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Old 05-03-2015, 12:44 PM   #1
beansontoast OP
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Bluhduh chasing the spark XL350

Hi everyone, I've been going mad here.
Somehow lost the spark on my 1974 XL350.
I thought I knew how this all worked! I have followed Dorkpunches great old thread and been right through the oldrice timing instructions.
no result.
I have a test light illuminating from the magneto when I kick the bike over
( haven't measured the voltage but the light is coming on)
New points in place, set and gapped
New coil and condenser
New plug and HT lead
disconnected cut out and ignition switch
no spark, at least I cant see one, I have the plug clamped to the top fin with a vicegrip, should see and hear the spark click right?
I am missing something really simple-stupid here
In 2013 sound-dude08 asked Dorkpunch if the stator wire should be grounded to the bike. no answer.
I have the same question I have continuity between the black/white wire from the magneto and the bike, is this correct?
any help Very much appreciated
Thanks, Beans
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Old 05-03-2015, 06:27 PM   #2
XLRacer
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Is it a coil designed for the XL series? They used a 6 Volt AC coil, not the standard 12 Volt coil of today. I'd have to check the continuity on a motor I have sitting around and get back to you on that one. I'd also recommend hooking in the kill switch to ground the coil to kill the engine.

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Old 05-04-2015, 02:30 AM   #3
beansontoast OP
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chasing the spark

Hey Racer thanks for the reply
yes I've been carefully through that drawing
you are correct it is a 6 volt AC magneto with three primary coils - one for the spark, one for the lights and one to the rectifier for charging.
What I need to know is - when the black and white wire ( the one from the mag to the points/coil is disconnected is there continuity between that wire where it comes out of the mag and the bike?
otherwise I'm chasing my tail looking for a spark when I could have a bad generator
Thanks mate if you can help at all.
yes both the ignition switch and the kill switch ground that black and white wire to a green ground wire to shut down the bike . I have them both disconnected.
Thats why it doesn't make sense to me that the black and white wire should be grounded in the first place
Know what I mean jellybean?
Thank you very much for your help with this
all the best
Beans
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Old 05-04-2015, 09:03 AM   #4
XLRacer
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Ok, I'll check the mag on a spare motor I have laying around the shop tonight and let you know. However, looking at the diagram I posted, the coil in the stator for the ignition is connected to ground. The only "free floating" stator winding is for the rectifier. I would anticipate my test to show continuity to ground, maybe with a few ohms resistance.

Is the surface under the coil mount very clean and shiny? If not, your coil may not be grounding properly. I run a 4 wire setup on the racer. Black wire directly from stator, kill switch, coil and points.

Another thing to check is that your points are isolated. Disconnect them from the circuit and test for continuity to ground (I use the base plate) to be sure the power wire isn't grounded and shunting your voltage there. Make sure your points are open when you do this test.

I would also do a continuity test on grounding points. There is no ground wire, the engine grounds to the frame through the mounts. If those are rusty or corroded, you won't get spark. Test from the engine to the frame and make sure you have continuity. If you don't, clean up the engine mounts and bolts.

Lastly, make sure the connector from the stator isn't corroded. You should have continuity from the wire in the points all the way down to the black wire coming from the stator. You may be chasing a broken wire if this is an original harness.
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Old 05-04-2015, 12:46 PM   #5
beansontoast OP
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chasing the spark

Thank you Racer, the electrics are a bit tatty,
Forty years of Utah dirt
I think I have probably got a ground issue where i shouldn't have or not got one where I should have.
You are right that drawing shows the ignition stator clearly grounded at one end doesn't it.
I was looking for a 'quick fix'
I will go slowly through the wiring ( Its not the space shuttle after all, is it ) clean up, replace and tighten everything
Thanks mate for your help and interest

Beans
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Old 05-04-2015, 01:04 PM   #6
XLRacer
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If you want to bypass the original wiring, it can be done within a matter of minutes with a 16 gauge wire of good quality. Just use a bullet connector on the stator output and run it up to the coil and points. This would be a quick and dirty test of the factory wiring for issues.

I will still double check the stator continuity to ground, my own curiosity is peaked as I've never checked it before. I have a known good running unit to check....

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Old 05-13-2015, 01:52 PM   #7
greybeard50
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Location: Peru, IN aka "the flats"
Oddometer: 36
XL 350 Wiring

The connector carrying the wires from the alternator can be disconnected from the main harness. There is a factory plug on the alt side of this connector on a Bk/W wire. Simply disconnect the Bk/W plug from the main harness to the ignition coil & points, and reconnect to this pigtail from the alt connector. The entire main harness with all switches, battery, & lights can now be removed. Shazam! A dirt bike!

You now have the simplest path for the electricity to follow. On the down side you also do not have a way to stop the electricity! Install a momentary "ON" button (XR200R 1998 USA SWITCH ASSY.,KILL 35130KT0830) to ground the points & you have done what 99% of XL350 owners did within 6 months of purchase.

Both my XL350's are set this way. I have a parts bike that escaped the stripdown that will, eventually, help restore one to "as purchased" condition.

BTW, my XR200 was sold from the factory with an identical minimalist setup!

greybeard50 screwed with this post 05-13-2015 at 01:57 PM
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Old 05-15-2015, 10:52 PM   #8
XLRacer
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Since I'm just now getting around to tinkering on the racer getting it ready for the next race, I'l answer the question that was asked that I promised to find out.

I tested the stator on my race bike with a one wire setup. Indeed, the black/white wire from the stator to the coil/points does connect to ground when tested in "free space". IE, disconnected from everything else in the circuit.
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Old 05-16-2015, 01:51 PM   #9
greybeard50
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Stator Status

Two of the three separate stators are grounded at the case: the one for ignition (the Bk to Bk/W @ connector) and one for headlight (W to W/Y @ connector).

The third pushes AC energy to the rectifier through the Y & P wires and is referred to as a "floating ground" stator. It's energy becomes full wave Direct Current with a hot and a ground feeding the battery.
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Old 06-03-2015, 09:42 PM   #10
DustyRags
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Just found this thread- I'm chasing a similar ghost. Bike had a bad coil and "possibly a bad stator, but comes with a new one" when I picked it up used. New coil, fuel lines, carb checked (clean), aux tank hooked up, battery charged, kicked and started. Ran a bit, started and stopped it a few times, started running rough, then wouldn't start. Thought I flooded it (too much pressure from the aux tank too high up), so I left it. Came back the next day, and the battery was half-dead. Shouldn't matter, but I figured if I had a bad stator, I might be just running off the battery and once that was dead the bike died.

Charged the battery, kicked it over, caught, roared, rumbled, died. Kicked it again, caught, rumbled, stuttered, died, wouldn't start again.

Stator has proper resistance as per the manual, but grounds out- I thought that meant a bad stator, but looks like I was wrong.

Not meaning to derail the thread here, but I'll be following along and doing similar things. This place is great for that sort of info!

In the meantime, I've got the stator unhooked and gonna see if the battery dies again over night. If not, will try to kick it in the morning, maybe.

Next step- run a single wire setup and see if that'll let it start. If yes, time to work through the wiring harness. If not... you'll see me here again.
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Old 06-04-2015, 01:02 PM   #11
XLRacer
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Running is independent of the battery. These bikes will run battery or not, so in reality you have two problems. Stator has 3 coils....one for ignition, one for headlight, and one for battery/rectifier. Each is independent, not reliant on the other.

Battery issue is separate from running issue.

Battery draining is most likely cause by a bad rectifier. Check it.

Sounds like your carb is in fact not clean....or you have a vacuum leak, poor compression, mis-adjusted valves or dirty points. If used, best to check the condition of them all. If the bike runs with the choke on, or half on, this is a clear indicator of a dirty carb. Merely looking a carb over will not indicate the condition of the fuel passages inside a carb.
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Old 06-04-2015, 01:46 PM   #12
DustyRags
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Agreed on the battery issue- thanks for the note on the rectifier, I'll test that! I checked the battery today, and it held a charge overnight (stator unplugged) so that's a good sign.

Compression seems solid, and it didn't seem to care much whether choke or not, once it was started. Once it stumbles, mucking with the choke did beans. But it IS having serious spark issues- putting the plug on the head and kicking it over might yield a handful of sparks in quick succession (like it should), but more likely will give one or two or none at all. The electricals are definitely funky, so I *know* there's an issue there. Once I have spark, if it's still not working, I'll move on to air, compression, and fuel

Gonna check the points next, and run a wire straight from stator to ignition to see if that fixes it. If yes- clean all connections. If not... I'm not sure. Probably dive into points.

Busy weekend planned, will check back. Thanks for the help, much appreciated! I'm good with mechanicals, but electrics are new to me.
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Old 06-05-2015, 01:15 PM   #13
DustyRags
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Working from home today, so I took my lunch break to chase some wires.

Battery is holding charge- I suspect I wasn't aggressive enough in scraping the multimeter leads through the old filth on the terminals. Woo.

I'm getting a bright blinky light all the way up to the coil/points/stator Y-plug with the coil unplugged and my test light plugged into that plug. Stator works, points work. Unplugging the stator, I'm getting a solid ground through the stator- that's correct. Unplugging the points, I get a ground when the points are closed, and no ground when they're open- correct.

Still no spark.

That points to a bad coil, but the coil is brand new. Bad ground on the coil? Is there a way to check those short of swapping in a known-good one (those are close to $100 these days, I'd rather not get another new one...)

Thoughts? Thanks!
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Old 06-05-2015, 04:52 PM   #14
pommie john
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I tested mine by simply connecting the coil directly to a 6volt torch battery, the big square ones you get on a domestic flashlight. The negative side of the battery goes to ground ( anywhere will do), and the other side goes to the connector on the coil. Flick the points open and closed with a screwdriver and you should get a spark.
That at least takes the magneto and the wiring out of the equation.
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Old 06-06-2015, 06:58 AM   #15
XLRacer
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Quote:
Originally Posted by DustyRags View Post
Working from home today, so I took my lunch break to chase some wires.

Battery is holding charge- I suspect I wasn't aggressive enough in scraping the multimeter leads through the old filth on the terminals. Woo.

I'm getting a bright blinky light all the way up to the coil/points/stator Y-plug with the coil unplugged and my test light plugged into that plug. Stator works, points work. Unplugging the stator, I'm getting a solid ground through the stator- that's correct. Unplugging the points, I get a ground when the points are closed, and no ground when they're open- correct.

Still no spark.

That points to a bad coil, but the coil is brand new. Bad ground on the coil? Is there a way to check those short of swapping in a known-good one (those are close to $100 these days, I'd rather not get another new one...)

Thoughts? Thanks!
Condensor. Replaced that or is it missing altogether? Plug wire. Did the new coil come with one or did you re-use the old?

[IMG][/IMG]
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