It was easy enough to figure out that the other two cylinders had no spark by pulling one of the plug wires. I knew from changing plugs that it has a dual system with two coils and two ignitors, two cylinders on each. It wasn't likely plugs, since they were new. Fortunately, since it was running on two cylinders, it was also easy to figure out where the problem was by switching the coil and ignitor connections. The coils made no difference, but switching the ignitor leads also switched the running cylinders. (The ignitors were actually off a 750 Magna, also a good thing in a way, because the Magna ignitors are made with a printed board in an open plastic case. Some OEM ignitors are in an aluminum case filled with cast resin, which makes the inside pretty hard to do anything with.)
When I looked at the ignitors in the bike, I realized they were only really connected by three wires (five connections, but two branched off the same leads), which I figured were probably power, circuit, and ground. The general idea of electronic controls is to manage engine operation by changing timing and spark settings, so it occurred to me to wonder if most of the ignitor insides were really absolutely essential to run the engine. If I could by-pass the non-functioning parts of the ignitor, would it run, just not as well?I had to either jump the wire connections directly, which seemed like asking for a dead short in the system, or try to connect the terminals in the ignitor that matched the wiring. The biggest risk from the terminals in the ignitor would be to the ignitor itself, which was already dysfunctional anyway, so I wouldn't be any worse off.
I pried the plastic case apart with my pocket knife and got the circuit board out where I could set the jaws of needle-nose pliers on the connections. I looked for power-in and the primary circuit connection, which I have no idea if I found, but on the second try there was a spark and I'll be damned if the other two cylinders didn't kick in. It ran perfectly all the way home, where I parked it until I got a set of OEM ignitors online from Zanotti in PA. After that I ran it for about six more months with the new ignitors in my pocket before I finally got around to actually installing them.
I cannot provide a plausible scientific or technical explanation for this phenomenon. Did I succeed in bypassing the main components of the ignitor, or did I simply manage to juke an obstinate resistor or bad connection into operation? I have no idea.
The displaced Magna ignitors lived in a box somewhere for a couple of years after I moved on to an 84 VF1100S Sabre, with a likewise dysfunctional odometer and likewise gawd knows how many miles. This time I didn't get stuck at work, but one day when I came out to start the bike in the morning after it had been sitting awhile, same routine. For no apparent reason, two cylinders gone. Moisture? Temperature? Corrosion? I'd like to know how these things go from working fine to dead the next time without anything in between. At least with mechanical points and voltage regulators you usually got some warning.
The VF1100 Sabre (VF110S) V-four has the same engine as the VF1100 Magna (VF1100C), referred to in cubic inches as the V65, manufactured mostly between 1983 and 1986, also closely related to the 750 Sabres and Magnas. The systems on the Sabre/Magna 700s and 500s seem to be different from the 1100s and 750s, although the electrical connections on the ignitors are the same for all of them and for the CBs as well. The ignitors for the 1100s and 750s are very similar, and I tried the same routine with the connections, but my luck didn't hold up this time, so I dragged out the old 750 ignitors from the CB. The same one I operated on in the business parking lot worked perfectly while I looked for an 1100 replacement on ebay.
There are still new ones around for a hundred and fifty or so, but I'm reluctant to put much money into a bike with a doubtful life expectancy, so I was looking for something used, more in the neighborhood of twenty-five. Generally they run fifty to a hundred, but twenty-five is doable if you stay on it for a few days. Some people sell low and move stuff quick instead of holding out for a higher price, but you have to track them and be ready to buy.
Sometimes you can also get a pair for fifty to a hundred, although they are generally higher. It may pay to search under igniter, ECU, spark box, and black box, as well as ignitor, for the VF1100, VF1100S and VF1100C, Sabre, Magna, VF750, V65, and V45. V40 is the VF700. I have seen usable ignitors listed under all of those and even some combinations. Searching for Sabre VF1100S ignitor may get different results than Sabre VF1100 ignitor, for instance, and spacing, such as “VF 1100 S” instead of “VF1100S” can turn up something else, although it shouldn't. “Sabre” can also be listed as “Saber,” and some of the people listing used parts on ebay have their own ideas about spelling, such as “Mangna.” (A cartoon motorcycle?)
In the VF1100S the two ignitors are identical except that the one in the bigger box has the rev limiter circuit in it. The bikes run just as well on two of the smaller ones as they do on one of each, maybe better, and the smaller ones are generally cheaper. If I had a new Hayabusa with nitro or a Harley glider, I might worry about over-rev, but on a twenty-five year old bike with more miles than a moon-lander, I would consider it an honor to blow out an engine at fourteen or fifteen thousand RPM, which may not be such a stretch of the imagination.
I have buried the tachometer in fourth gear, but not in fifth or sixth, although I'm tempted. The bike red lines at ten, and theoretically 12K, the top of the red zone, would be about 175 MPH in sixth. 3K beyond red would add another 15 MPH, but on the other hand, would I want to risk throwing a rod at upwards of 200 MPH and 15K RPM on a rolling dinosaur? Maybe not. The practical potential for 190 MPH on an old 1100 is probably sheer fantasy anyway. I've never seen an actual test speed much over 150 for these bikes, although that was for a quarter mile, not an all-out,
top-end assault. Dream on.
Back to the reality side of ignitors, there are a few more items that might be useful to somebody with these problems. I bought a cheap used ignitor for a VF500 as a temporary replacement ($12 plus $5 shipping), mostly just to see if it would work in the VF1100, which it does, but not very well. I have no way to test the unit otherwise, so I don't know if the problem is incompatibility or a bad ignitor, but it was guaranteed good, so I suspect the VF500 ignitors just don't work well for the bigger bikes. I keep it for emergencies.
A known-good ignitor from a 250 Rebel twin did not work at all in the 1100. I also have never seen a cross-reference either official or unofficial indicating that the VF700 will work for the VF1100. The VF700s are kind of odd anyway, although as I mentioned, the connectors are the same for all of them. I do know that the VF750 works in the CB900, but they don't seem to be completely interchangeable. The new OEM CB900 did not work well in the VF1100, even though the VF750 works in both. Go figure.
The VF750 ignitors also seem to be more expensive. I don't know if there are fewer of them around, but I had better luck finding VF1100 ignitors. Parts can be cross-referenced at Bike Bandit (bikebandit.com), although the system runs pretty freakin' slow sometimes and there is no way to know if a one-digit difference in a part number is critical or not. Bike Bandit also has pretty good prices on tires and such, but their OEM parts are steep for my budget.
So now get your carcass out there and take something apart.
