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Cyl. 3-4 misfiring

  • Thread starter Thread starter jacora
  • Start date Start date
J

jacora

Guest
Guys; This is a great place of information, thanks for it.
Problem: Weak spark at cylinders 3 and 4, later plugs got fouled and lot of problems after that.

My bike is a GS1100E 1983, just headers and carb jetting.

I just replaced the coils with dynatek units to make cylinders 3 and 4 fires correctly, but they don't. I check the signal generator impedance and its ok. As per Haynes manual and doing the ignitor test the plugs 3 and 4 should produce spark as you touch the specified contacts and they don't.
Question: Which is better, replace with the original or install a Dyna 2000 system? Do I have to hurt my wire harness?
Which is your opinion about the source of the problem?
All inputs will be appreciated
 
OK, originally I understood you to be saying you had spark on the 1,2 plugs and no spark on the 3,4 plugs. Now, I understand you have good spark on the 1,2 plugs and weak spark on the 3,4 plugs. If you have good spark on the 1,2 plugs, then both sides of the ignitor are working, both crank triggers are working and both coils are working. So, the problem has to be the spark plug wires, the spark plugs, or the plug caps on the 3 and 4 cylinders. I would remove the resistor spark plug caps (unscrew them from the wire end) and trim about 1/4" from the ends of the wires, then screw them tightly back on and install new spark plugs. (you said you plugs were fouled) It could be nothing more than a poor connection between plug wire and cap on both cylinders. Also, take a multimeter and set it to ohms.
While you have a cap off, the resistance through a good plug cap should be 5K (5000) ohms. If you're anywhere near that range, the plug cap should be OK. If not, I would replace them.

Earl



jacora said:
Guys; This is a great place of information, thanks for it.
Problem: Weak spark at cylinders 3 and 4, later plugs got fouled and lot of problems after that.

My bike is a GS1100E 1983, just headers and carb jetting.

I just replaced the coils with dynatek units to make cylinders 3 and 4 fires correctly, but they don't. I check the signal generator impedance and its ok. As per Haynes manual and doing the ignitor test the plugs 3 and 4 should produce spark as you touch the specified contacts and they don't.
Question: Which is better, replace with the original or install a Dyna 2000 system? Do I have to hurt my wire harness?
Which is your opinion about the source of the problem?
All inputs will be appreciated
Click to expand...
 
The problem is that I had a weak spark at 3, 4 plugs that make them got fouled on about +/-50 to 75 miles of being running. If I make a plugs change just on those two cylinders the bike runs normal again up to next 50 to 75 miles.
The coils and cable complete set up were changed and the problem still there the same than before coils and cable change, the coils are NEW Dynatek green ones (3 ohm) and cables are also NEW Dynatek copper solid core along with their corresponding caps and boots.
  1. Can you or anybody else explain me how the igniter works?
  2. Also, talking about the ignition system, Which component of such system has #3 and #4 cylinders in common?
So, one of the crank triggers controls coil for 1, 4 cylinders and the other one have control over the coil for 2, 3.
Ok if I am correct and if I have a strong spark at 1 and 2 cylinders that means as you said both coils, igniter and triggers are working fine. I really can't understand were the problem is.

Earl, Thanks for your help, Keep coming, All the inputs are appreciated.

jacora
 
OK, you have new dyna coils, new plug boots and new wires. I think we can assume there is nothing wrong with those parts.

You said,........... "So, one of the crank triggers controls coil for 1, 4 cylinders and the other one have control over the coil for 2, 3.
Ok if I am correct and if I have a strong spark at 1 and 2 cylinders that means as you said both coils, igniter and triggers are working fine."
********You are correct on this.

OK, now you said if you put new spark plugs on the 3, and 4 cylinders, the bike will run fine for 50 to 75 miles. AaaaHaaa.......if the ignition was not working, installing new spark plugs would not change anything. You have a fuel problem. You're fouling spark plugs, so its not an induction air leak because that would cause a lean condition, not the rich condition you have.
The problem is the #3 and #4 carburetors. I would remove the carb rack and check the float level settings to be sure the fuel levels are not too high.
If you have not already cleaned and replaced the "o" rings in the carbs, I would do it at this time since you already will have the carbs removed. Over time, those "O" rings dry out and no longer seal properly. Particularly the ones on the fuel inlet needles which when they leak let an endless flow of fuel into the float bowls resulting in the carb running too rich. After that, on reinstallation of the carbs on the bike, make sure the choke cable has some slack in it so the choke is actually off when it is in the off position.
At that point, do a vacuum synch on the carbs. Badly mismatched vaccum between carbs changes fuel induction drastically and a very rich mixture fouls plugs and causes what appears to be a weak ignition spark. The problem is not that the ignition spark is weak, its that the plugs are grounding out from being too wet with fuel.

The #3 and #4 cylinders are not in common at any point in the ignition system.

Robert Barr sells carburetor "O" ring kits for your bike and they are not expensive. Money well spent.
I havent bought a kit from him in some months now, but I if I remember, his site is http://www.cycleorings.com/
The kit was about $15 (the kit replaces all the "o" rings in all four carbs)

Earl






jacora said:
The problem is that I had a weak spark at 3, 4 plugs that make them got fouled on about +/-50 to 75 miles of being running. If I make a plugs change just on those two cylinders the bike runs normal again up to next 50 to 75 miles.
The coils and cable complete set up were changed and the problem still there the same than before coils and cable change, the coils are NEW Dynatek green ones (3 ohm) and cables are also NEW Dynatek copper solid core along with their corresponding caps and boots.
  1. Can you or anybody else explain me how the igniter works?
  2. Also, talking about the ignition system, Which component of such system has #3 and #4 cylinders in common?
So, one of the crank triggers controls coil for 1, 4 cylinders and the other one have control over the coil for 2, 3.
Ok if I am correct and if I have a strong spark at 1 and 2 cylinders that means as you said both coils, igniter and triggers are working fine. I really can't understand were the problem is.

Earl, Thanks for your help, Keep coming, All the inputs are appreciated.

jacora
Click to expand...
 
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High rpm's idle problem

High rpm's idle problem

Ok, I already did the O-rings change and use the opportunity to perform a complete cleaning of everything inside the carburetors, I found some dirt. Then at the time to turn on the bike it idles (if you can call it that way?) at 5,000 rpm's. Wow, what a problem. I turned in the idle screw and just get to slow the rpm's to 3,000. I check the intake boots, the intake boots clamps and everything looks like new, the butterflies are totally closed. When I was cleaning I didn't mess with them. This morning I took a look to inside of them and saw that the carbs were wet with a little gas deposit just in back side of butterflies. I believe that the gas comes from the needle jet. Before all this cleaning procedure the bike was idling acceptable (not perfect) but the mixture were extremely rich to the 3 and 4 cylinders. :cry: HELP ME!!!!!!
 
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