No spark/where to look

Rewired my bike based on the minimal wiring diagram posted up here. Everything seems to be in order, but I'm not getting spark. I out new plugs in, and the bike tries to start, but only gets a little zap when I let off the start button. Other than that, at best a weak intermittent spark or no spark at all while trying to start. It's probably in my wiring somewhere, but if anybody can give me advice on where to start tracing back that would be great.

Thanks.

 

Is your battery at full strength? Even if it seems to be turning the engine over normally, there has to be enough juice left over to deliver good starting spark.

 

I just put a new gel battery in it, and so I know it's low, bumpy I was jumping it off my car battery and it had plenty of juice -- just weak spark. It ran fine a week ago prior to rewiring.

I've got the new battery on the battery tender right now so hopefully you're right and it fires right up tomorrow, but after jumping from the car and not seeing much spark I don't have high hopes...

 

You can go through alot of trouble-shooting to find a No-Start problem.

If you KNOW the Bike is SOUND and WORTHY of an Ignition Upgrade; we will all soon need to do one.

1) Fuse Panel -- ALL XJ Bikes with ORIG Fuse Panels need this Mod.
2) Coils & Wires
a) Complete NEW Coils w/ Wires and Plug Caps.
::: DYNA Coils and Performance Wires.
>> This Mod is made much easier WITH Optional Custom-fitting Mounting Brackets.
3) Black Box -- Overhaul. New Transistors and Critical Circuit Boards Installed and Re-soldered.
4) Switches and Relays -- Overhauled, Cleaned or R&R'ed.

Other options:

"Coil Surgery" ==> ( Search )

 

1.) Fuse panel has been replaced
4.) The only switches and relays on the bike are an on/off switch, and a push-button to start. Both of which are brand new.
3.) I just replaced the Igniter box with a used one, and I plugged it into the roommate's bike to make sure it's good. Started right up.

So that only leaves 2 -- is it really possible that my coils were fine a week or two ago, I rewired the bike, and now they're shot? Seems to me like there's probably something else going on (probably a bad connection in the new wiring somewhere, but I was hoping for some leads on where to start looking...)

 

does the new switch have to be grounded to the handlebars?

 

The switch shouldn't need a ground at all according to the wiring diagram. The start button is grounded. I have it mounted on the frame under the tank and it's grounded to the frame an inch or so away via a screw.

 

You didn't jump it off a car, did you? A car battery will toast your system, hope you jumped it off a bike...

 

Strange comment. What makes you say that - the supply voltage should be the same.

 

Give the Spark Plug Wires a close inspection.
The very way that the Plug Caps are affixed to the Plug Wires compromises the connection over time.

The "Screw-on End" where the Plug Cap is fitted to the Plug Wire ::> Cuts <:: into the Plug Wire Core.
After a good deal of Plug Changing and Plug Cap tightening, ... the Plug Wire Core gets "Chopped-up".

Trim them back a bit ONLY if you have enough slack.
If not, ...
INSERT as much Solid Copper Wire ... Up into the Plug Wire that will go.
Give the Plug Cap a New Core to make contact with.

The paper-wrapped Neutral Wire from Household NM-Cable does the trick, very nicely.
Sand the tip to a dull point.
Smear it with Solder Flux or Petroleum Jelly.
Push as much as you can up the center of the Plug Wire.

Grab as much spark as those Coils will put-out.

 

This is the CLASSIC symptom of a weak battery.

It's possible for the battery to spin the motor quite vigorously but then have no current available to fire the ignition. The tip-off is the firing as soon as you let off the starter button; when you do that it takes the starter load off the battery and the ignition fires.

 

More info: still won't start but I haven't had a chance to work on anything. I replaced the battery with a tru-gel and it's been hooked up to the bike with a battery tender attached for a week, and yet it barely has enough juice to turn the starter over more than a turn or two.

Is there a short somewhere causing the battery to lose charge/not charge? Or is the battery no good? Or will a tru-gel not work on these bikes?

 

Have you tried push starting her? Perhaps it isn't the ignition circuit but the starter motor circuit with a short / bad connection

 

I'm going to test the coils and take a look at the plug wires this weekend. Sunday will be my first day off in a couple weeks, so I haven't gotten a chance to do anything about it yet.

I doubt it's the starter motor though... it turns over just fine. I put a new (non-gel) battery that was fully charged and it still only sparks intermittently, and usually only after I let off the start button. I'm not sure how push-starting would give different results spark-wise than using the ignition?

 

What you describe here is a symptom of excess current being drawn. Assuming your coils are good, this is suggestive of a problem with the starter. The motor may need new brushes, or there may be a loose or shorted wire somewhere in your circuit.

Since you get spark mostly after you let go of the starter button (in other words when you are NOT drawing current for the starter motor, but while the engine is still spinning from momentum), then this indicates that something changed and gave your coils the power needed to generate a spark. You let off the starter button and that opened the starter motor circuit.

By push starting the bike you eliminate the entire starter motor circuit for diagnostic purposes. Look at it this way:
1. Turn the engine over by external force by push starting (i.e. no starter motor circuit) and you get spark, bike fires right up. Probable diagnostic outcome: short/bad connection in starter motor circuit BECAUSE the bike stated fine without it.

2. Turn the engine over by external force by push starting (i.e. no starter motor circuit) and you get weak spark or no spark, the bike does not fire up, or dies out shortly after. Diagnostic result: further investigation needed.

Either way, it would be wise to check the primary and secondary resistance of your coils, plug caps, check to be sure you have the correct plugs installed so you are producing the correct resistance in the ignition circuit. If you find numbers out of spec, chances are your plugs/coils/wires need service or replacement. You may find that you fix this and your bike fires right up - problem solved.

 

Actually that symptom (firing when you let go of the button) is usually just a flat battery.

I would take the Tru-Gel unit to the local auto parts and have it tested for load capacity once you believe it to be fully charged.

If it's fine then I would be looking into why the starter might be drawing too much.

 

Thanks for clarifying that, Fitz. I guess since Redneck told us he's got a new battery and noted that he had been charging it I accidentally ruled that out.

 

Greg from london:

http://forum.motorcycle-usa.com/default ... 8&m=430724

Good read for anyone who considers jumping motorcycles from cars. Short story: it can be done, but the car should be turned OFF. Great laymen opinions from both side, experience, and then an expert weighs in with lots of useful info.

 

That's a big sign of a low battery. I don't care if the battery is brand new out of the box and doesn't need charging, either. If you have that issue, you've probably got a low battery. If it IS new, you got one bad one.......been there, too.

Dave F

 

I should have specified: I charged the new battery myself, and tested it and it is most definitely fully charged but getting a weak/intermittent spark. I have a few hours off tomorrow -- I'll give the push start a go and if that's a no-go I'll get to testing the coils. Thanks for the help!

 

Batteries wont get "Charged" ... by being hooked-up to a Tender.

The Tender KEEPS the Battery from losing its charge.
750mA keeps the Battery from going Dead on you.

To CHARGE the Battery its best to have a Charger capable of sustaining 2-Amps or more.
The TENDER is providing less than 3/4ths of an Amp. Some have timers.

 

Weird. My battery tender package clearly says it'll charge then switch to float. Meh.

Either way. Battery charged via actual battery charger. Push start. No dice. Lots of backfiring just like when I try to start off the battery. I'm getting to work checking al, the connections and the coils now.

 

+1 for getting the battery checked out... though a trickle charger should recharge a flat battery easily in a week. Backfire is symptomatic of it at least trying to start - maybe flooding. Try some new plugs.

 

@ Fintip

So we agree then - you can jump a bike off any vehicle battery that's 12volt. If the engine is running, then you might damage the jumped vehicle electrics. That is dependent on how fragile the systems are. I has a Saab that would not start once and jumped from a smaller vehicle which had the engine running and blew the ignition coils.

On most bikes you can jump with impunity from a running vehicle (car, bike, bus), but I won't guarantee you which one. You can jump from ANY battery that's big enough though...

 

Most Jump Starting Guides for Motorcycles include the following passage:

The procedure to jump start a motorcycle from a car is the same as it is for jump starting it from another motorcycle.

• A car battery has far more more amperage, and the charging system for a car is much more powerful than that of a motorcycle.
• When jump starting a motorcycle from a car, DO NOT START THE CAR'S MOTOR because the extra power from the charging system could possibly destroy the motorcycle's charging system and could cause a fire.
• The car battery should have enough power to start the motorcycle without the car's motor running.

 

Good to know abut the car battery. I put a fully charged and tested battery in, and still only get spark when I hit the start button and when I let off. One quick hit for each. No spark while I'm holding the start button and the bike is cranking.

I checked the connection to the starter motor and it's solid. One wire straight from the motor to the solenoid. Not much room for error there, but I double checked all the connections anyway and rhey're solid.

Only thing I can think of at this point is the coils. Maybe jumping off my car frieD them? I only had a few minutes with the bike yesterday and didn't get much time to do anything but I'll try to test the coils this weekend.

 

If you have WEAK Spark; it could be related to the Spark Plug WIRES.

The Plug Caps SCREW on with a SHARP Self-tapping Thread.
After many tight-checks and wire-pulls, ... the ENDS get "Chewed-up".

1) Trim back the Wires 10~15mm and replace Plug Caps.

2) If theres not enough slack, ... shove a Solid Copper Wire right up the Center of the Plug Wire as far as it will go. Trim. Replace Caps..

 

If the battery is fully charged, has been tested and known to be good and you're still only getting spark when you LET GO of the button, something is drawing excessive current and not leaving enough for the ignition.

If you're confident in the condition of the large leads to/from the battery, the solenoid connections and ground straps, etc., then the problem is likely the solenoid, or the starter itself. It's not unheard of for a gummy starter to need an excessive amount of current to work apparently quite well without you realizing what a "juice hog" it is.