Not Firing on Two Cylinders.

I started her up the other day it seemed to be running a little rough. I felt the headers and noticed No. 1 was cool, while the others were getting hot. Shut it down and left it be as I didn't have the time at the moment to look into it much further. Last night I started it up again and this time Cylinders 1 & 4 were both cool. I suspect a coil or some disconnected or bad connections in the wiring.

Plugs and wires were both replaced last fall and the bike only has about 45 minutes idling time since then as I have been working on all of the other mechanicals (brakes, tires, levers, etc.). Until this most recent incident, everything seemed to be running smooth.

Suggestions before I begin to sort this out later this week as I get time?

I was encouraged as I was getting so close to having everything else ready to ride; then this.

Of note: I am fairly inexperienced with electrical system diagnosis. I have a multi-meter and am familiar with basic functions. My point is, specifics are appreciated.

 

1 and 4 are off of the same coil pack
could be the pick up coils have failed ohm them out you do this at the tci
orange wire to black gray wire to same black


how did you replace the spark plug wires?

45 min of ideling could have fouled the plugs clean them

ohm out ignition system
Pick-up coils:
650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range


Ignition Coils:

Primary side (input from main wiring harness):
2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range


Spark plug caps:
1981-83 models: 5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range
1984 RL models: 10K +/- 20% = 8,000 to 12,000 ohms per cap acceptable range

Spark plugs:
0 ohms per plug

spark plug caps unscrew by the way.

 

How to Use a Multimeter and Read Schematics and Wiring Diagrams.



then you want to suspect fuel flow have you cleaned the carbs?

 

The interim PO claimed to have cleaned them and there is evidence he had. This was a non-running bike that had sat for many years prior to the PO. He got it running, cleaned carbs, repaired intake boots, replaced petcock & fuel line, replaced plugs and wires and a few other things before I acquired it. The 45 min idling time is accumulative over the winter season in small increments of approximately 5-8 min.

I will hopefully have a chance for closer inspection this eve.

 

Rule #1: don't believe ANYTHING the PO tells you that he did.

Rule #2: even if you do believe (or find evidence thereof) that the PO actually DID do what he claimed to have done, don't believe for a moment that whatever was done, was done correctly (this includes any service done by a shop)

Rule #3: refer to Rule 1 and 2..........

 

Had a brief few minutes to take a look. Pulled a couple plugs; they are wet and black and smell like fuel. Wiped them off a bit and put them back in. Started bike up and got fire in cylnders 1-3; still not 4. I now think it is fouling causing the issue. Probably from those cold starts running the bike for a few minutes over the winter with the choke on all of the time.

 

starter fluid can do that , did you use it?

 

Nope, never. Possibly the PO?

 

This is what the plugs looked like:


Pulled all of the plugs and cleaned up with some emory cloth and a brass brush to remove the carbon.

After re-installation, all four cylinders fire. Need to determine the cause of the fouled plugs.

 

electric spray cleaner works too

 

Soooo true