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--- techtalk:ref:elec30 [2020/02/08 06:04]
hippysmack created
+++ techtalk:ref:elec30 [2020/02/09 18:28]
hippysmack [The Doctor71'S 1974 xlh]
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 ====== Ironhead Wiring Mishaps and Meltdowns ======
 \\
+See also illustrated [[techtalk:ref:elec07|1959-1985 Sportster Main Wiring Diagrams (created with reference to the OEM manual)]] in the REF section of the Sportsterpedia. \\
+It's important to have some sort of fail safe mechanism whether a fuse wire, fuse or circuit breaker inline between the battery and the voltage regulator. ((The Doctor71 of the XLFORUM http://xlforum.net/forums/showthread.php?p=5805036#post5805036)) \\
+Else you can unsuspectingly experience a dead short, melted wiring or even watching your bike go up in flames (literally). \\
+It appears that HD's quick fix in 1974 to the meltdown was Service Bulletin #659 adding a fusable wire inline from the battery. \\
+[[techtalk:ih:elec02#fuse_wire|Clich here to see more on the fuse wire]] in the Sportsterpedia. \\
+It's important to have some sort of protection on the main circuit. \\
+If it applies to your ride, you can ward off a potential meltdown in multiple ways. Do whatever works for you:
+  * By following HD Service Bulletin #659.
+  * Installing an extra circuit breaker.
+  * Installing an inline fuse.
+  * Or all of the above.
+====== Broken Horn Bracket ======
+The horn bracket that is mounted along with the key switch between the cylinders has been known to cause meltdowns. \\
+The fact of the bracket breaking (due to being loose, vibration, age etc,) isn't the problem (electrically speaking). \\
+The key switch terminals are bare ended (no insulation). \\
+Should the horn bracket break, the horn will (most likely) swing down & rest on the back of the ignition switch for awhile, shorting the terminals. \\
+The subsequent dead short heats up the wires, melting them and triggers the carnage shown below. \\
+At this point, the motor is dead, no lights, no nothing. You're stranded on the side of the road, wondering just what happened. \\
+===== The Doctor71's 1974 xlh =====
+This happened to my 74 XLH and all initially started by a broken horn bracket: \\
+This particular bike did not come with a fuse wire installed from the factory. So the main circuit was unprotected. \\
+See the 'before' pic of the horn / switch brackets below (taken ≈ 8 months prior to my catastrophic event). \\
+The ends of the ignition switch wires were heat-shrink'd immediately after this pic was taken. \\
+**Note the exposed screws on the back of the ignition switch**. \\
+Next, the meltdown occurs. I phone my son to bring tools, wire, etc etc. I re-wire enough of the bike, while on the side of the road, to get me home. \\
+For the fix, I added a reinforcement to the horn bracket & TIG welded it up, replaced all those wires, & added my own fuse wire. \\
+Before pic. Note the relative pristine condition of the horn mounting bracket, p/n 69129-72. ((photo by The Doctor71 of the XLFORUM http://xlforum.net/forums/showthread.php?p=5805036#post5805036)) \\
+{{:techtalk:ref:elec:74_xlh_wiring_meltdown_1_by_the_doctor71.jpg?direct&300|}} \\
+After pics. Back in the garage, with pics of the horn mounting bracket, et al, after removal. ((photo by The Doctor71 of the XLFORUM http://xlforum.net/forums/showthread.php?p=5805036#post5805036)) \\
+{{:techtalk:ref:elec:74_xlh_wiring_meltdown_2_by_the_doctor71.jpg?direct&230|}} {{:techtalk:ref:elec:74_xlh_wiring_meltdown_3_by_the_doctor71.jpg?direct&230|}} {{:techtalk:ref:elec:74_xlh_wiring_meltdown_4_by_the_doctor71.jpg?direct&230|}}
+First pic below is the RED wire from the solenoid to voltage regulator, note the insulation (on what was the RED wire) has evaporated. \\
+On a '74 XLH, this wire is the main feed that runs from the solenoid to the Delco voltage regulator. \\
+I fully expected this wire to be burnt thru. It wasn't. Another RED wire burnt thru first, otherwise I'm certain it would have burnt thru. \\
+The outer black sheath is mostly in tact. \\
+The second pic shows the wire with the outer sheath removed. Insulation jacket was totally smoked, end to end. \\
+{{:techtalk:ref:elec:74_xlh_wiring_meltdown_5_by_the_doctor71.jpg?direct&230|}}  {{:techtalk:ref:elec:74_xlh_wiring_meltdown_10_by_the_doctor71.jpg?direct&300|}} \\
+Below is what was left of the RED ignition switch wire (about 12 inches was damaged and/or evaporated), which runs from the voltage regulator to ignition switch. \\
+The WHITE wire (feeds the accessory & ignition circuit breakers) and the GREEN wire (feeds lighting circuit breaker) were intact. \\
+(although still damaged due to heat on RED wire) \\
+The outer black sheath housing the RED, WHITE & GREEN wires is mostly in tact except for the damaged 12 inches at the end. \\
+(which had been discarded by the time I took this pic) \\
+Note the RED wire has all the insulation evaporated / melted off in the second pic below. The heat-shrink I installed 8 months earlier is more or less intact.
+{{:techtalk:ref:elec:74_xlh_wiring_meltdown_6_by_the_doctor71.jpg?direct&230|}}
+{{:techtalk:ref:elec:74_xlh_wiring_meltdown_8_by_the_doctor71.jpg?direct&230|}} {{:techtalk:ref:elec:74_xlh_wiring_meltdown_9_by_the_doctor71.jpg?direct&230|}} \\
+Here is the black sheath that houses the RED, WHITE, & GREEN wires running along the backbone of the frame. \\
+The wires inside are "crispy & damaged to various degrees" but not burnt thru in this area. \\
+{{:techtalk:ref:elec:74_xlh_wiring_meltdown_7_by_the_doctor71.jpg?direct&300|}} \\
+===== Hopper's 1977 XLCH =====
+Or: Most carb problems are electrical. ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021)) \\
+Hopper had been fine tuning the Keihin carburetor to get a nice reliable idle without carb farts, stalling, or unwanted high-idling. \\
+Riding around the back roads in the sugar cane fields near home. Coldest morning of the year (50 degrees F , perfect for breaking in a new engine). \\
+I lean out the idle mixture screw so it is idling beautiful, but then it gets a misfire in the midrange. \\
+I head for home. The misfire starts happening at full throttle too. Maybe some of that carb cleaner I sprayed in the idle mix screw hole has dissolved an O-ring? \\
+Or is sitting in a gob in the float bowl and acting like water in the fuel - I have had that happen before. \\
+So I pull into my buddy`s driveway - the aircraft engineer and BMW restorer - to see if maybe he has a 0.80mm drill I can open my intermediate jet up just a tad with. \\
+I let the bike sit there and idle for a good minute or more. Beautiful. Perfect in fact. \\
+I kill the engine and get off. Ferkin ell, there`s smoke coming off the battery. \\
+I look and see the positive wire from the battery to the regulator is glowing red hot. \\
+Then before my eyes, flames start licking up the battery. \\
+The rubber battery box mount is on fire and the flames are licking at the rubber mount above it. \\
+As I look for the nearest hose, there is a cloud of smoke about 6-foot high and six-foot wide covering the whole bike. I cant even see the seat. \\
+Hose, hose, hose. My buddy is not home. Where is the damn yard faucet? There are hoses lying all over the drive. \\
+I follow one to the end - a sprinkler. The other end - nothing. \\
+Just lying in the garden. He has bore (well) water and the pump switch is inside the (locked) garage. \\
+The cloud of smoke is getting smaller, but I can't blow the flames out, or get a glove in there to beat them out, behind the battery. \\
+The fire is burning quite well in there. \\
+I am getting ready to stand back and watch a bike I have owned for 31 years and just spent six months restoring go up in flames before my eyes. \\
+The English language simply does not have the words to describe that feeling. \\
+I ain`t taking this lying down. Around the side of the house, bucket, bucket, bucket. \\
+My buddies` home brewing kit is there, with 5-gallon plastic buckets for washing bottles in... with water in one of them. \\
+Kersplash, problem solved. Whew, no English words to describe that feeling either. \\
+At first, I am cursing the recently installed Accel regulator, which is too hot to touch. \\
+There were plenty of English words to describe that feeling. Many starting with F and C and of Saxon origin. \\
+Then I am checking out the fried wiring to the ignition switch and see the horn bracket has broken from vibration. \\
+(the one between the two cylinders, right above the ignition switch) \\
+The highly conductive metal horn bracket has lobbed straight onto those bare screw connections on the back of the ignition switch. \\
+(right on , of course, the main power wire from the battery). More words of Saxon origin. \\
+Lucky my BM riding buddy was not home to see all this. And he lives uphill from my place, so I roll the bike home and into the shed. \\
+Had time before work to strip off the seat and ignition switch and remove the battery. \\
+Fried wires up through the main loom from the battery area to the ignition switch. \\
+Looks like I can splice in new wires without replacing the whole loom. Bummer, original unmolested factory loom - well, was. \\
+And as usual, the circuit breakers did not break. Or were breaking temporarily and resetting straight away - causing that misfire, I would bet money. \\
+I will be wiring an inline fuse into that main battery wire. \\
+Oh well, just another day with the Ironhead. Gotta go and buy some heat shrink tubing. \\
+The bracket is rubber mounted. \\
+The part that broke was the top part that bolts to the big heavy bridge bolted between the two heads, and the rubber bobbin attaches to it. \\
+So the actual horn and small bracket are isolated from the vibes. \\
+It broke right where the thin (.080" or so) bracket stuck out past the heavy (3/8") bridge. \\
+The bracket is sort of roughly chromed so it looks like there was some hydrogen embrittlement from the chroming. \\
+That combined with HD vibration. Poor design that lets the bracket flex in use and the repeated heat cycles of the between the cylinder location. \\
+The break is crystalized and you can see it was broke 3/4 of the way through for a long time before. \\
+A TIG weld repair with gussets should work to stop future flexing, and a properly insulated ignition switch set up will stop it from happening again. \\
+See that broken horn bracket right where my finger is pointing in the pic below. \\
+And the bare terminals right below it. And the shiny copper wire direct from the battery, that used to have red insulation on it. \\
+Well toasted. Nothing to insulate those terminals if something goes wrong. \\
+In the third pic below is what fractured and fell down on top of those bare hot terminals. \\
+{{:techtalk:ref:elec:74_xlh_wiring_meltdown_1_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_2_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_3_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) \\
+This is all that was left of the main power wire from the battery to the ignition switch. \\
+A good foot of copper simply vaporized and disappeared. \\
+{{:techtalk:ref:elec:74_xlh_wiring_meltdown_4_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) \\
+Nearby wires were well fried too, the ones going to the breakers after they leave the switch in the first pic below. \\
+The others are the other end of the main loom going under the seat post area. \\
+{{:techtalk:ref:elec:74_xlh_wiring_meltdown_5_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_6_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_7_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) \\
+Took some fixing. \\
+I opened the melted outer cover, replaced the fully toasted wires, patched some singed ones with fusion tape and Nitto tape, heat shrink and whatever it took. \\
+Had to solder some new sections in some. \\
+{{:techtalk:ref:elec:74_xlh_wiring_meltdown_8_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_9_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) \\
+The rat's nest under the seat survived unscathed except the wires to the ignition breaker and lights breaker. \\
+I added another fourth breaker, a 30amp job, right next to the battery so this cant happen again. \\
+The closeness of wires and terminals and steel frame and fender parts is absolutely terrifying. \\
+But I figure the master breaker right at the battery will prevent any meltdown if a bottle cap or something should blow in there off the road and arc those terminals. \\
+{{:techtalk:ref:elec:74_xlh_wiring_meltdown_10_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_11_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) \\
+And the ignition switch now has a cocoon of fusion tape and Nitto tape to insulate those terminals plus some super heavy duty heat shrink to go over top off all that. \\
+Also the patched and spliced main loom with a couple of layers of Nitto tape wound around it in opposite directions. \\
+And the TIG welded horn bracket with a strengthened patch so hopefully it won`t break again. \\
+{{:techtalk:ref:elec:74_xlh_wiring_meltdown_12_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) {{:techtalk:ref:elec:74_xlh_wiring_meltdown_13_by_hopper.jpg?direct&300|}} ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=277021&page=4)) \\
 \\

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