleaned 1,4.

2,3 still has spark. Nice big blue spark. I can unplug 2,3 and the bike still runs on 1,4, but not vice versa.

Also, I am getting random backfires.

The coils and everything are normalized. I am 100% percent positive. I never unbolted the coils just swapped wires. I know it is properly normalized because the wires have to stretch to reach the other coil when swapped. The plug wires are numbered, so they aren't mixed up either.

My problem moved coils, and I don't know why. If this is confusing let me know and I will try to reword it.
 
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I would start checking the wiring that feed the coils. Have you gone through the harness and cleaned the connectors that feed the coils, the ignitor and the pickups. Your bike has been sitting for a while, I would change the plug wires or trim the ends and reinstall the caps.
 
I forgot to mention that in the course of troubleshooting earlier, I swapped the inside plugs with the outside ones. I just thought of this so I went to the parts store and bought four new D8EA plugs and what do you know? The problem reversed itself again. ARRGGHHH.

1,4 were firing 2,3 weren't. I put in new plugs. Nothing else. Now 2,3 are firing and 1,4 aren't. 1,4 still have spark, but aren't firing. What the hell could cause this?
 
almarconi said:
So whats the problem?
Click to expand...

That is the problem. Only 2,3 are firing. When the bike is running 1,4 pipes are stone cold. 2,3 pipes are scalding hot. I pull the #1 plug when the bike is still running and it's sparking good. Put the boot back on and the pipe is still cold. I kill the motor and check the plug and it's wet with gas. A little while ago, before I changed the plugs, the exact same thing was happening except on the opposite cylinders. I know I'm not crazy.
 
Well if you have spark, then you need compression and fuel in the proper amounts and at the right time for the cylinder to fire.

Did you check the compression in the cylinders?
If you have compression then do you have fuel going to the cylinder?
Is the plug for #1 and #4 wet?
Is there fuel in the #1 and #4 bowls?
Have you checked the valves yet?
Have you verified the engine timing yet?

I know you want to get the bike running but you need to check the basics first.
 
almarconi said:
Well if you have spark, then you need compression and fuel in the proper amounts and at the right time for the cylinder to fire.

Did you check the compression in the cylinders?
If you have compression then do you have fuel going to the cylinder?
Is the plug for #1 and #4 wet?
Is there fuel in the #1 and #4 bowls?
Have you checked the valves yet?
Have you verified the engine timing yet?

I know you want to get the bike running but you need to check the basics first.
Click to expand...

There is fuel to all cylinders. The plugs that don't fire do get wet.

I have not checked the valves, timing or compression. But if the bike will run on two cylinders, then stop running on those two and start running on the other two, my problem lies elsewhere. I'll get to these in due time.

The obvious solution would seem to be wiring, but why would it switch cylinders after a spark plug change? Compression doesn't magically switch back and forth between 1,3 and 2,4. Neither does timing or valves. Wiring might, but I still have spark. I have spark, compression, gas, and air. I can think of two things. Either the timing is off (not likely) or maybe somthing hokey with the ignition system. Is there anyway that there is spark on a wire, but when it is hooked up to a plug, the load causes it to stop sparking? I only checked the coils earlier by swapping them. It's dark now, but tomorrow I'll give them a check with the multimeter.
 
Is there anyway that there is spark on a wire, but when it is hooked up to a plug, the load causes it to stop sparking?
Click to expand...

A faulty resistor cap could cause this problem. Remove the cap and check the resistance with your multimeter. Should read about 5k ohms. Does your bike have resistor caps, they are screwed onto the end of the plug wires?

I can sense your frustration but no one on this forum can help you because we have know way of knowing what has been done or not been done to your bike in the past. When your bike was sitting in the alley mice could have been building a nest inside your ignition cover for all we know. When restoring a bike that has been sitting you really don't know what you are going to get into. You may very well have electrical problems but until you go through the harness there is no way of telling. I know on my bike I had to start in the headlight bucket and end at the taillight cleaning every connector. There are no maintenance records or previous owners to consult with on these abandoned and neglected bikes.
 
almarconi said:
A faulty resistor cap could cause this problem. Remove the cap and check the resistance with your multimeter. Should read about 5k ohms. Does your bike have resistor caps, they are screwed onto the end of the plug wires?

I can sense your frustration but no one on this forum can help you because we have know way of knowing what has been done or not been done to your bike in the past. When your bike was sitting in the alley mice could have been building a nest inside your ignition cover for all we know. When restoring a bike that has been sitting you really don't know what you are going to get into. You may very well have electrical problems but until you go through the harness there is no way of telling. I know on my bike I had to start in the headlight bucket and end at the taillight cleaning every connector. There are no maintenance records or previous owners to consult with on these abandoned and neglected bikes.
Click to expand...

I do have resistor caps. I'll check the resistance of those tomorrow too. Thanks for the help Almarconi.
 
tkent02 said:
Dark is the best light for checking spark plug wires, you may find sparks flying in all the wrong places that can't be seen in daylight.
Click to expand...

I did check that when it was getting dusk. Didn't see anything jumping through. I couldn't wait until full dark, though. My next door neighbors are older than dirt with the associated health problems. They go to bed when the sun does.
 
hi,are your plugs new?Just because they spark when removed doesnt mean they will spark under pressure and you should check your plug caps for cracks.Do your pipes heat up if you open the throttle?Are your carbs ballanced?
 
greg becker said:
hi,are your plugs new?Just because they spark when removed doesnt mean they will spark under pressure and you should check your plug caps for cracks.Do your pipes heat up if you open the throttle?Are your carbs ballanced?
Click to expand...

Plugs are new. Pipes stay cold in all throttle positions. Carb are good.
 
Solved

Solved

I caught a break this morning. When I fired it up, it was still only running on two cylinders, but with a catch. 2,4 were firing and not 1,3, eliminating the coils. I wiggled the spark plug boots and all four started firing. It's one heck of a coincidence that they were coming on and off in pairs. When I would pull them off to check for spark, they would get a good connection. When I would put them back on, they would lose connection. Sooooo

I went for a ride around the block. Bike runs pretty good for a 650. I'm grinning ear-to-ear when I get back home. I got off and saw smoke coming from under the tank. The gas found an exit out of the rusty tank. At least it runs.
 
mine started to do that also. i can get it to run, ran it for about 20minutes 2-3 cold as could be. come back aa couple hours later 1-4 cold as could be.. i think its something to do with the spark of the points, cause sometimes i can see both sets sparking then neithr one spark then just one will spark.:-k perhaps condensors? points ? coil wires ? plugs ?
with my luck its something else...
 
Start with the basics. The coil wires usually have a number indicating the cylinder they go to somewhere on the spark plug wire lead. As long as you did not change the 1/4" spade terminal connections these numbers should still be valid.

Check the gap on each plug and clean oil off any plug. Insert carefully and torque to 11 ft/lbs of torque. Over tightening the plugs can ruin your day.

Now inspect the spark plug boots and if they are cracked or damaged replace them. NGK boots are only 4 dollars each at the stealer dealer so it's a small price to pay for good spark.

If you do replace the boots cut about 1/2 inch off the end to get to new wire inside.

Then try it again.
 
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