Very Weak Spark

I recently acquired an '81 Maxim in lue of some money owed too me. It used to run great and I have heard it run in the past. Recently, the old owner forgot the sideside when getting gas, and it toppled against a gas pump. It refused to start after that, unless it was bumped started. Then it'd run a few minutes then quit. Anyway, now that I have the bike I am in the process of refurbishing it. I finally got juice through all the wires, but there seems to be an issue with the plugs, coils or the voltage /amperage going into and out of the coils.There is weak spark coming out of the plugs that almost needs a magnifying glass to see. So....what I'd like to know is....what is the average line voltage and amperage needed, for the wires going into and out of the CDI, the wires going into the colis, and the voltage/amperage coming out of the coils....to get a decent spark. I have very limited funds, as I am on a medical disability...but want to get this bike running again as a winter project so I can sell it. I live on the east side of Seattle, incase their are any charity case "fixer uppers" who can help. Thanks....Jim

 

One thing to note is that the spark is dependant on the available voltage and current from the battery... unless you push start it and then the charging voltage and current from the generation circuit comes into play.

Bad battery or under-charged battery equals bad spark out of the gate.

A good car/truck battery via jumper cables is a good way to check this and eliminate this condition as a test.

When running the voltage supplied should be 13V~13.8V(battery connected) volts at a charging RPM level for most 12V systems.

 

Ok, first thing is first, check the battery. If you don't have 12.5 v, charge it or replace it. On these maxims, if you don't have a sufficiently charged battery, the coil is the first thing to get taken out of the equation, even if the engine is turning.

Second, it sounds like the p.o. either disconnected the Side stand switch which is going to be a green connection in the head light bucket, OR, the side stand is gooped and not returning to it's position.

Go and get new plug caps, AND get new plugs. All four of them. You'd be amazed at the amount of corrosion that occurs in those caps and for 4-5 bucks apiece, will make a world of difference.

Another thing, take 1/8" of wire off the coil wire if you have a bit of room to play with.

Clean and Dilectric grease the coil connections to the harness

Clean and Dilectric grease the side stand relay (blue and black near the rectifier)

 

DO NOT under any circumstances have the car running when you jump it...you WILL fry something on the bike.

The battery should register at about 14.2 v at around 3500 rpms...or in the range the other poster said. Start with a new battery. If that doesn't correct the voltage issue, you are in for probably a stator.

 

Don't forget to check the brushes, a common problem. The "brushes" are graphite sticks in the alternator that are designed to wear down and be replaced. Take the alternator cover off and you will see them, you should be able to see a notch in them. If you don't see a notch, it's because they have been worn down too far.

 

having the car running does absolutely nothing to the bike itself. the alternator doesn't PUSH to the bike. the bike simply PULLS what it needs.

the battery however, could get ruined.

the spark produces between 5k - 7k volts. not very strong so don't be expecting any fat white sparks like a car can produce.

 

If you are running 'R' plugs & caps, replace them with non resistance.

 

Aside from a great many issues which would hamper the strength of Spark due to Ignition and Wiring, ...

You also get ... "Seasonal"

As ambient temperatures decline; so does the willingness of the XJ-Bike to Start.
Keeping the Battery up helps a lot.
But, getting a Dead Cold XJ-Bike started on a chilly day requires patience.

One thing you can do, which I find helps-out big-time is:
Running a length of Windshield Washer Hose from the Side-rail down into the Fresh Air Inlet of the Air Box.
Shoot a few blasts of Starting Fluid or Carb Cleaner into the Hose before firing that baby up.

Also:

Refurbishing the Core.
The screw-on Plug Caps shred the Spark Plug Core fibers and reduce the charge reaching the Plug.
Restore the wallop you need.
Strip a length of NM Cable to the bare copper wire.
Burnish the end so it won't hang-up when shoved into the end of a Spark Plug Wire. Force the Wire up the center as far as possible.
Double Heat Shrink the end.
Screw-on the Plug Cap and tighten good.

 

'81 Maxim WHAT? 550, 650, 750?

The plug caps screw onto/into the wires. Unscrew the caps, lop about 1/4" off the wire and screw the caps back on being sure not to overtighten.

Look inside the cap itself and if yours are the style with screwdriver slots on each side of where the plug tip plugs in, be sure the "core" is tight in the cap. (Not all plug caps have screw-in cores from what I can tell.)

The above advice in regard to the alternator and battery is very good; if we knew more about the bike (what is it, how many miles, some better history) we might be able to help even more.

For instance, if it's a 550, I could send you the charging system diagnostic page, or the ignition diagnostic page, from the factory manual.

 

Snowy, I have to respectfully disagree. I fried an entire electrical system on a xj700 with the car running. I would not recommend a vehicle running while trying to jump a bike.

If the OP does it, I say good luck and be forewarned of the consequences observed by others.

 

It is true, having the supply alternator off during a jumpstart will reduce the voltage to no more than the battery can produce. With a good regulator, it really shouldn't matter, but a car battery by itself should be plenty of juice to jump a bike that is known to run and would be the safer choice if you, say, left the "park" light on. Not that I've ever done that...ahem....

In short, you are both right...it shouldn't matter, but it could matter.

But there are plenty of tests to troubleshoot an ignition problem. Coil tests, CDI tests, battery tests, alternator tests, replacement spark plug test...but "looking-at-the-spark-test" isn't one of them. Very unreliable.

 

i would say he had the jumper cables crossed. that's the only way to fry anything. or his problem was already burning out.

i've jumped my motorcycles many times without any problems. sometimes with a running car. my suzuki had the original battery so i had the car running for that one. becuase the battery was already no good. i needed all the cranking power i could get. the bike cranked over but never did fire up untill the battery was replaced.

i've burned out a regulator, and a computer. both on cars. but it was dark. no flashlight. cables were teh same color and the batteries were dirty makeing it very hard to determine polarity. and i'm not talking about MY car that was doing the jumping.

 

I will respectfully disagree. This is contingent upon the condition of the battery. The instant you connect the non-running bike (the load) to the running vehicle (the generator), you will introduce a HUGE current spike (referred to as current in-rush in the business) if the battery is low or dead. On a fully charged battery, there isn't the lack of capacity so it won't pull gobs of current. Best practice is not to connect a running car to a dead battery, hydrogen is explosive in the presense of sparks (hint: check out the Hindenburg tragedy).

You are correct, refer to the explaination above. The alternator is designed to output higher current based upon demand.

Again, this is conditional based upon the state of the battery. A dead battery is asking for trouble. Similar to the problems experienced by our friend, mcrwt644.

A spark does not produce voltage, voltage will produce a spark. A bike's system can produce adequate spark provided the coil receives sufficient voltage and the rest of the ignition system is sound. A white spark is normal on a stock bike system in good repair.

You can do this to ease a weak coil along for a bit more but this is a band-aid. You need the resistance to generate a healthy spark. Mind you, it needs to be a specific amount and too much will kill the spark (as the "green" crud/corrosion in the spark plug boots will bear witness to).

 

The seasons change and the Jumper Cables come-out of storage.

Every year,... AAA and the Society To Prevent Blindness join forces and send-out a Brochure to AAA Members that should be in the Glove-box of everyone's car or truck.

The truth is, ... People have become far too cavalier about hooking-up Jumper Cables from their vehicles to others with dead batteries.
We act like there's no risk. When an average of 6,000 People sustain burns or serious eye injuries, ... every year.

You need to act like your a Bomb Squad Technician; and follow procedure.
Don't let the Energizer Bunny lull you into a false sense of security.

The Battery you hook-up "HOT" Jumper Cables too might be gassing.
Hydrogen.
Needing only the slightest spark to ignite the Hydrogen Gas and blow up.

Follow procedure:
"AAA Safety Procedure"

1. Connect one end of the RED jumper cable to the POSITIVE (+) post on the DEAD Battery. The POSITIVE battery post may be slightly larger than the NEGATIVE post, and will be marked with a PLUS (+) sign. There may also be a RED plastic protective cover over the positive battery post.

2. Connect the other end of the RED jumper cable to the POSITIVE (+) post on the GOOD Battery.

3. Connect one end of the BLACK jumper cable to the NEGATIVE (-) post on the GOOD battery.

4. Connect the other end of the BLACK jumper cable to a heavy metal ground on the Engine or Frame of the vehicle with the DEAD battery.

DO NOT make the final jumper connection to the NEGATIVE (-) post on the DEAD Battery itself!!!

<>+<>+<>+<>+<>

Because:
It usually sparks and may ignite hydrogen fumes in the dead battery causing it to explode.

 

that's SUPPOSED to be the procedure.

but does anyone actually follow it. LOL.

todays cars though are so covered in plastic. you're going to have a hard time finding a good ground connection. specially them hybrid cars.

 

I do, after having a battery explode right in my face covering my face and eyes instantly with battery acid! I was working on replacing a waterpump in a car and listening to the radio all day as I worked. Upon completion, I had to jump the car to get it running and as I di, the battery exploded right in my face. It sounded exactly like my 12 guage shotgun. Thankfully, I had a gallon jug of clear water right next to me that I had for topping up the radiator, I grabbed it and poured in into my eyes within a second of the explosion, then as it ran out I ran inside and shoved my whole head under the kitchen faucet flushing them further. I kept this up as my GF called the hospital, after 20 minutes or so my naighbor took me there on his motorcycle as the car still wasn't running. The hospital was less then a mile from my apt at the time. They continued the flushing for another 1/2 hour and the Dr told me that although he could see burns on my lens and cornia, I was very, very lucky.

Needless to say this is why I'm very careful now...hopefully other won't have to learn the hard way as I did. A few days later when my GF washed my clothes, my shirt lost almost all the fabric from the 3rd button up.....the evidence of the battry acid.

Jeff

 

Everyone always wonders why my beemer battery is in the trunk, with connections under the hood. Do any other manufacturers have the good sense to make their batterys "explosive proof" this way?

 

there was a car that had the battery located under the passenger seat. don't remember what it was but i think it was a VW of some model. or audi.

and i think the BUG had the battery in the front trunk. instead of in the back with the engine.

 

The venerable Beatle had the battery box under the rear passenger seat amigo. Lousy location as if you had an overweight passenger or too tall a battery, you would short the battery. Seen my share of toasted Beatles thanks to this, old fuel lines and loose fan belts.
Time does not change things much, my '08 Saturn Outlook (that I LOVE) has the battery in the passenger compartment, just in front of the right side 2nd row seat.
For additional reading on ignition I can recommend two very excellent books. First, Dr. Jacobs (of Jacobs Ignition) "The Doctor's Step by Step Guide to Optimizing Your Ignition" is increadibly informative and goes into the whys and whats of the modern ignition system. The other is the "How To Keep Your VW Alive For The Complete Idiot" by John Muir (RIP) Publications. It shows the system in the simplest terms possible with easy to understand commentary.
Both are available and worth every penny.

 

sooo, enough of the cars, did the OP make any progress?

 

Thanks 644, forgot to focus...