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Old 01-27-2009, 12:29 PM   #1
dorkpunch OP
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Honda XL: A How to- Trouble shooting Spark Issues

Okay. There have been several people with spark problems on their XL's, so here is a basic trouble shooting guide.

Start with the wiring diagram HERE: http://www.oldrice.com/images/XL250W...pt#259,4,Slide

This is a very nice powerpoint wiring diagram that breaks the entire system down to its various catergories. Keep in mind the XL has THREE different charging systems: One for the headlight, one for the ignition, and one for the Battery and Accessories.

You will also need either a test light, or a volt meter. Heres my test light- a real cheap one that came with some set of tools. Works great!





Step 1.

Eliminate the stupid stuff. NO, the XL DOES NOT NEED A BATTERY TO RUN. Have you tried a BRAND NEW PLUG? Unplug the key switch and ignition switch. The bike will run without them, but if the key switch is unplugged, none of the lights will work.

Location of the key switch plug:



The kill switch is a bit harder, you'll have to trace it either to inside of the headlight bucket or to a bundle of wires above the engine.

Did that solve your problem?

No?

Step 2.

The only wire you need to worry about is the black with white stripe (B/W). It goes from the stator, splits and goes to the coil and the points. It also goes to the kill switch and the key switch, but you should have already tried unplugging both the key switch and kill switch to rule them out.

Unplugging the switches didnt get you any spark though, so: Get a test light and plug it in between the B/W wire coming out of the stator and ground. Kick 'er over. If it lights up, you've got power. If not, you have a problem with your stator. If thats the case, you might want to check out the other systems on the stator and see if they are working or not as well.

Pic of the main plug coming out of the stator:



Test light plugged in- you'll notice I plugged the light into the little pigtail coming out. No idea what the pigtail is for, but it was easier than trying to stuff the light in the square blade slot...



Step 3

We've got power coming out of the stator. Now what?

Unplug the coil from this Y:



Plug the light up in to the connection and ground. The light should flash on and off (on when the points are closed, off when the points are open).

IF: the light is on but doesnt flash: You have a continuos ground, and the points are somehow being by-passed. Maybe that teeny wire that hooks to the points?

IF: You get no light, there is no ground (or you forgot to unplug the coil). Points backing plate may be corroded, points not closing all the way, dirty or burned points, bad wire? Try cleaning the points with an extreemly fine grit of sandpaper, or some rough paper (ie- buisness card). Pry them open, insert the paper, let them close, and work the paper back and forth. You may have to repeat this proccess a few times using different spots on the paper to get them clean.

Points and backing plate- note the wire going to the points. Check it for wear. If there is any chaffing and it is showing bare wire, FIX IT!



Step 4.

Assuming the light worked okay on the points, the only thing left is a coil. I kid you not, the test procedure in the manual is, "lay the plug on the head and kick. If you've got spark, the coil is good. If not, get a new coil". Kinda lame, I know... Almost any of the '70s Honda Singles coils will work, so you can try hooking up a different on and see if it gets you spark.

Coil:



Hope this helped.

One other picture for you all. This is the points advance mechanism, located behind the points plate. It can get stiff over time and can affect how well your engine runs. Something to keep in mind...



ALSO- here is a related thread that has some good info: http://www.advrider.com/forums/showt...46#post8926046


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dorkpunch screwed with this post 01-27-2009 at 08:21 PM
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Old 01-27-2009, 02:53 PM   #2
Ernest T
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I'm hoping I don't need this thread when I put the engine back in the bike!
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Old 01-27-2009, 08:17 PM   #3
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Okay, added a bunch of pics and tried out my own test procedure... Changed the How-to so it should work for y'all now.
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Old 06-05-2011, 05:42 PM   #4
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Nice Timely thread for me. I just dug my 1974 Xl175 out of the basement at long last and seem to be getting either no spark or weak spark.

I can't see a spark when the plug is laid on the head and the bike is kicked...but I did get shocked when I grabbed the plug? It didn't hurt that bad so whatever.

I just can't see spark no matter what........

Anyway - using this handy thread I will see what comes of it.

Thanks for putting in the work!
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Old 06-05-2011, 07:47 PM   #5
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Hey, this reminds me... a new trick I've learned that seems to work for testing the condenser. While your kicking the bike over drag the sparkplug across the fins or jiggle it back and forth. If you get an intermittent spark, either the points or condenser are bad. The theory behind this totally scientific test is that the coil stores energy which is discharged when an electric field collapses. That collapsing field is somehow generated and timed by the points. When you jiggle the plug, you are collapsing the field manually and will get a nice big fat blue spark, but only every now and then and only when the plug is being jiggled. I've done this to THREE different bikes now, and if I can get this situation, replacing the points and condenser has fixed the spark issue. Weird, I know... but it seems to work.
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Old 06-05-2011, 08:51 PM   #6
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Nicely done Dorkpunch.
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Old 06-08-2011, 07:17 PM   #7
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It runs!

Got some new points and a plug cap in the mail and it runs.

Now to figure out timing....
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Old 06-08-2011, 09:34 PM   #8
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IIRC, using the F mark on the flywheel (NOT THE T!!!!), the points should just be starting to open when the F is at the mark as you spin the engine the direction it runs.
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Old 05-07-2013, 06:37 PM   #9
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Sorry to bring an old trphread back to life, but I have just started a restoration project and have run into an issue with the spark.

I'm working on just getting spark so I have everything unnecessary disconnected (key switch, kill switch, batter) so I'm running from the magneto -> points -> coil -> plug

I have followed the steps and have juice al the way up to the plug. Even checked everything with a multimeter.

To turn the engine over I am using a power drill to to the fly wheel.

The two questions I have:
1) when you say after testing the points the light should be blinking, how fast? It is nice and bright but doesn't seem to be blinking with the point breaks.

2) should the stator be grounded? If I plug into the black/white wire, there is continuity from that to ground. Is that right?.

Thanks everyone!!
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Old 05-09-2013, 08:37 PM   #10
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Hard to say what the blinking speed "should" be- depends on how fast you are spinning the engine. If you're using a hand drill, I'm guessing thats reallllyyyy slow... I'd be surprised if you're getting enough juice out of it to get a spark. Can you give it a good old fashioned kick while you watch the spark plug?

As for the ground on the mag, not sure. I'd have to check my book. Been way to long since I've played with any of my XL's.
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Old 10-17-2014, 12:46 PM   #11
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First off, dorkpunch, your threads have been a godsend for helping me repair these old beasts. Thanks so much for the time and effort!

Second, I'm currently chasing down a no-spark issue with a 76 XL350. It was running perfectly until I pulled some parts to change the fork seals and check on the spark plug. Reasoning would tell me that I jostled something loose or pulled a ground or something. I've chased EVERYTHING down, checked the stator for juice (all good), checked the points for juice (all good), all according to your method.

So that comes down to the coil right? No matter what I'm doing, I'm just not getting a spark from it. I even dropped $70 on a new OEM coil on eBay and having the same issues. I even screwed the spark plug in directly to the coil wire without the plug cap to bypass that variable. No spark. Any thoughts? Thanks so much man!
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Old 10-17-2014, 07:54 PM   #12
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Nice thread Dorkpunch. I might suggest a couple thoughts.

Cut to the chase, disconnect the magneto harness, run a wire from the magneto harness on the engine side (Black wire w white stripe) directly to the primary side of the coil, disconnect the existing wire. You've now bypassed the keyswitch and kill switch and all the junctions between.

Don't attempt to set the points gap by eye (the old, look and see if they're open at the F mark test). Take the time and gap the points properly, the difference in performance is notable. This is all the adjustment you'll get for ignition timing, so you'll want to set this gap accurately.

The magneto coil and ignition coil can be tested easily with an analogue volt ohm meter. They can also be tested with a Digital Multi Meter but the readings you receive will NOT match those in a manual. If you're going to ride vintage bikes, you'd best consider some vintage tools. Voltage at the primary side of the ignition coil (wrt chassis ground) should be aboot 6-8VDC (assuming 6V bike), tough to estimate with a test light. If it's lower than 6V either the magneto coil is weak or the condenser is done (or you're kicking it over very slowly).

A weak condenser will often cause spark to appear at the points or very weak spark at the plug. Roll the bike into an unlit garage kick it over and have a look.

theraymondguy screwed with this post 10-17-2014 at 08:01 PM
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Old 10-19-2014, 06:17 PM   #13
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Mightshocks- Need more info... What parts did you pull? I agree, something you did probably caused the problem, but there is a chance that something may have just crapped out.

The new coil- did it come with a new condenser already installed?

I spent several long phone calls talking to a guy that had a similar issue, and he assured me he had gone through all of the steps, yada, yada, yada, and was still having issues. We went over everything several times with no luck, and he finally found the issue to be the wire to the points in the wrong position so they were just grounding out. This was one of the first things I suggested he check, but it can be very confusing. If you messed with the points at all, thats where I would start.

I'm thinking though that if you pulled the front end apart to fix the fork seals, you may have messed up some wiring in the headlight bucket or ignition switch.

Have you tried unplugging the kill switch and key switch? Bike will run without them.

If all else fails, like TRG just mentioned, eliminate everything else. Figure out which wire from the stator powers the coil (should be black coming out of engine, but black / white stripe after the connector), run a new wire from it directly to the points AND the coil, and test for spark.

Is the coil bolted to the bike? It MUST be grounded to the frame / engine.

Wire from the coil to the condenser good?

Condenser new with the new coil? A test for the condenser- while kicking the bike over, drag the spark plug across the cooling fins. If you get an intermittent spark, you probably have a bad condenser.

Lets start with that for now, let me know how these things check out and we can see if there is anything else that comes to mind.
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Old 10-20-2014, 11:19 PM   #14
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Thanks to both of you guys! Fiiiiinally I found it.

Brand new coil with brand new condenser, brand new plug, new plug cap. Ignition unhooked, kill switch unhooked, getting nice bright light with the test light on the coil, getting a nice bright flashing light with the test light on the points, but NO spark, until...

I didn't even realize I was putting the points cover back on each time I was testing the spark plug. The o-ring that connects the white wire to the points was just barely hitting that cover, thus shorting everything out whenever I would put it back on.

I must've given the wire a jerk or something when I was hoisting and removing stuff. God what a headache.

Thanks for tipping me off on which things to check! I'd still be out there kicking the wall.
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