3 cylinders?

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AlaskaWing

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I changed my plugs today and when done, started the bike and it sounded pretty normal. I then , on a whim, unplugged a sparkplug cable, left rear, and there was absolutely no change.. all of the other cables when unplugged had an instant effect....

What's up with that?

It seems to run fine on just the 3 cylinders....sigh....
 
Might be the resistor in the plug cap is corroded or gone. Or possibly a bad wire. Yes they do run very well on 3 cylinders.
 
Soooo....

Could I test it by moving a wire from 1 plug to another?

I mean completely change out the wire on the bad plug. And see if the bad plug changes to another cylinder?
 
Before you change the wire, I would pull the plug on the dead cylinder and see if you have spark there. No spark, try a different plug. Sometimes you can get a bad plug from the factory.

If you change the wire and still no spark, your problem could be a deteriorated coil or pulse generator.

You have probably done this already, but I would check each connection from the pulse generators , Ignition Control Module, coils, and use di-electric grease on each connection. It helps prevent corrosion and keeps water out.
 
Lots of spark...was jumping a full inch! Scared the crap out of me!!!

I also tried moving the plugs around to see if maybe I had a bad plug with spark...same cylinder not firing.



So ... what else ?
 
Carburetor not getting gas? Or possibly slow jet plugged. Try a few love taps with a screwdriver handle to that carb.
 
If you have spark at the plug, the problem is either lack of fuel or low compression.

Check the compression. Anything below 100 could cause a dead cylinder.

Check the plug to see if it smells of gasoline or is wet. If no sign of fuel, find the drain plug on that carburetor and see if there is fuel in the bowl. If fuel in bowl, start thinking about the idle jet. If no fuel in bowl, the float valve could be stuck or plugged. Tap on the carburetor as said earlier.
 
Ok.

Wasn't sure how to test compression beyond sticking my finger in the spark plug hole, and comparing it to the pressure of the cylinder in front of it. They seemed about equal.

I found the drain valve for the carburetor and loosened it enough to see a little gas drip out. So there seems to be fuel in the bowl.

Ran the engine at 5,000rpm and pulled the plug wire, no change, but definite change if I pull a different wire.

What's a idle jet?
 
Is the exhaust header on that cylinder hot when it’s running ? If you remove the spark plug on that cylinder and crank the engine does a mist of gas shoot out the spark plug hole ?
 
You said you have spark at the spark plug and there is gas in the carburetor, so the remaining causes for a dead cylinder are narrowed down to gas not getting into the cylinder or low compression.

Remove the offending spark plug, ground that plug wire, hold a white paper towel in the spark plug hole and see if gasoline gets on the paper when you start and run the engine. If you don't get gas on the towel, dump 4 ounces of ATF in the gas tank and top off the tank with gas. The ATF will help clean the jets in the carburetor and may clear up the problem. If no improvement after 100 miles, pull the carburetors and clean them. There are several threads in here on how to clean the carburetors and what to look for.

If you get gas on the towel, you are down to low compression as the culprit. You can order a compression gauge from Walmart online for around $20, probably higher in Alaska. If you don't want to buy a compression gauge, see if AutoZone or O’Reillys will lend you one; they do down here. The finger test says you have compression, but not how much, the gauge will tell you how much. All cylinders should register within 10-15% of each other and all should be over 100psi.
 
[url=https://www.classicgoldwings.com/forum/viewtopic.php?p=204192#p204192:2y49b7sr said:
PurpleGL1200I » Mon Jul 02, 2018 8:31 pm[/url]":2y49b7sr]
Remove the offending spark plug, ground that plug wire, hold a white paper towel in the spark plug hole and see if gasoline gets on the paper when you start and run the engine.....

Why am I grounding the plug wire while I run the engine? Just curious.
 
[url=https://www.classicgoldwings.com/forum/viewtopic.php?p=204209#p204209:5vo8gzca said:
AlaskaWing » Tue Jul 03, 2018 5:15 pm[/url]":5vo8gzca]
Soooo....I guess holding the plug against the manifold wouldn't be grounding it! Good thing I asked.
That would be grounding the plug and checking it for spark.
 
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