Installation of Coils for Yamaha XJ1100

I recently purchased a non-running 1982 XJ1100. The previous owner had already disassembled the coils, so I have no idea how they were installed originally and finding pictures/good diagrams for the XJ1100 is very difficult. I have four major questions: 1) do you install the coils with spark plug wires that come out of the coil pointing toward the rear or front of the bike (it looks like the coil could be mounted either way (with is correct)? 2) does it make a difference which side each coil is installed on (are the two coils interchangeable or is there a left and right)? 3) once the coils are installed, which spark plug wire connects to which cylinder (does the left coil drive cylinder 1 and 4 and the right coil 2 & 3)? 4) I have 4 spark plug caps to install on the spark plug wires, 2 have 5 ohm resistance and 2 have 10 ohm resistance, which cylinders get 5 ohm and with get 10 ohm?

All of the above is simple, if I could just get a picture and simple diagram for an XJ1100, but I've searched online and can't come up with anything specific to the XJ1100. Any help anyone can provide would be greatly appreciated. Thank You!

 

The coils with the wires pointing aft, number one plug wire and number three on left coil , the right coil number two and four . As I recall at least . The caps should all be 5 ohms , caps are cheap and can be bought at most Yamaha dealers .

 

Thank you for your reply, very helpful! Are the two coils interchangeable? In other words is there a specific side for each coil (one has to be left and the other right, or it does not matter)?

 

The coils are different part numbers likely because of the different plug wire length and the primary wire color to match the main harness (orange or grey). The 1 and 4 coil mounted on the left will need the longest wire to reach the #4 cylinder.

The plug caps are also separate part numbers for 1,4 and 2,3, but not sure if that is a physical difference or electrical, or both. However, since you mentioned you have 5K and 10K caps I would suspect the 10K caps would end up on the 2, 3 cylinders, but that is really a bit of a guess

Edit: and after posting I noticed it was a bit confusing that the diagram shows different caps for the 1 and 4 coil, as well as the 2 and 3 coil, which would mean if electrical the order would not be as I stated above so I am a bit confused here

 

Thank you for your reply. The coil wire to cylinder order is different from the other reply I received. He said the left coil drives the #1 and #3 cylinder and the right coil drives the #2 and #4 cylinder. He also said all the plug wire caps are 5 ohm. Not a mix of 5 ohm and 10 ohm. Now I have no idea what to believe. I have searched on line for a diagram for the XJ1100 and I have found numerous configurations. Which is why I'm asking. Many diagrams are for the XJ750 and XS1100, which may be different. I'm finding that the XJ1100 is a rare bird with little available info.

Does someone own a good running XJ1100 and can just go out into their garage and take a look? Thanks in advance for the help...much appreciated.

 

@mlew is the resident XJ1100 owner, perhaps he will reply

That said, did you check the lengths of the coil wires to see if logic applies, especially if you consider the matching primary colors? Maybe the coil with the orange wire will only reach the harness connector with the orange wire if mounted on this side? And how about the plug cap lengths, on the XJ750 the middle caps are longer, which is very logical. And, are the numbers missing on the coil wires as they were banded with a number from the factory to make things easier and to look nice?

As for caps they are not that big of a deal and perhaps there are some variances between bikes. Len has them all being 5K in the Information Overload Hour.

https://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/

"XJ1100 models:

Pick-up coils:
120 ohms +/- 20% = 96 ohms to 144 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:
5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range"

Spark plugs:
0 ohms per plug

 

The non-resistor plugs are nla, only the resistor version is available now. Resistors in the caps are no longer required with the new resistor type plugs. I need to change the plug caps on my 83 750 Maxim this spring for the same reason. Some resistance is needed as it extends the spark duration, but too much resistance will start reducing the intensity of the spark.

 

Thank you for your reply and the link to amazing information. One last question: The primary side of my ignition coils measure 3.2 ohm, which is slightly out of the specification above of (2.25 to 2.75 ohm). Should I replace these coils? Is this too far out of spec? The secondary side of both coils are in spec.

 

At least put them on the “to do” list.

 

It's is easy to be off a bit on those with that low reading because of meter leads or poor contact with the terminals. Try touching the leads together and see what you get, and then try touching the same terminal and see what you get. It would be acceptable to subtract that from the reading, which will likely get you closer to spec if not in spec

 

So you can or cannot still purchase non-resistor spark plugs for a Yamaha XJ1100? Non-resistor plugs would require the resister cap and resister plugs would require a non-resister cap...correct?

 

A parts expert I am not, but it seems the non resistive plugs are getting harder to find, or even with some the terminal is not removable so they won't work. Perhaps @chacal our resident parts expert can weigh in again. I read a couple places that the BP7ES is coming back as a 2412 stock number, but you need the BP6ES, which is not quite as common among the XJ series anyway. Len (Chacal) does still list the BP6ES as available, but for how long??

And yes, if you select a resistor plug you would want to go with a non resistive spark plug cap

 

This is correct.

And re: other comments.

The factory parts diagrams are somewhat of a mess, mainly due to many "common parts" being superseded again, and again, and again........so what you see on-line (at Yamaha's or other websites using the CURRENT Yamaha diagrams/part numbers) reflects the currently available parts....which may not be the same as what a bike was originally equipped with.

In the case of spark plugs and especially caps (hence, resistance values), almost all of the XJ engines (except some years of some XJ700 engines) used non-resistive (0 ohms) spark plugs. MANY of the XJ engines use 5K resistive caps on all 4 cylinders (originally). SOME of the engines were specified with 10K caps on the center two cylinders. SOME engines...in some years....were offered with "noise suppression" plug caps which were 10K caps.

Oddly, when Yamaha gives the secondary resistance for the ignition coils, they illustrate that the checking procedure includes the resistance of the plug cap (in other words---plug caps installed on both plug wires while checking secondary resistance) when that is clearly incorrect......since, if one were to include 2 x 5K (=10K) plug caps in the secondary coil circuit, then there is no way to conclude that the total circuit resistance should be "11K +/- 20%" as the service manuals specify. This becomes even harder to accept if the model in question includes 2 x 10K plug caps (=20K, just from the plug caps!) in the circuit!

True "original part number" plug caps for the XJ1100 (and other models) are the 256-82370-00-00 which are 5K resistance. These have been superseded to the 4BP-82370-00-00 plug caps which are 10K resistance. Yamaha didn't seem to be too concerned with this change is spark plug resistance, as they continued to recommend the BP6ES spark plug, which is a non-resistive cap.

In reality, you're not going to be able to tell the difference in performance between have 5K and 10K secondary resistance when:

a) the ignition coils, caps, and spark plugs are within their correct specifications.
b) the engine compression, etc. are in good condition.

as Yamaha flip-flops in their parts recommendations / combinations in their own literature.

Issue "a", especially in regards to the ignition coils, is really key, as we note in our commentary in regards to "high-performance" ignition coils:

Of course, when considering the cost of new factory coils vs. aftermarket "high-performance" coils, then aftermarket "hi-po" coils can be less expensive, even though they may not have any better spark performance capability than stock coils! "Aftermarket" standard performance coils will also perform the same for some period of time, but tend to not last anywhere near as long as stock factory coils (which can last 25+ years in some cases) or the "hi-po" coils (which are generally built to tighter tolerances and use better internal and external materials in their construction).

Well, this is almost correct, depending on definitions, and I would invite @Rooster53 to chime in here, as he is more of a subject expert here than I am.........my understanding is that resistance in the secondary ignition coil circuit will merely "spread out" (in duration/time) the available spark energy (thus, since TIME is involved, think "volts per second (or, milli-second)" or "joules per time-measured".....and will not negate the total spark energy delivered in any meaningful manner (yes, resistive heat loss but that is somewhat negligible at these voltages).

So, for example (using round numbers and fictitious time frames), the coil outputs 10,000 volts and a 5K plug cap "spreads out" this voltage over 1 second----thus you are delivering 10K volts across the spark plug over the period of 1 second (and you can chop down that voltage into smaller and smaller time intervals, if you wish, hence 1000V per each 1/10th of second, etc.). Doubling the resistance to 10K then "slows down" the delivery of the same 10,000 volts (less any resistive heat loss) over a greater period of time......say 2 seconds, thus you have 5000V/second (or 500V per 1/10th second, etc.).

The "10K on the inner cylinders" situation probably has to do with one of 2 issues:

a) center cylinders run hotter, and perhaps slightly leaner, and in either case require a "longer" spark emission to fully light the mixture
b) on some models, the center cylinders are equipped with larger main fuel jets, again possibly due to center cylinders heat saturation, and thus require a longer duration of spark to fully ignite.
c) a combination of the above.
d) none of the above
e) something completely else

I've always viewed the 5K vs. 10K resistance issue as a "fine-tuning" issue, and for most people, in most conditions, you might be hard-pressed to ascertain any measurable difference in engine performance or plug life between the two situations. It may be an academic (rather than a real-life) issue, akin to arguing how many angels can dance on the tip of a spark plug electrode.



Oh, almost forgot: yes we still do have the XJ1100 stock spark plugs BP6ES (non-resistive) available, as well as their resistive (BPR6ES or BPR6EIX) versions:

HCP1290 Original BP6ES NGK SPARK PLUG, stock non-resistive plug is correct for all XS1100 and XJ1100 models. Each:
$

HCP1290SET4 Original BP6ES NGK SPARK PLUGS, set of 4.
$


HCP13512 Standard replacement BPR6ES NGK SPARK PLUG, 5K ohms resistive plug for all XS1100 and XJ1100 models. NOTE: it is recommend that when you use these resistive plugs (in place of the stock non-resistive plugs) that you also reduce the resistance value of the spark plug CAP by 5K ohms in order to keep your total secondary path resistance at the original value. Each:
$

HCP13512SET4 Standard replacement BPR6ES NGK SPARK PLUGS, set of 4.
$


HCP1291 High-performance replacement NGK IRIDIUM SPARK PLUG, BPR6EIX 5K ohms resistive plug for all XS1100 and XJ1100 models. NOTE: Iridium plugs should not be gapped, they are designed to be used "as is" out of the box. Attempting to gap/re-gap these plugs can and will likely result in electrode breakage! Also, because of their design, the color of the ceramic insulator around the center electrode will typically not show much color change as is common on standard plugs, and thus the ceramic color cannot be counted on to reveal mixture condition (i.e. lean or rich) accurately. NOTE: it is recommend that when you use these resistive plugs (in place of the stock non-resistive plugs) that you also reduce the resistance value of the spark plug CAP by 5K ohms in order to keep your total secondary path resistance at the original value. Each:
$

HCP1291SET4 High-performance replacement NGK IRIDIUM SPARK PLUGS, set of 4.
$

 

Thanks for the clarification, Chacal.