Prince George Vintage Motorcycle Club
Technical Section => Electrical => Topic started by: Dennis on May 15, 2020, 12:38:35 PM
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My Smithers XS650 Bobber failed last Sunday ? abruptly there was no power to anything.
Got the bike home and determined I had a catastrophic battery fail. The computer controlled battery charger flashed defective, and charging overnight with an old school 2 amp charger did not charge it up. In fact when tested it showed various voltage readings, none above 9 volts.
I replaced the battery. Fortunately the one I bought for the XS1100 trike is the same, so I installed it and everything worked accept spark. No spark whatsoever.
I run a Pamco Pete (now called XSCharge) electronic ignition. Its a magnetic pick up that uses the mechanical advance. The literature warns that disconnecting the battery when the engine runs may damage it. I have read similar things on the WWW about destroying electronic ignition by disconnecting the battery while the engine is running, or even having one of the spark plugs out but ungrounded.
I've ordered a replacement.
Query: Anyone know why and an electronic ignition would fail because a sudden power loss? It appears from the WWW that is occurs in automobiles as well, but I couldn't find why. It is counter-intuitive to me. I could understand a surge burning out the little components, but no power?
Peace & dielectric Grease, Dennis
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Disclaimer: My electrical/electronic knowledge is getting dated, but here?s what I know/believe.
You?re right; these issues exist in automobiles as well as motorcycles. That?s because they all use similar systems and components ? electricity behaves the same regardless of where it?s in use. Forty years ago, when computers came into common use in autos, one of the things we were warned about was to make sure the ignition key was turned off when disconnecting the battery. It?s also not a good idea to do any welding on a vehicle with the computer connected to the car?s system as transient induced voltages from the welding current can damage the computer internal circuitry ? sometimes in a subtle way that won?t be noticed immediately.
Maybe the best example I can think of is what goes on inside a simple electromagnetic relay. When the relay is activated, it uses a magnetic field in its core to generate the force needed to hold its contacts closed. When the relay is deactivated (i.e. the switch which had it engaged is opened), the magnetic field in the relay core collapses and, in doing so, induces a voltage in itself which can reach levels (depending on the relay) exceeding 70 volts. This is more than most FET-type transistors can withstand ? generally, anything over 18 volts could be dangerous. Your experience of sudden battery failure may be similar to turning off any relay on your bike and, since it happened with the ignition switch on, it was able to send a voltage spike into the system which affected a sensitive component of your ignition module.
That?s only one possible cause. I won?t attempt to diagnose your individual case.
Hope this helps.
Theo
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Thanks Theo.
I have a replacement coming. $99 Cdn. I have a stash of old XS650 parts including two sets of points. I contemplated Jerry rigging them, but decided $99 plus waiting a few more days is worth it.
As Paul says, "always have a back up bike." I'll be riding the Yamaha XT350 at least until my parts arrive. If it turns out my ignition is not the problem and it will take more head scratching to figure out, I'll insure my BMW R65L. Its on a Collector Plate so the insurance is actually pretty cheap.
Peace & dielectric Grease, Dennis
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I have not tested the new electronic ignition yet but ? Rusty Bucket suggested I really should try my coil first. I've never had a coil fail in 39 years of riding.
I took out my coil and got proper (4.5 ohms) primary, and complete dead nothing (reads "OL" on Fluke 115) on the secondary. I checked my ohm meter with other coils in my shop including my brand new known to be good Dyna coils from my Trike. All read a few ohms on primary and lots of kiloohms on secondary which is expected. It follows that my Fluke 115 ohmmeter works, and my coil is fugged.
"Replace with known good parts" is an expensive way of diagnosing a problem, but since I had a dual output coil compatible with my ignition system why not wire it in and try? I did. No spark.
I will wire in the new electronic ignition module I have with the new Dyna coil and see if that works.
Yes, I've checked the fuses. I have 12 plus volts going to the coils and ignition.
It strikes me as odd, that both my coil and ignition would catastrophically fail at the exact same time that the battery catastrophically failed.
Peace & dielectric grease, Dennis
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New electronic ignition + new Dyna coil = spark.
However. Since concluding that my old coil was fugged merely because of the resistance test, I decided to try it back on the bike with the new electronic ignition. IT WORKS.
My first diagnosis was correct; the sudden failure of the battery took out the electronic ignition.
I am curious about my coil testing skills or tools. If the old coil is creating spark why did it fail the bench test?
Funny sideline: last week I ordered a replacement coil from the same vendor; XS650Direct. I was concerned because the 4.5 ohm rating of the old coil is not recommended for the electronic ignition (Pamco prior and now called XSCharge) despite XS650Direct selling a kit which includes the 4.5 ohm rated coil and the electronic ignition. I went to send them an email to ask, and in going through my old emails found I had asked them the same question back in 2014 when I purchased the Pamco ignition first, and later a replacement coil (I originally wired the bike with the 30 year old coil). In looking through my emails and order confirmations, I saw that I bought two new coils at the same time; the 4.5 ohm discussed above, and a "hi-performance ignition coil." Totally forgot. At the bottom of my stack of bins I have one marked "XS650 new and unused." I dug in, found the brand new unused hi-performance coil, wires and caps. Checked: 2.5 ohm which is in range for my electronic ignition. I might as well use it so I installed it.
I'll put the new replacement coil I just ordered in the "new and unused" bin and probably forget about it also.
Peace & Grease, Dennis
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With the new electronic ignition and hi-performance coil installed, I had to squeeze all of this back under the gas tank. Despite my preferred technique of soldering and shrink wrapping all my connections, this bike was wired with crimp connectors so I stayed with the program.
(https://i.imgur.com/KLPdTbt.jpg)
Might as well fix other things while the bike is on the rack. My taillight lens was cracked, so it got some reinforcement.
(https://i.imgur.com/Kzh3cIJ.jpg)
Both headlight and tail light had burnt out filaments so the bulbs were replaced. Rear brake switch connector spring was broke so I fixed it. Lubed up the clutch cable. Routine stuff.
(https://i.imgur.com/Wmsqf7A.jpg)
Lowered the bike and gave the kick starter a nudge. I popped instantly to life. The hi-performance coil really makes a difference on starting.
Instantly I had gasoline pouring out of one carb.
(https://i.imgur.com/XqmLpLF.jpg)
This is such a common old motorcycle occurrence that I didn't bat an eye. Within 20 minutes the carb was pulled, float bowl removed, air compressor set up and blew a few seconds of air through the fuel inlet, re-assembled and put back on the bike. Complete success.
Peace and Grease, Dennis
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With the new electronic ignition and new hi-performance coil, I was able to do a Tuesday ride (June 9th), and a trip to Vanderhoof and back problem free. Then on last night's Bike Night (June 16th), my bike broke down. Suddenly the engine died without a sputter, and I knew right away it was a spark issue.
Neil gave me a pillion ride to get my truck and helped me load it.
Later, back at the garage, and with much further help from Neil, we diagnosed the problem by testing volts, continuity and ohms. We also used a few sacrificial fuses. The new Hi-performance coil was shorting through the primary circuit, taking out the fuse in the process. Funny, because earlier in this thread I said I doubted my coil failed in the first breakdown because I've never had one fail in 39 years of motorcycles. I have now.
Installed the old coil, tested and we got spark.
After the Members left, I put everything back together and it started on the first kick.
(https://i.imgur.com/cbd2oOJ.jpg)
(https://i.imgur.com/uwY6L41.jpg)
Peace & Grease, Dennis.