Chasing a bad miss

[copracr]

I think I have an ignition problem on cyls 2 and 3 so I started using this guide to track it down:
http://www.xs11.com/forum/showthread.php?t=583
I'm getting 3.7ohms at the ignition box across the primary side of both coils, 1.7 ohms at the coils. On the secondary side I'm getting 0.9-1.1 Mohms on the 1+4 coil (which runs fine) and 14 Mohms on the 2+3 coil. What does that mean???

I've already checked the pickup side of the ignition and it was in spec. My issue is a bad miss at all rpms and cyls 2+3 are black plugs.

[Courtney]

I would check your ignition coils. One coil fires 1 & 4, and the other fires 2 & 3. Trace the sparkplug wires back from 2&3 and see which coil they go to. Check it for good. I suspect that is where your trouble lies, or something in that circuit.

[copracr]

Yea, I'm thinking the 1+4 coil is out of spec but runs fine and the 2+3 coil is in spec but doesn't.

[crazy steve]

The stock '78-80 coils should check as follows: 1.5 ohms across the primary side, and 15K ohms across the secondary side with the spark plug ends removed from the wires (they unscrew). Each plug end should read 5K ohms through it. You can go plus or minus 10% and still be safe. The plug ends are a pretty common failure point and replaceable. You'll also run into poor connections where they're screwed on, sometimes trimming 1/4" off the end of the wires will fix that.

[BA80]

Check the pickup coil wires. Have you ohmed out the pickups while moving the wires around under the ignition cover?

Sounds like a classic picup coil problem.

[CaptonZap]

http://www.xs11.com/forum/showthread.php?t=583
. On the secondary side I'm getting 0.9-1.1 Mohms on the 1+4 coil (which runs fine) and 14 Mohms on the 2+3 coil. What does that mean???

.

If your meter has a K (kilo) ohm range, try it and let us know what the coils read. Try 20 K range.
If, as you state, the reading is in the M (mega) ohm range, it means that the secondary winding is compromised (screwed up). Open windings will read Mohm values due to slight continuity through the insulation/moisture/ your fingers on both probes/etc.
CZ

[Petersg_99]

When I read the title of this thread: Chasing a bad "Miss"

I caught myself thinking: Is she wearing black Leather?

[hamjam]

caution, chasing a bad miss may lead to divorce

[Shacknasty]

caution, chasing a bad miss may lead to divorce

Or a restraining order!

[copracr]

It's been a while since I tried to get this bike going but other projects are done and I'm back to getting my bike going.
So here's an update:
I did all the stuff you guys suggested and everything checked out. I even swapped out the 2+3 coil just to be sure. I then bought some of those inline spark testers with bulbs in them. All four coils fire just about even.
So I moved on to the carbs. I pulled all four and first thing I did was drain them individually into a jar. Number 2 had about 1 and a quarter more fuel than the other 3. I pulled the plugs out again to double check them and number 2 is covered in carbon and number 3 looks just a little rich (1 and 4 looked about right with some tan).

I thought maybe the inlet needle valve was sticking open or the float level was wrong. I can't blow through the fuel inlet while the carbs are upside down and the float looks level with the other 3. Is there something else I could look at?

And the weird thing is this whole problem was a sudden onset. If the float level was wrong it should have ran poor all along, but it didn't.

[jjz28]

maybe that float has a small hole and is getting gas in it so it wont float. One of my floats was like that so I had to get another one.

[DGXSER]

Are they stock coils? Also, try, if they reach, to swap out the coils. Move the 2-3 wires to plugs 1 and 4 and vice versa, then switch the grey wire with the orange wire at the low side of the coils to keep your timing correct.

If you do this and the miss moves to 1 and 4, then you know you have either a coil or pick-up coil problem.

[copracr]

Are they stock coils? Also, try, if they reach, to swap out the coils. Move the 2-3 wires to plugs 1 and 4 and vice versa, then switch the grey wire with the orange wire at the low side of the coils to keep your timing correct.

If you do this and the miss moves to 1 and 4, then you know you have either a coil or pick-up coil problem.

I can't get the 2/3 coil to reach plug 1. But I already swapped that coil out entirely with no change.

I also broke out my micrometer and set the bowls exactly at 25mm. 2 was at about 19 and 3 was about 21. No change to running and when I drained the carbs there was about equal fuel in the bowls this time.

Basically at this point, plug 2 is black, the others are OK, and it won't start or idle without the choke on.

[bikerphil]

it won't start or idle without the choke on.

Pilot circuits are plugged.

[DGXSER]

Also, unless you mistyped, your fuel levels are wrong. You want 23 mm not 25 mm.