Only 2

[OneHand]

I should be sharing my description with Hobbyman... I feel like a complete idiot (That's not the first time, and won't be the last!)
"XSively Complete Idiot" ???

Just to check what the carbs are doing, I pulled the plugs last night. DANG!!! Looks like 2 &3 are not firing. 1&4 seem fine, maybe even slightly lean (as expected)

Now, if this bike runs the way it does on 2 cylinders, I can't wait to feel what all 4 feels like!!!!!

Plan of action for now: Check and re-check pick-up fix that I did a while ago. I checked that no. 2 spark while idling, but must be losing spark when the revs pick up, or gone completely bang since then

Check coils and TCI. Replace spark plug caps and wires (Should have done this a long time ago!).

Throw match in gas tank if it still does not run properly...!

L8er
1H

[HobbyMan]

I knew more people felt like that except myself You know, when I first got my Dad's XS running before I got my MC license, It was only running on 2 cylinders. It was plugged up and the old fuel lines were kinking. One week I started running a bunch of MMO and carb cleaner through the gas. Keep in mind that I didn't even know how to thoroughly clean the carbs then. Anyway, one day I was just putting around the neighborhood when WHAMMMOO!!!!, all 4 started firing properly. I almost fell off the bike. What a feeling! Since that moment, I knew I was hooked.

[Kurt]

Send me your left side cover before you throw any matches

[OneHand]

Sorry Kurt...

Still looking for sidecovers (both) myself...

Have basically come to the point where I'll be making some sort of side-covers out of SS sheetmetal myself. Don't know how yet, but will get over that bridge when I get there.

Back to the problem: Pulled the whole ignition system apart last night to check the obvious causes.

Pick-ups are fine, TCI, as far as I can see is fine. Coils check out.
I do have spark on all 4 if I turn the motor over.
The only variable I could find is the spark plug caps...

1 and 4 are the the small 90 deg ones with 5k Ohm resistance. 2 and 3 are longer plugs which don't seem to have any resistance.

Question: Would the non-resistor plug caps cause it to lose spark, produce a weak spark, fry plugs, not running right?????

I'll go get some new caps tommorow, but will have to wait for a week or two now to get Vader back together. I started pulling the body work apart for painting. The tank is off and stripped of cap, petcocks etc. Seat is off to be re-covered by SWMBO. Got some nice vinyl for under $10.

1H

[skids]

There is a thread in this forum somewhere about that resistor that goes bad in the plug connectors (caps). The connectors can start misfiring when they get hot and so can the coils. Test when hot. Test right through connectors by pulling the caps off of the plugs (1 & 4, then 2 & 3) and test Kohms resistance thriugh the pairs. Check the manual, but I am thinking the coil and wires should be 15Kohms, add rated Kohms for each cap, ie 5Kohms each, and check for total rated ohms. In this example, it would be 25 kohms +/- 10 %. If there is anything wrong you should know it right away.

It isn't likely that all would go bad at once... Also, if you get the longer stem variety, what are they, 120 degree bend(?), you can cary one in your tool bag in case any of the bike's go bad. It looks kind of funny on the outside cylinder but it will get you home and will conserve space in your tool bag. Me, I would replace all 4 if there was any doubt. Sometimes, there is corrosion at the stranded plug wire/plug connector contact. If that is the case, and yours are long enough to trim about a cm off of the ends, try that.

About the kohms rating per cap, I don't think that matters much whether they are 8 kohms or 3k ohms, but it might be a good idea to match the plug caps on pairs. It is the same for plugs...resistor vs nonresistor. If you are using radios, it might be important to use resistor type however.

[OneHand]

Thx skids

I get 15K ohm between the pairs, with the caps off. Did not even think to measure it with the caps on. Anyway, will be getting 4 new caps this afternoon, but won't be able to check till the paint job is done. Might even see if I can't find a spare coil from the breakers at the same time to just make double sure.

Hav never tested it when hot. The fiddling allways seem to start late at night after a little bulb goes on. Soon to be shattered when I find something else that has gone wrong...

1H