Coil question

Should your coils get constant power when the key is on?

 

once the power passes through the ignition switch, the ign. fuse and the engine stop switch, yes. the coils should have constant power to one side of the primary coil winding. the other side of the primary windings ground through the igniter.

CN

 

Ok thanks. What is the minimum voltage it needs to make them fire properly?

 

Ok so can't get any fire. I checked some voltages in different spots getting 12.4 volts to the coil can anyone tell me what I need to check next?

 

ebay for a service manual...

http://www.ebay.com/sch/i.html?_trksid= ... &_from=R40

CN

 

Are you checking for spark with the plugs out & grounded to the head ?

 

The Haynes book for the XJs says,

"The TCI unit also incorporated a coil protection circuit which switches off the supply to the coils should the ignition be left switched on without the engine running for more than a few seconds.

"When the starter is next operated, the supply to the coils is restored after the crankshaft has turned 180 degrees"

But this can't be quite right, since there is a supply to the coils at all times when the kill switch and the ignition switch are both in the on position. (As cyclenoob says) However, no current is flowing through the coil because the circuit is switched off inside the ignition module (TCI unit) so the coils don't get hot and don't fry. (I assume here that what Haynes says about there being a coil protection circuit is right)

I have to go out now, but a couple of things to think about: 1) Sometimes you get dry joints inside the ignition unit, which need to be resoldered. I had a 60mph XJ750 until this was done. 2) Most electrical problems are mechanical; a poor connection. Don't forget the live feed to the ignition module.

 

I'm back. Use a bulb tester and see if it lights brightly, when checking at the live (supply) side of the coil. If you don't have a bulb tester an old indicator with a 21w bulb will do. Then try at the live supply to the ignition circuit, just remove the multipin plug and test there.

This will prove whether there is or is not battery voltage and good enough connections throughout the supply circuit to let you have the current you need.

Resistance readings: (From the Haynes manual)
All at 20 C /68 F.

Coil
Coil low tension (LT) 2.5 Ohms +/- 10%
Coil high tension (HT) 11K Ohms +/- 20%

Pickups:
One blue or black wire, (Haynes is not clear about the colour) to orange 700 Ohms +/-20%
The other blue or black wire, to grey 700 Ohms +/-20%

 

http://www.xjbikes.com/Forums/viewtopic/t=27543.html

 

Thanks guys. I will definitely order the service manual for starters. Yes that's with the plugs grounded to the head and nothing no spark at all. I have checked the voltage at the ignition switch. At all the fuses and they are all the same as at the battery with very little difference. The bike was running sometimes you had to let it set a few minutes after running before it would retire but ran great. The last time it ran it ran long enough to get the pipes hot then died like someone shut the key off. Very frustrating for someone who doesn't know alot about motorcycle electronics.

 

Don't like to be pessimistic, but that sounds like the TCI.

 

So it would still get power to the coils if the tci was screwed up?

 

It *could* get power, if the coil voltage isn't being cut off after a few seconds then I'd say your TCI isn't operating correctly.

 

That's actually an easy way to check the system. Have the plug out grounded against the engine, turn the key on. After a few seconds, you should see a spark at the plug, as the TCI turns the power off.

 

Ok I will try that. If I don't get a spark after a few seconds then it's the tci? Or could it be a bad connection?

 

When this first started I had a plug out checking for fire and nothing except every once in awhile after cranking looking for spark it would spark just as I released the starter button. I thought I would share that in case it would make a difference.

 

It sure does.

"Firing when the button is released" is a classic symptom of a slightly weak battery; OR a starter that is drawing too much leaving nothing to fire the ignition with. As soon as you "unload" the electrical system it has enough juice to fire.

 

Ok thanks Fitz. I'm absolutely sure it's not the battery as it is brand new and I have it on a maintainer. Should I check the voltage going to the coils while I'm cranking it to see if and how much it draws?

 

Yep. You can check for a weak battery/dodgy starter motor by using jump leads and another, good condition 12 volt battery, like the one in your car. Connect the batteries just as you would to do a jump start.

It might still be bad connections in the supply to the coils and to the ignition module, so do the bulb test separately as well. I forgot to say that while testing the ignition module feed, put one wire from the bulb tester to the live supply for the module and the other one to the earth connection for the module, so testing both live and earth at once.

 

Two thoughts on car batteries.

One. No experience here, but I have read that if you jump from a car to a bike, the car should NOT be running. Too much juice. So, ALMOST the same as jumping cars.

And, two, I used to assume that a "new" battery meant a "good" battery. A few months ago I put a new battery in my truck. One week later my truck would not start. Even my long, long time veteran car mechanic replaced my starter before he would consider that it might be a bad new battery. No good. On a whim he replaced the battery I had bought which tested fine. With that new battery from him, the truck has been fine ever since. The battery place gave me a refund despite a policy of replacement only.

I also agree that the "firing when button released" thing is real. My Maxim did exactly that. New battery and I'm down the road. Happy I sprung for a AGM sealed unit.

Good Luck.

 

As above, being new doesn't mean it's good or if good, that it's not just slightly flat.

It's not the ignition drawing the power. It's the STARTER; a sluggish or gummed-up starter (or a less than happy original solenoid) can draw all the available power leaving nothing for the ignition.

 

The charging voltage depends on the battery type and it is still a lead-acid battery, so it doesn't matter if the car is running, assuming the car's voltage regulator is doing its job.

As for thought two, you are absolutely right; a new battery isn't always a good one. I found this out on a bike that would not give me a charging voltage. That's why I said to use a good condition battery. (If it starts the car okay, it's a good'un!)

 

I'll try the jump start idea. I am a bit confused as to if this would make it shut off while already running though.

 

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I am a bit confused as to if this would make it shut off while already running though
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yes it would, assuming you mean "running but stationary"
the bike wont start charging till the motor is spinning at around 2500 revs,
anything under that and the bike will be draining the battery, and eventually the motor will stop.
so you're draining an already weak battery, hence the few minutes running
stu

 

Hmmmm ok I'll try all of these great tricks/ideas. I really appreciate the help guys. I will keep you posted on the results. I'm sure I'll run across some other things that I won't be able to figure out.

 

this guy does a pretty good job of running through troubleshooting the xj ignition system...

http://www.youtube.com/watch?feature=pl ... m3qbI#t=94

CN

 

Thanks cycle. I just ran across that same video and watched it a few minutes ago. It definitely helped me out since I'm more of a show me kinda guy. Lol alot of the explanations get me a bit confused.

 

It could also be a completely different problem causing that. The bike is nearly 30 years old, remember?

If you don't have a service manual yet, you're going to need one and soon.

You're also missing my point. If there is something OTHER than the battery causing the problem, like a gummed-up starter, all you'll do by hooking up a larger capacity battery is to possibly get it running while masking the true issue, and probably spending money on a new battery when it wasn't the culprit.

The bike should crank AND fire off its own battery.

Step one: fully charge the new battery and take it to an auto parts store and have it load tested.

Step two: install a brand new set of the correct spark plugs, properly gapped.

If it still only fires when you let go of the button, you need to have a close look at the solenoid and the starter as well as the wiring and connections between those.

"Tricks" don't work. Shortcuts don't work. Something is sucking all your juice or it would fire. DIAGNOSE. For that you'll need a book.

 

I agree Fitz. I ordered the book this morning. I will take the battery to the parts store and have it load tested. I've heard the scenarios of trying to cheat so to speak. I definitely want this bike to be safe and sound when I get it on the road. I am also enjoying the whole learning process that goes with it. If it was an 85 car or truck I wouldn't have to do all this research Lol. Anyway I truly appreciate all your guys help and ideas. With me being new to street bikes I'm sure I'll be on here alot more than I would like to admit but again I'm enjoying this part as much as the actual riding.

 

great video thanks i guess i am lucky not everyone has twin bikes one running and one not

 

This might be of some use

 

Ok guys so I got a few minutes last night to run some more checks on some of the safety switches. I might possibly have came up with something. The kickstand safety switch relay could possibly be bad. I have not received my repair manual as of yet so I don't know how to test this but I took it off and when you shake it it sounds like something is rattling around inside it. I know this is probably a dumb question but is it supposed to rattle like that? Can anyone tell me exactly how to check this? Thanks for any information.

 

Courtesy Chacal at: http://xjbikes.com/Forums/viewtopic/t=27543.html


"BY-PASSING SWITCHES AND RELAYS:

How to bypass various relays: first of all, our advice is DON'T. The relays and switches are there for a reason....your safety, to prevent "mistakes" from turning into "disasters".......so our recommendation is to just leave the system as it is, and replace any components that fail. However, for failure testing purposes, it may be necessary to temporarily "by-pass" certain components, thus eliminating their functionality from the circuit, to see if they are the source of whatever problem is occurring.

Sidestand (kickstand) switch:
- twist the two (or three, depending on the model) wires together and ground them. Grounding the wires is the only way to complete the circuit that activates the sidestand switch relay.

Sidestand (kickstand) relay:
- unplug the safety relay which disables the whole bloody mess but DO NOT leave it that way, fix it right!"

One of many things I have PDF'ed and added to my Kindle, which also has the factory service manual and goes with my tool kit on the road.

 

So if I just unplug it and if that's the problem then it should fire? If this is the problem how is the best way to go about finding a new one?

 

Well I unplugged the kickstand relay went to check for spark. I hit the starter and it instantly started hitting off the 2 cylinders that I didn't have the plugs out of so I put it all back together and got it to run for a few seconds. Since its 20 degrees out and I don't have the tank on it or gas hooked to the gas line. I was fairly impressed! Now back to the rest of my list of things I'm gonna do to get it safe and road ready. If the weather ever warms up! Thanks everyone for the insight on this one. I much appreciate it. I'm sure I'll be back soon with more issues.

 

If you go to the Xj forever catolog in the electric section Len put some very detailed directions for trouble shooting all the sections of your ignition system in there. I just fixed a similar problem on my bike, ten minutes ago, with only intermittent spark with my battery fresh off the charger and the culprit was actually a bad connection between the boots and coil wires. If you want a PDF copy of the service manual while you are waiting for yours to come in the mail message me and I will send you one.