here's a strange spark issue

[cajun1957a]

I can kick till the cows come home and when i turn off the key, it pops into the pipe.  Oviously an ignition problem. 

randy

[cajun1957a]

I dont have a condenser on this bike.  The ignition is a Mallory Electronic set up.  It started perfect yesterday....today i kicked it over and nothing.  After a few kicks I let it sit thinking it was flooded.  The second i turn OFF the ignition it popped and rather loudly.  Must have been fuel in the pipes.  It will do this everytime.  I have another distributer I will try tomorrow.  Coil, wires, plugs all new and worked yesterday without a hitch. 

If the new distributor doesnt solve it i will post it on youtube and you will see what it does.....

randy

[wreck74]

take the plugs out, hook'em up to check for spark. verify that you have spark, then turn your key (ignition switch) just put pressure on it, not to where the switch clicks, then you went to far. one way or the other then check for spark again. just another way of checking the ignition switch. cause thats what it sounds like.

[cajun1957a]

Well its not the ignition switch.  I swapped it out and the coil as well.  When i turn off the ignition switch, both spark plugs fire.

randy

[olpigiron]

             I Had A Problem Like That, I'd Kick Kick Kick Kick Kick, Then Get A Backfire and A Pop.
                                    I'd Kick For An Hour and It Would Not Start.
                               I Checked All The Electrical Stuff, All Checked OK.
       Pulled Carburetor (Bendix), And Found a Small Crack In The O-ring in The Main Jet Assembly Tube,
                      Replaced O-Ring, Put Carb. Back On, Two Kicks and It Fired Right-Up!!!!
                                                  Just Something to Look At.

[jmanjeff]

It sounds like you may  have a bad Ignition  Unit.   

[cajun1957a]

This is a strange one indeed.  I just happen to have a brand new electonic distributor still in the box.  Same thing no difference.  So its not the ignition switch, coil, distributor.  The only thing left is the volt reg. and the wiring.  Strangest thing i ever seen. 

randy

[Lew]

Is there proper voltage at the coil + with the ignition switch on?

Lew

[cajun1957a]

The fella that did the original wiring of the bike just left.  We verified the ignition switch, swapped out the coil, tested for shorts and continuity on all the wires and even plugged in a new distributor and yet...the minute you turn the key to off both plugs spark.  There is not spark when kicking it over in the on position.  All lights work as well when the key is turned to on.  My guess is it has to be the distributor some how yet i plugged another in and grounded it to the block (didnt R&R it).  It of course is new and I have a spare New one cuz the orignal shook itself apart once. 

His suggestion is to go to a points distributor.  I dont want to do that if I can help it.  I only got a partial automatic advance dist. and I got a ton invested in these two mallories.  If there is some none logical problem....I got it.

randy

[Lew]

Hook up a voltmeter to the coil positive terminal and turn on the ignition, verifing proper voltage there while attempting to start the bike.  Look for a significant drop in voltage while the coil is trying to fire.  Might be a bad connection feeding the coil that would be displaying proper voltage until an electrical load is placed on it and is then lost due to high resistance.  Is there a handlebar kill switch?  If so, might jumper it out, it could be bad causing a loss in voltage to the coil.  If no issue with lost voltage at the coil primary then it's in the e box.

Lew

[cajun1957a]

I dont know if I have explained the issue properly.  Some specs on the bike first.  1965 XLH 900.  Kicker only.  Mallory Electronic distributor A576.  S&S Super E.  2.9 ohm Coil.

When this first happend was on Sunday May 17.  I went to kick it over and nothing happened....I kicked several times without success.  When i gave up, i turn off the key and a popping sound was heard inside the engine.   I kicked it again and the same thing happened.  I pulled out the plugs, turned on the key, kicked it over and noticed no spark on either plugs.  I replace them with out success.  Again immediately upon turning the key off I heard a popping.  Monday, i removed the plugs, let them dangle on the block and kicked it over to see if I had spark.  Nothing and when i turned off the key, they both sparked.  I can do this ever time.  The minute the key is turned to off, both plugs spark.

I began to systematically swapp out components in the electrical system as per some suggestions here.  First, I replaced the ignition switch.  Turned on the key, no spark when kicking, turned off the key both plugs arc to the block.  Then I swapped out the coil and the same thing happened.  The only spark I get is when the key is turned to off and immediately when the key clicks off, the plugs arc.  I then swapped out the Mallory electronic distributor.  I have a spare and plugged it in.  I didnt have to remove it because they plug on it is long enough to hook another up.   I did that and grounded it to the block.  turned the key to off and again the plugs sparked when they was sent to the off position. 

The only thing I did not check was the voltage regulator, and as it doesnt seem to make sence how it could affect this issue, I am going to R&R it anyway.  I had just replaced it last week due to a none charging issue.  That is the only component in the system that I havent done.  All the wiring has been checked as well. 

I dont even have to kick it over to know the system will not work, I only have to pull the plugs, ground them to the block and turn the ignition key to "off", and if I get a spark on both, something is wrong.  I wonder if anyone else has had such a situation.   There are no condensors etc that a stock bike would have to check given the electronic ignition system.

I am just beginning to get into building old ironheads, that is why I have many extra parts available to test and swapp out.



Thanks...

randy

[rigidthumper]

Path is: ground through points ( or hall cell) to 1 leg of coil, through windings to 2nd leg of coil, to a power source ( ign switch). As long as the coil has primary circuit continuity, with good power/ground, it will charge. If the circuit is broken (key off, points open, etc) the primary circuit stops charging,the current field breaks down,  and the secondary circuit reacts by discharging it's stepped up voltage to ground, through the plugs. If you don't have a good ground/ground control (provided to the coil via the Mallory unit) the system cannot charge/discharge correctly. Verify grounds for the whole system.
BTW, if you switch to points, go to a 5 Ω coil.
HTH
Robin

[cajun1957a]

Tested the ground on the mallory and its fine.  I guess Im going to pull that distributor and if that dont work, Im out of answers.. 

[Lew]

My diagram shows the stoplight switch paralleled with the coil positive.  Possibly the switch is grounded.  Check it or remove the wire feeding it and see if things change.

Lew

[cajun1957a]

Success:

I replaced the distributor with the spare I had.  The plugs still fire when I shut the key off, but now runs.  Before it would not fire at all, only when turning off the key.  Lew your explaination of how the plugs discharge if a ground is not present to the elec dist. made all the sence in the world.  It appeard to do just that.  I complete redid the ground wire on the mallory ign. but it still sparks when the key goes off. 

Recent changes i did was to change the volt reg cuz it stopped charging.  The reason for the coil replacement is that the bike would buck and miss under moderate load.  I had assumed it was the coil.  It appears that the distributor is the culprit.  The new coil I put on is a 2.9 ohm coil and that is what Mallory said I should use with solid core wires.  I tested my original and it reads 5 ohms, which im told is to be used with points.  I sure hope this doesnt happen again, but at least i now know how this thing acts when it will run.  What do you think as far as coils.  The mallory is model A-576 http://www.malloryperformance.com/pdf/576.pdf 

Let me know what you think based on all this.   I know pistons, rings, valves, points, etc, but electrical and im lost.

randy

[IBARider]

Glad you got it fixed.  As far as firing when you shut off... that sounds normal to me. 

Think about it from the view of 'points'  The points are the ground side of coil.  With key on, the coil is hot at all times, when points close, the primary coil circuit is closed/complete and is ON.  This is when the secondary coil, (the part that fires your plugs) is charged up.  When those points open, (Primary coil circuit opens and off) the secondary coil discharges to plugs.  So... assume those points stay closed all the time, the secondary will not discharge/fire plugs.  When you shut off switch, you're basically doing the same thing as opening the points, the primary coil circuit is off and the secondary discharges, firing the plugs.  Don't ask me how that whole secondary induction thing works, I just know that's what it does... So... it sounds like your ignition was acting like points would if they stayed closed all the time.  Just turning your key on then off will fire the coil if the primary side is closed/complete.  electronic and points will do this

[saltcaveminer]

make sure the Mallory bat + goes to the coil + then to the ignition switch and begins at the battery.Salty

[Ironhead RON]

Read this one message and thought a bit. Then the possibility of the firing problem. "The Fire Triangle".
Three things needed for proper ignition. Heat, Oxygen and Fuel. 1) There has to be fuel to burn.
2) There must be Air to supply Oxygen. 3) There must be Heat (Ignition Temperature) to start, and continue
the combustion process. In your case There was Air (Residual) in the cylinder. There was a Heat Source
(Spark from the Plug) in the cylinder. And Fuel (Residual from a couple or so squirts). Remember the engine
had not started to burn it off.  Turn off the keyswitch and pop pop in the pipes.  Recheck your S & S "E" float
level and for sticking of the S&S controls. Would not take much to leak by in the carb to cause the problem.
The gasoline would tend to vaporize and make it easier to ignite. Also when had you gassed up and whose
gas and what grade ? Ethanol (Alcohol) still available in varying amts in some brands of gasoline. If it was old
gas dump it and put in fresh.