Need help solving this problem

Hello everyone

Cylinders 1&4 are not firing
First off, I've used the "search" feature before creating this thread. I've found a few related threads but nothing exactly related to my problem.

The best I can describe the problem is just a lack of power, it feels like I'm riding a moped now compared to what my XJ650 used to be like.

I rode the bike one evening and it ran excellent, just how it has been all summer.

Parked the bike that evening (outside), stormed/rained pretty hard all day the next day, then the following day after everything dried up I started the bike and it started just fine but was running really rough and took awhile for the engine to rev.

Tried to ride the bike even with it running strange, and the bike has no power!

What I've done so far:

Replaced spark plugs

Put the petcock into the "Prime" position

Checked air filter

Still runs poor.

Can anyone help me? The season is coming to an end for us in Wisconsin and I've gotta ride as much as I can before the winter sets in.

The bike is a 1981 Maxim 650

Thank you,

Paul-MaximXJ

 

I'd try replacing the gas. Maybe you got some water in the tank.

mikeg

 

I should have added that I topped off the tank yesterday with new gas (3/4 of a tank worth)

 

coils got wet possibly?
check your spark

 

Checked spark already and all plugs spark good

 

Water is heavier than gasoline. Topping off the tank won't do anything if there are "blobs" of water floating around in the BOTTOM of the tank, getting sucked into the carbs along with (some) gas. I would put the bike on the sidestand and then leave it TOTALLY STILL for an hour or so. Then disconnect the fuel line from the petcock, hook up a bit of appropriately-sized hose, and put the petcock on "PRI" and drain out a quart or two of gas. You'll probably get the lion's share of the water. Follow it up with some Sea Foam to "dry" the remaining water and you should be good. (Assuming it's not simply a wet wiring problem.) If it is water in the fuel, you might want to consider rebuilding your gas cap.

 

Sure sounds like something is wet still or has corroded. Try checking all the electrical connections - starting with your coils, the pickups, the TCI, Battery etc...

Make sure they are dry and clean.

 

Excellent idea. I have a feeling this is my problem.

 

I will be going through this tonight as well, hopefully with the combination of getting rid of the water if the gas (if that is my problem) and checking the electrical components I should have a properly running bike by the end of the night.

 

If you're going to be parking your bike out doors, you may want to invest in a bike cover. Just a thought.

 

Ok well I don't think it's water in the gas

I took the bike for a ride and checked the exhaust for heat

The outside two are hot/warm

The inside two are really hot!

I have spark on all 4.

 

park the bike in full sun all day.

 

It has been for two days :/

 

Have the float bowls been emptied ?

 

Try This,
Pull your plug wires off and blow out the caps & boots with compressed air. Take your plugs out and look to see if there are carbon tracks down the insulators to the metal. Put alittle dielectric grease on your plug boots pop the plugs and wires back on and see what happens when you fire it up. Moisture can stay in your boots for along time and may be shorting your plugs out. Maybe that will help. Good Luck

 

are there still puddles around the inner (2 &3) spark plugs? I would also try draining the carbs, maybe whatever water WAS in the tank got sucked into the carbs already, and it will do the same thing, lay in the bottom...

 

IF WATER RAN DOWN INTO YOUR AIR FILTERS AND SOAKED THEM, THEY MAY NOT DRY OUT UNDER THE SHADE OF THE SEAT.... ???/

 

I'm with Fitz - check the bowls

 

If you drain some fuel from the tank into a glass jar, and let it sit for a while, any water that is there should settle out and you should be able to see it. You can also start the bike at night in total darkness and look for sparking around the coils and plug wires. Should you see any, you can try using starting fluid to evaporate the moisture with the bike off, restart the bike, and re-test. Make sure that all of the ether evaporates before restarting, or you will have another issue to address!! That should help you determine if the storm was the source of the problem or merely coincidental to the start of some other problem.

Hope that helps, Mike

 

Well I think it's not a fuel issue.

I'm thinking I have a problem with the TCI unit

"Yeah, if only #1 isn't firing, it isn't a TCI or Coil issue. Both #1 and #4 fire at the same time from the same TCI signal so one cannot work without the other, unless there is a wire issue. What you should do is switch the signal wires (primary if you will) and also switch the plug wires (1&4 to 2&3 and visa versa). The dead cylinder should move to #2 then if it is a wire issue. I would also try replacing that spark plug also, it isn't unheard of for a brank spankin' new plug to be bad. If the dead hole does switch to #2, unscrew the cap, trim back the last 1/8" of plug wire or so and screw in the cap onto new wire. Make sure that the copper wire is at the end of the insulation and not playing hide-and-seek. While you have the cap off, check the resistance through the cap, I can't remember the spec though, but they are resistive caps."

^From another thread I was reading, since 1&4 are dependent on one another with the TCI unit, I'm thinking this is my best guess

 

I'd be thinking the coil might be bad before the TCU. Swap the coils over first to see if the problem follows the coil to 2 and 3. If it follows - bad coil. If it stays with 1 and 4, then you either have bad plugs (even new ones can be bad) or a TCU problem.

Good luck!

 

I replaced all 4 plugs when I first noticed the problem, also the cylinders (1&4) look to be on separate coils

 

If 1 and 4 are on separate coils on your bike you will have major running problems 8O

Have another look.

 

When I say coil I'm talking about one of the two things under the tank where the ignition wires attach two. Is this correct?

 

Yes. 1 and 4 should be on one of them, and 2 and 3 should be on the other one.

 

That's not the way it is on the bike right now, I've ran it all summer though and never had any problems?

 

Time for pics

 

Doh! I don't really feel like taking the tank off again :/

 

Paint magic

 

You got that wrong, Boss 1+4--------- 2+3

 

+1 it's wrong for sure the way it is. Are you sure you didn't mix it up when you changed plugs?....

 

Double checked tonight and you two are right about the wiring, it's how you described.

Both coils are good

Fuel supply good

Must be the TCI unit

 

Don't rule out the possibility that some of your new plugs might be faulty - I've come across this a few times.

Also - how have you checked your coils? Have you swapped them around to see if the problem follows the coil?

Best to do the cheapest / simplest checks first before you buy another TCU.

 

I used a multimeter to come to my conclusion

Same ohm reading with both coils

But when checking the voltage of the wires going to each coil,

The coil with the cylinders firing properly read 12V

The coil with the cylinders not firing read 0V

So the one coil isn't getting any power

 

Either the pickup coil is bad for that bank or the TCI is hosed. Ohm out the pickup coils and pull the cover off of the TCI to see if any of the solder leads are cracked.

 

If this is the same basic ignition system as in the SECA 750, then the problem is probably not the TCI unit.

The 12V to the coils doesn't come from the TCI unit, it comes from the battery through the ignition fuse. One fuse is shared for the two coils, so it can't be a bad fuse. The TCI unit grounds the other pin on the coils to charge them, and releases the ground to fire the coil. If the TCI unit was shorted (pulling the pin to ground all the time), it would quickly blow the fuse... so, again, it doesn't sound like the TCI unit is bad, it sounds like the wiring going to the 0V coil is bad.

Jumper the 12V side of the non-working coil (through a 5A fuse) to battery plus and see whether you start getting spark.

Paul

 

One of his ignition pick-up coils could be bad, or a pinched wire lead from it to the TCI.............

 

Well after double checking everything again tonight it's the coil. Good news in my opinion because it beats buying a different TCI

Had one from the parts bike that worked, only I found it was for the cylinders 2&3 thus the wires are too short

 

I'm pretty sure I read, in another thread, that chacal has a tool to make splices on factory coils to add new wire.

You should check with him to confirm that thought

 

Folks, I don't think there's any saving the OEM Coils from the ravages of Time.
As they turn 25 years old ... many start giving-up the ghost.

Getting-on with them as they get old is a crap shoot.
They might be OK for another season or two; but I think we should all be getting ready to bid farewell to these OEM Coils just like many of us have already bid farewell to the Fuse Panels.

With that in mind, buying Coils off eBay that came off a bike as old as ours are might not be the wisest thing to do.
They are getting as old as the one we got.

 

Hi Rick, how about posting a piece about identifying coil problems, as we know they can be very fickle things.

 

Most of the Coil Death episodes all share the same complaint from the Owner who had one go South.

"My Bike was running fine; now it's missing and backfiring"

I don't even know what it is that breaks-down, yet.
The external connections, the Coil or the Spark Plug Wires.
Just that, now after a couple of decades or more, there is a spike in the occurrences of people having a Coil go out on them.

I think what I might do is slice one open and look inside for anything that looks funny.

Any guesses of what I might find in there?

 

The difficulty with identifying "coil problems" is that the symptoms caused by a bad coil(s) can also be, in many instances, the same as those caused by carb problems.

Except in rather exceptional circumstances or conditions (i.e. only runs poorly when it's wet, or very damp), coils are pretty simple, durable little beasts.

As long as their primary and secondary resistance readings are in spec:

Ignition Coils:

For all models except XJ700's and XJ900RK:

Primary (input): 2.5 ohms +/- 10%
= 2.25 ohms - 2.75 ohms

Secondary (output): 11K ohms +/- 20%
= 8,800 ohms - 13,200 ohms

For all XJ700 and XJ900RK models:

Primary (input): 2.7 ohms +/- 10%
= 2.43 ohms - 2.97 ohms

Secondary (output): 12K ohms +/- 20% (XJ700)
= 9,600 ohms - 14,400 ohms

Secondary (output): 13.2K ohms +/- 20% (XJ900RK)
= 10,560 ohms - 15,840 ohms


Then they are going to be happy (as long as they are also receiving close to 12V input on the primary side).

All of the above reisistance readings are taken at 68-degrees Farenheit, and on the secondary side, WITHOUT the spark plug caps installed.

It's also a wise and prudent action to check the resistance of each spark plug cap boot. They should be either 5K ohms or 10K ohms, depending on which model you have. And except for instances of extreme derivations from specifications, more important is the "sameness" of readings across different caps (much like with cylinder compression readings: the actual reading is not that important, but the variance between cylinders is).

Of course, you should make sure that whatever ohmeter that you are using is calibrated correctly before use. On analog style multimeters, the different resistance range setting do require a re-calibration of the meter to a zero reading.

 

Rick; What you'll find in there is exactly what the name implies, a coil of wire (probably quite a lot) wound into a cylinder with an iron bar in the middle. Probably "potted" into the plastic the way the plug wires are, or it could be filled with some sort of horrible, smelly toxic PCB-laden electronics component guts GOOP like a capacitor, but there will still be a coil of wire around a core. I'd wear safety glasses and rubber gloves, and use a bandsaw to cut it at an angle like a salami. Let us know what you find, please. I have my own theories as to what goes wrong, mostly due to my experiences with failed Lucas coils which are not made quite the same. It would be VERY interesting to carefully cut apart a failed one.

 

I don't think I'm going to go splitting-open a Coil now that I know that there's PCB's inside.
I've had enough exposure to PCB's.
If they're encapsulated in the Coil; they're staying there.
I'm not helping them escape.

 

I think the component most likely to break down would be the secondary winding.

 

SQLGuy had it right on the money. If you supply a coil with battery voltage -- with everything else hooked up -- and you break the circuit on the ground side, the ignition coil's magnetic field will collapse which will induce a current in the secondary winding. This is where the HV spark comes from.

A quick test for a coil (CAUTION: Risk of shock! Use caution.):

• Hook 12 volts to the coil's '+' terminal.
• Hook a test lead or coil wire from the coil's secondary side to a spark plug or spark gap tester gapped to whatever is specified for the ignition circuit you're testing.
• Ground the spark plug or spark gap tester to the battery's '-' terminal.
• Momentarily ground the coil by hooking a test lead from the battery's '-' terminal to the ignition coil's '-' terminal.

When you break the ground connection, a spark should jump the gap on your spark plug or spark gap tester.

I usually repeat this test several dozen times to build some heat in the coil to make sure it fires when it heats up.

(Here's the tool I use at work to test customer's coils.)

 

Well it's official, my one coil is dead.

Tested using a spare coil I had laying around (one meant for 2&3 so the plug wires are too short unfortunately) but i was able to get spark on the plugs.

So now my question is

Is there a way to lengthen/replace the wires? (It looks to be just one assembly)

Or I do have a spare 1&4 coil but the ends that attach to the plugs are broken off, if there a way to replace the ends?

 

Sure, they just unscrew from the wires.

 

Coil Surgery is possible.
It takes removing some material from the Coil.

Once you get the old wire pulled-out; you have to secure the new wire's end to the "Nail Head" within the Coil.
I soldered the end of a wound, wire-core, spark plug wire to the point exposed when the old wire is removed.

My write-up and photographs can be found here:

http://xjbikes.com/Forums/viewtopic/t=1 ... rgery.html