OEM Ignition coils for XJ550

I'm having difficultly finding replacement coils for my XJ550. The 3 I've bought off of eBay were bad with too high of a resistance and i can't get any sellers to ohm out any for me before I buy.

However, I'm too cheap for the Dyna coils. Does anyone know where to find new(er) or remanufactured coils for my '82 XJ550? Even Old Bike Barn doesn't want to show me any love.

 

Have you considered cutting off the high tension leads and soldering in replacement line? If the readings are high, dollars to dougnuts the copper core on the high tension leads is corroded. On the flip side, the high resistance measurement also infers that the coil windings are intact. $15 in material ought to set you in motion.

 

Hey MimiMax, I have some nice used coils available (stock) that have been ohmed and are within spec, cases not cracked. Or I also have spark plug wire SPLICERS that allow you to splice in a new piece of plug wire onto a stub of your original wire, and that's the cheapest way to go as long as your primary resistance (2.5 ohms +/- 10% at 70-degrees F) is okay.

Also brand new Yammy coils, but they're more expensive than the aftermarket Dyna coils....but much easier to install!

 

When I ohm-out the wires by themselves, they're pretty close to zero. The secondary coil reads 11kohm w/o the plug caps and +24k with them. So I think it's the windings that are high.

On a side note: I was surprised to find that there's resistors in the caps, but after reading up a bit I guess they're necessary (had a moment of elation when I thought I could just go and buy zero ohm caps).

Is there any way to reduce the resistance w/in the coil pack (sounds risky, but figured I'd ask)?

Charcal: how much for a pair of the used ones?

 

11K ohm secondary resistance (w/o the plug caps) is a correct reading. The PRIMARY side of the coils should be 2.5 ohms, +/- 10% (in other words, 2.25 to 2.75 ohms). Note on the primary side it is single-digit ohm values, not "thousands of ohms" like on the secondary side.

And no, there is no simple way to "rebuild" a coil. I suppose that somewhere in the world there's a mad-scientist type, holed away in a dark, dusty corner of The Utility Coil Research Lab Co., that takes apart and rebuilds old, weary, broken used coils, but........it's an extreme thing to attempt to do.

Also, the plug caps should really be about 5K ohms each, so if you read the secondary side w/o caps and it's 11K (that's great) and WITH the caps it's 24K, then you have bad caps (about 13K total, or an average of 6.5K each, or it might be one good cap at 5K and one bad cap at 8K, etc.).

Yes, I also have NGK caps available, too.........

And you CAN use 0K caps, if you wish, no harm, no foul. Only problem is that NGK's only 0K cap is a tiny, short 90-degree cap that doesn't work too well on the outer cylinders, and basically not-at-all on the inner ones.

Good used coils, no caps, $ 45/pair plus shipping. Caps are listed in my ad if you find you need to replace some.

BTW, how did you measure the wire resistance only? Did you poke a hole in one of the plug wires with the ohmeter lead? If so, make sure you tape it up, shrink-wrap it, or use some paint-on electrical tape, as it will leak voltage through that tiny hole (makes for a "shockingly" pretty light show at night!)

 

Speaking about sellers who won't ohm-test coils, here's two of my favorite responses that I've received from potential sellers of used coils when I asked them to check their coils for me before I bought them (and I even explained to them in detail and provided them with a diagram showing how to do it):

1) "for 10 dollers for these coils and you want me to go check them with a meter i said in my list they are good take my word or go down and buy new ones "

Well!

2) "All my parts are guaranteed. I have never had a part returned. I try to purchase only running bikes. If these coils are bad, I will pay roundtrip postage and refund your money. I have had 22 emails to go through. At some point I have to watch Football. This email looked really bad when I was proofreading it. It made my head hurt. Thanks for the info..."

Well-well!!

*********************

Finally, if you are using a analog (moving-needle) ohmeter to measure resistance, always remember that each and every time you measure for resistance to "zero-adjust" the ohm meter or you will get inaccurate readings. Digital meters normally self-zero.

 

not that I should put too much belief in it as it listed secondary resistance should be measured between "either primary lead and the spark plug cable", but my Clymer shows measuring resistance with the plugs on. Is it really that wrong?

No more relying on my memory, I just remeasured: I've got 2.7ohm on the primary, 12.2k on the secondary (w/o caps), 4.98ohm on one cap and 5.86 on the second for a total resistance of 23k. The wires are indeed 0 ohm. So if I replace one cap I can get it down to 22k at best.

However, the spark that I get is so weak that I need a couple of sprits of starter fluid to get it to light. After it gets going it runs fine, but there's no way I can get it going in the winter time (I'm assuming colder engine pulls more juice from the starter, robbing it from the plugs).

I've already rebuilt the starter thinking that that was the problem, and thought I'd narrowed it down to the coils. Maybe it's something else? I'm all ears.

{ I measured the resistance of the wires at the base beneath the rubber bootie in case this coil was actually good - nice catch though}

 

yeah, I have a real hard time believing that these chop-shops don't have a multimeter (come on, there're $4 at harbor freight). I always figured it was more likely that they knew the coils were bad.

 

Well, I've always read in the factory service manuals that the specified secondary resistance for the factory coils is 11K +/- 20% at 68-degrees F. This translates into an acceptable range of 8.8K to 13.2K. The factory manual (as do the Haynes manuals) show measuring this resistance WITH THE PLUG CAPS IN PLACE (no plugs, though), but I don't see how that could possibly be right, as the plug caps JUST BY THEMSELVES are a total of 10-20K resistance....which would automatically put every coil out of spec! (I say 10-20K because on some models, 5K plug caps were used on the #1 and #4 lead wires, and 10K caps were used on the #2 and #3 caps, so the total resistance of just the caps is either 10K or 20K, depending on which coil is being measured---how can you have a "standard" of 11K +/- 20% FOR A COIL when the caps vary so greatly?).

BTW, if your spark plugs are non-resistor plugs (no "R" anywhere in the spark plug model number), then unless there's a problem with them, their resistance is zero.

I truly believe---and anyone who knows different, please chime in here!---that the factory and aftermarket manuals (who seem to have copied, diagrams and all, the factory Yamaha manuals) are wrong: it's 11K secondary resistance OF THE COIL'S SECONDARY WINDING that is the "real" spec. Brand new Yamaha coils that I've measured (w/o caps) are in the 11K range.

There is no way that the secondary resistance is measured between a primary lead and a secondary (plug wire) lead. Electrically-speaking, that makes no sense at all......

Sound like your coils are "okay", the 2.7ohms on the primary side is right up at the upper range of allowable readings (2.75 is the max, and that's at 68-degrees F, and the hotter a piece of wire is, the higher it's resistance; thus if you are measuring 2.70 ohms with the coil at, say, 60-degrees, then it's actually close to 2.75 or above at 68-degrees).

All that being said, 2.70 ohms or even 2.75 ohms is within spec, and is therefore probably not the root cause of your problems.

23K total secondary resistance is, again, "okay", but at the high end. Remember, the factory secondary spec is 8.8 to 13.2K, throw in two 5K caps, and 23.2K is at the top end of the allowable range. You're at 23.04K total, you're standing at the very edge of the abyss but you haven't fallen into the deep, dark, bottomless pit of electrical purgatory yet....at room temperature, at least.

Did you make sure that your ohmeter was zeroed before performing the readings?

Well, it might be a weak spark, or it might be something else. Combustion requires spark, compression, and fuel. How's your fuel? How do you know? Are your starter jets clogged? Carbs been rebuilt? Fuel in the bowls (after an overnight hiatus)? Do you have 12V AT THE COIL PRIMARY LEADS? Bad electrical connections throughout the (old) harness, poor grounds, etc. might be "robbing" your coils from getting their full dose of battery voltage at the coil inputs, and thus the output will of course be "weak"----even if the coils are top-shelf. Is your battery in good shape? It should read about 13.8V fully charged (before cranking). WHILE CRANKING, a volt meter across the + and - battery terminals should not fall below 9.5V...if so, your battery is weak or something in the electrical system is sucking juicy-juice really bad.

 

wow, I think I'm getting deeper down the rabbit hole. There's definitely something draining the juice before it can excite the primary coil.

I've always had a problem keeping the battery full and so I've got trickle charger on it 24/7. Even with that, it's reading 13.2v with the key in the off position. Turn the key on and the voltage drops to 12.6v and starts dropping; fast (about 0.1v/s). However, when i turn it over the voltage across the battery sits about 10.3v, which is sounds like might be okay. On to the IC unit...

The voltage across the input to the primary coils was hard to read as it bounced around as it tries to fire, however between the R/W wire and ground it was 11.1v with the key in the on position and 7.9v while starting. ding, ding, ding, do we have a winer? I hope so.

I'll spend some time tomorrow evening tracing the input voltage to the IC back to the battery to see if it's something obvious. Any suggestions on where to start? Now that I'm not hung up on the coils, I'll check the regulator, pick-up coil, and other ignition compoents to make sure that they're within spec.

I have a hunch that it is electrical because as long as I've had this bike (2 years now), it's always been a bugger to start. I cleaned the carbs last summer and went through many tanks of gas with the same behavior. The mixture might be off, but after it gets fired up, it runs fine.

BTW: Yeah, I've got a fairly high-zoot DMM that was a going away present when Tektronix laid me off. It shouldn't have a problem re-zeroing.

thanks for all your help!!!

 

Wow, I'll have to defer to other experts on the 0.1V/second drain with the key on---sounds weird. If your battery won't hold a charge you've got a bad battery or a bad charging system (regulator/rectifier, or generator brushes......search these forums for generator (or alternator) brushes, there are many threads about them and it tells you how to check them
(yep, I've got new ones available!). Also you should perform the commutator resistance checks and the diode tests as described in the clymer manual......the regulator tests take 2 multimeters to perform, somewhat complicated.

Unfortunately there is no way to "test" the TCI unit, as per Yamaha. You troubleshoot EVERYTHING else and if you still think you're having electrical problems (as opposed to fuel or any other problem that could cause the exact same performance symptoms, ha-ha Catch-22), then you should replace the TCI unit with a known good one (off another bike!) and see if that fixes the problem. O-kay.......

And for a great, final kick in the petcock, the TCI unit is no longer available new! Or aftermarket (actually, they are, but they have some questionable reviews about them). And, get this: THERE'S NO KNOWN WAY TO TEST A USED TCI UNIT FOR PROPER FUNCTIONING (besides installing it on a bike and running it). So forget asking eBayer's to test them, 'cause even if there wasn't a football game to watch, there's no way to test them, anyway!

Your rabbit hole beckons. It's a lot like an abyss. Say hello to the Red Queen for me when you get there. Go ask Alice, when she was still small.....

 

Oh BTW, cold engines don't really require much more voltage to turn over....in fact, one of the PROBLEMS with these Yamaha's is that their starters are real overkill, they'll spin the engine plenty fast even if the battery voltage is really low, far too low to provide enough trigger signal to the TCI/coils. Batteries produce much less voltage when cold, that's what accounts for "slow winter cranking". But you have yours on a battery tender 24/7, so that negates that problem.....

The other thing that causes hard starting during cold weather on carb engines is that it's too cold to allow the fuel to boil---yes, boil!----as the cold temp obviously reduces the ability of the fuel to vaporize (the greatly reduced atmospheric pressure caused by engine vacuum drawing a rush of air over the fuel jets not only draws fuel into the intake tract, but it does so by "vaporizing" the liquid fuel into a gaseous mist. Liquid turns to gas when it boils. Liquids boil at around 200-degrees farenheit at "STP"---Standard Temperature and Pressure (temp = 70-degrees F, pressure = 1 bar = 14.7 psi = atmospheric pressure). Reducing air pressure to almost "nothing" (that's what a true vacuum does) changes the temp at which a fluid boils at---dramatically reduces it. The venturi in the carb throat is what does the trick to reduce the air pressure, thus creating both a "pull" on the fluid AND ALSO CAUSING THE FUEL TO BOIL into a gaseous mist which is easily sucked into the engine.

So reduced temps in winter do two things:

1) results in a weaker battery output (reduced voltage output due to the slowdown in internal chemical reactions in the battery due to colder temps = reduced voltage available), and....

2) reduced vaporization of the fuel mixture....it's harder to make fuel boil when i's cold outside!

And those two factors in unison are what make carb-ed engines a bear to start in cold weather....

I know you were waiting all your life for this explanation. You're so truly welcome!

Now back down into your rabbit hole.......!

I think you're going to need this before it's all over:

http://216.109.125.130/search/cache?ei= ... 1&.intl=us


I would print the above page out, because the original page has already "disappeared" from the web, but thanks to the google way-back machine, it's still available as a cached version......for now. Absolutely invaluable info!

 

I wonder if we could host his work in our Download section or a sticky post? :?: It would be nice to capture before it gets lost from the google cache.

Has anyone tried to contact Aaron Berg to see if we could? :?:

I did find a yahoo profile last updated in 2004 under the search for the email address on that doc., but it is missing any usefull information. :cry:

 

ohhh... secret electrical trouble-shooting manual. This is worth it's weight in gold, and look what he says about primary resistance:

- good call Chacal and Thanks!!

I'll begin with the big parts (rectifier and regulator) before I start tearing into harnesses, but i wonder has anyone tried to fake out a TCI by feeding it a known clean supply voltage (from a DC power-supply)? I suppose if i had a known good battery that might do the trick. I'll grab an oscilloscope from work to help troubleshoot as well.

BTW: FANTASTIC description of why bikes don't like cold weather. I had searched for something like this, bit it was in vain. I always figured the cold oil caused the engine to require more torque to turn over which is why they sell oil-pan warmers to help starting. Seems like you'd be better off putting the warmer on your fuel tank or carb...

 

JeepSteve....yes, I tried contacting him a while back and no dice. Hopefully someone, somewhere, knows how to reach him....he's kind of an XJ God in certain aspects of knowledge and experience and I hope to be like him someday, when I finally grow up.

Cold engines do require slightly more torgue to turn over, due to increased oil viscosity, but not as much as you would think. Electric starter motors with torque multiplication via large flywheels produce quite a surprising amount of torque.....more than enough to overcome the flow resistance of single grade or the even thinner multi-grade oils (not to mention synthetics). Until the temperatures become REALLY cold.....below zero F....it just isn't really an issue. The main issue has to do with the reduced voltage available from the battery----batteries produce voltage via a chemical process that occurs at a certain rate at a certain temperature---reduce the temp and you reduce the chemical interaction---and thus the voltage. These chemical processes are highly temp-sensitive. BTW, if you buy "home" batteries in bulk packs (like at Home Depot, AA, AAA sizes, etc.) you'll make them last ALOT longer if you store them in the frig-----these batteries are also producing current via a chemical process, and "use up" the chemicals in the process, whether there is a load attached to them or not. Storing them in cold temps. significantly reduces the rate of chemical processes within the batteries and thus extends their "shelf-life" by a considerable amount. However, temp extremes are not good, so don't put them in the freezer or let them freeze!---this will result in significantly reduced life. Best to store them in a sealed baggie, too, as the ultra-low-humidity achieved in modern frigs will dry out not only your left-over meatloaf, but also your batteries, too, and that's never a good thing (batteries actually have plastic insulator shields to prevent this, but they're not perfect).

Yes, a true engine warmer would concentrate primarily on keeping the battery (or battery fluid) and the fuel pump or bowl warm and toasty, somewhere around 80-degrees F.

 

MiniMax....yes, you can tear into all the "black boxes" in your system, but if you read all the way through the top-secret how-to-get-electrically-rich article, you'll notice that Mr. Berg goes over and over and over again about the importance of making sure that all of the electrical connections are good (meaning they have as minimal resistance as possible). He does that for a reason....it's absolutely true. People ignore it for a reason....it's a pain in the arse to check, clean, solder and/or re-solder, check voltage drops between each and every connector, etc. BUT.....it is all "sad but true".

Wire is pretty stable unless the insulation is damaged, and all those black boxes are pretty stable unless some injury has been done to them. The connectors and the operating surfaces (like the alternator brushes, starter switch commutators, etc.) are what wear or get deteriorated (electrically-speaking) and those are usually hard to service (or not designed to be serviced).

Your rabbit hole beckons. It's dark in there---until you reach the light at the end of the tunnell!

 

On the thought of supplying a secondary voltage source to the primary side,,,,,
old cars ran a wire from the starter solenoid to the primary,,,,this would bypass the built in resistor to the primary resulting in a hotter spark while cranking,,,,,
do we have any knowledge of a resistor in the primary circuit or the benefits of bypassing any built in resistance,,,or if the system could handle this(diodes for instance)???

 

I like all the info posted here. I just wanted to add, that when I needed a new coil on my XJ550, I just purchased one from Bob Tracey's World of Cycles for approximately $70 or so...

 

Hey there, your idle voltage across the battery should be 13.2 or thereabouts. 10.3 is too low, your regulator is shot or your alternator bushes are toast. Either of these issues will cause a no start condition.

 

Hey Robert, I think he meant that WHILE CRANKING THE BIKE (starter engaged) that the voltage was 10.3 volts, which is an acceptable reading. If he meant at idle, then yes, way too low!!

 

Yeah:

Sorry for the confusion

BTW: Anyone know where to find plug-cap resistors? I pulled my caps apart and when I reassembled, I can't get them to read anything now. The resistor looked like just a chunk of porcelain and I couldn't measure anything on it. weird

 

Well, you're a crafty little rabbit!!

As long as you have good electrical continuity thru the plug cap, don't worry about it.....you've converted your 5K cap to a 0K cap, which won't hurt anything at all.

If you have no continuity, maybe stuffing a short length of copper rod in there will work (same size/length as the resistor)?

Or you can buy replacement plug caps pretty darn cheaply:

Inner Cylinders:

HCP1316 NGK Plug Cap, 5K ohms, short 90-degree angled boot, for 12mm "D" plugs with a threaded stud on top. Great replacement for the stock plug caps on the outer (#1 and #4) cylinders. Slightly taller than original caps (1.5" tall for these replacements versus 1.3" tall for the originals). Each.
$ 4.00

HCP1322 NGK Plug Cap, 5K ohms, medium 120-degree angled boot, for 12mm "D" plugs with a threaded stud on top. Suitable replacement for the stock plug caps on the outer (#1 and #4) cylinders. Slightly taller than original caps (2.5" tall for these replacements versus 1.3" tall for the originals), and the 120-degree angled plug wire end offers some additional clearance as compared to the stock 90-degree right-angled caps. Each.
$ 4.00


Outer Cylinders:

HCP1312 NGK Plug Cap, 5K ohms, straight, for 12mm "D" plugs with a threaded stud on top. Recommended as a suitable replacement for all four XJ700-X plug caps, as the straight-up design helps keep the plug wires off the valve covers, unlike the angled-tip configuration of the original style caps. Can be used on XJ550 inner cylinders (#2 and #3) as replacements, especially when using aftermarket plug wires and coils. Approx. 3" tall vs. the 2.5" tall originals. Each.
$ 4.00

HCP1318 NGK Plug Cap, 5K ohms, tall 102-degree angled boot, for 12mm "D" plugs with a threaded stud on top. Similar in design to all four XJ700-X original plug caps, with the bent-up plug wire tip design. Recommended for the XJ550 inner cylinders (#2 and #3) as replacements for the non-available tall 90-degree tip caps. Approx. 3.25" tall vs. the 2.5" tall originals. Each.
$ 4.00

 

well, I doubt anyone'll be surprised, but Mr. Berg was dead on. When I measured the resistance between the + side of the battery and the main or ignition fuse I got somewhere in the megaohm range; not good.

Some sanding and a spritz of WD-40 and now the resistance is less than an ohm (I can't believe that it ever started before). I now have "rebuild/replace the fuse box" on my to-do list - I noticed that there's a great DIY on the forums too! I love you guys!

In order to get the plug caps to work (reassembled they read open), I had to make little resistor burritos with some tin-foil. I doubt it'd work for a long ride, but perhaps it'll be enough to get the bike going so I know what all I need to replace (new caps, check). I then cleaned up the connectors feeding the ignition module and the connector between the solenoid and fuse box.

When I turned on the key, I'm still getting the weird voltage drop, but the spark looked about twice as big as before. yeah!!! I think I'm on to something.

To explore the voltage drain further, I pulled the connector to the rectifier and remeasured the voltage at the battery when the key was in the on-position and observed the same drain; bummer. However, I also discovered that main power wire (R/W insulation) to the rectifier was obviously very corroded and high-resistance b/c it was actually starting to melt the housing!! Again, according to Berg's electrical FAQ, I was probably overcharging my battery. Good to know (new rectifier harness, check), and it might explain some of my starting issues to someone more versed in the black-art of automotive electronics than I.

I think I'm really on to something here. I'm going to walk through each component and connection that might lead to a voltage drop and make sure that it's clean. Turns out the light at the end of the tunnel was actually a reasonably fat spark!! Sweet! I'll let you know how it turns out after replacing some of these obviously bad parts. Thanks again for all your help.

BTW: Where'd you get the $ quotes on the caps? There're $6 on old-bike-barn. I'd love to find a place to drop some $$ on replacement parts rather than multiple ebay bids.

 

Not that my previous post was premature, but I'm getting a bit confused over why I'm getting certain readings when based on the schematic they should be different.

Case in point: I measure the resistance between the main and ignition fuse with the battery disconnected and it's zero or open depending on the position of the kill switch (see image) . Okay, that jives with the book. But then when I reconnect the battery the resistance jumps 1.2k. Here's the weird par: disconnect the battery and it only drops to 0.8k. It takes removing the main fuse and reconnecting the DMM before it will drop back to zero. It must be latching something (relay, transistor, etc) closed and then it won't reopen, but that still doesn't explain why the resistance changes between the two points that have nothing but wire in between (again, according to the manual).

I had the regulator disconnected while doing this so as to pull it out of the equation. I think it has something to do with the lights as when I hit the turn signal, the resistance would change (up to 1.2k). I also noticed that they're in the mix when the main switch is on, so that's where I'm going to focus next.

I'm sure there's a logical explanation for it, but things like this are why troubleshooting electrical system is such a pain. 'Nuff preaching to the choir...

 

I sell a lot of this stuff, most of it is listed in my ad over at:

http://www.xjbikes.com/Forums/viewtopic ... rt=45.html

A tin-foil burrito resistor. Wow, I'll have to carry those, too---everyone will want one now!

Glad that you're making such progress. Are you sure your MM is working correctly? Don't they use a small amount of current when in resistance-testing mode? Perhaps you're seeing a phantom remnant of current from the MM rather from the ignition system?

Your internals in your switches might be really corroded and dirty, too, the insides of the switch housings are moisture traps. Have a peek inside.....

You may want to invest in a small tube of di-electric grease....would be longer-lasting than WD40.

Yes, your charging system was probably overcharging, I was going to suggest that the other night when you mentioned that you have to keep adding water to your battery.

That means you're going to end up cleaning EVERY connector on the bike, and coating each with some di-electric grease, and re-connecting. Start from the back of the bike first, by the time you work your way up to the front you'll be more of an expert at cleaning and lubing them and can slam through the 50 zillion of them up front just that much quicker. Have you ever peeked behind your headlight, inside the housing? I assume your MM has diode-checking capabilities, might want to check out your diode block, too, just for ghits and siggles.......

P.S. I got your enclosed, 6-space ATC fusebox, too!!

 

Vroom Vroom!!! It's alive!

I've never had my bike start that quickly (unless it's already really warm). Sweet!

I cleaned out the caps I have and shorted them with the tin-foil (and everything else listed above) and it fired right up. It's amazing how corroded those caps were. I would recommend to anyone with the original Yamaha caps to replace them immediately!

I'll work on the voltage drop after I get the new fuse box and caps.

 

so your plug wire boots were bad? Looks like chacal will be making a sale.

 

He already did! I just wanted to make sure that that's all it was.

 

thats pretty cool! are newer bikes easier to work on? haha. With my Xj let me tell you Im never bored theres always something to do.

 

Anyone know where that electrical FAQ migrated to? The link above no longer works. Maybe someone made a local copy of it that they could post or email to me?

Thanks in advance!

 

I just tested it. It works. Try pasting this address : http://www.xjbikes.com/Forums/viewtopic ... rt=45.html.
Good luck.

 

This is the link I was referring to...
[quote="chacal]
I think you're going to need this before it's all over:

http://216.109.125.130/search/cache?ei= ... 1&.intl=us


I would print the above page out, because the original page has already "disappeared" from the web, but thanks to the google way-back machine, it's still available as a cached version......for now. Absolutely invaluable info![/quote]

Thanks in advance!!

 

aftermarket on ebay, and amazon. $30
Model: Db Electrical IMC0016 Ignition Coil

 

are they bolt on replacments?

 

I hope someone got that link copied, cuz it's gone now------

 

is this the title of the page
TCI & CDI Electronic Ignition / Stators & Charging Systems