rpm stumble, miss

[Ron Moss]

Hey guys and gals, I have a question that so far has me stumped. I'm semi-retired have been riding and working on bikes for 40+ years. My query is, my xs1100 special started mising at high rpm's (5000+) then missing at lower and lower rpm's. When I got home I checked to see if I had good spark and it was very weak. So first thought was the coils are bad. (same results on each coil) I work part time at a small motorcycle shop. We have a coil tester so we tested the coils and they checked good and strong. I am in the process of checking all electrical connections and everything else I can think of. Has enyone else had something like this happen?? Any help welcome.

[John]

Sounds like the infamous pick up coil wire problem. There are only two types of XS riders: Those who have had broken pick up coil wires, and those who will. Welcome to the club Ron. There are repair tips in the maintence section here. Grab a beer, and read up. You'll be able to fix it once you find it.

[Ron Moss]

I will be checking the pick up coil wires this afternoon after work but if the wires are broken wouldn't you get no spark not a weak spark like I'm getting.

[TopCatGr58]

Ron,

The wires are braided, and fracture from flexing over time, but the insulator keeps them in some contact, and depending on the amount of flex, due to centrifugal and vacuum advance movement of the timing plate, the wires will have more or less of the number of strands still barely making contact, or intermittent contact, providing less than the optimal signal or time of the signal sent to the TCI, so it energizes the coils for less time than needed to develop a strong spark!?
T.C.

[Ron Moss]

I did as you all said. I checked the coil pickup wires and could not find a break even with tuging on them. I cut into each wire and exposed the braided wire so I could get a good grip to pull on it.
Still could not find a break. I put in a small section of wire to make each one a little longer, soldered every together, heat shrinked everything and now it runs like the striped ape we all hear about.
I suppose this a tempory fix but it works for now.

[Ken Talbot]

I've been fighting this same thing on SWMBO's H for a while now, and with this season's start-up, it finally came to a head. I know what to look for, and I looked and tugged and I still couldn't find the break. Then, I noticed that the bundle of four wires, now inside a braided sheath, is held in a pinch-type clamp just before it exits the casing. Just looking at it, it seemed the crimp was awfully tight for what it needed to do. Sure enough, when I removed the crimp and opened up it up, there was the break in one of the wires. A quick clean-up, a dab of solder, a bit of heat-shrink, and the problem is gone. If you never dir find your break, maybe you also need to look a little farther along the wires.
JAT....

[Ron Moss]

Thanks for the reply Ken, I thought when I get time I would go over everything again and maybe replace more of the wiring and look a little closer.

[Redbaron]

Pick up wire fix

The hourglass method will work, however I have found it easier to check continuity with an Ohm Meter. Ohm meter- $10.00, knowing I have done it right-priceless. (Please Forgive the shamless theft of the "priceless" thing. Couldn't help it.)