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Author Topic: very very crappy day  (Read 1466 times)

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Offline KRONUS0100

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very very crappy day
« on: May 28, 2011, 12:40:48 PM »
1976 CB750F
new built by me wire harness
Hondaman fusebox and resistor pak
regulator and rectifier from Oregon Motorcycle Parts
relays added for ignition coils, horn, hi beams, and low beams
wiring is not done because the horns, turn signals, and headlight are not on the bike at moment
decided today was day ( after 4 months working on harness to make sure it was right) to put battery in an test for power
i double checked all wiring and connections prior to putting in battery
cooked ground wire on connection of battery negative
was on other side of bike so i did not immediately notice the smoke
have looked at wire diagrams and it occurs to me...why does rectifier always have 12 volts?( It attaches to positive battery cable at the starter relay post.) that would explain the minimal sparking upon connection of negative cable.
but why did that cook the ground wire that connects the alternator, the regulator, and the rectifier to the frame?
do I have a bad new rectifier from Oregon Parts, or do I have a bad alternator?  bike was charging fine before this project.
I am pissed an upset, studying wiring diagrams an my notes and wishing for lots of beer.
Incedentaly, nothing else was hurt, just that ground wire.
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MATT
current bikes:  1976 CB750F, 1981 GS1100E
bikes owned:1981 GL1100I, 1990 GS500E, 1981 GS850, 1977 and 1979 GS750, 1974 CB750, 1975 CB750, and a 1982 GS750E

Offline CBGhia

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Re: very very crappy day
« Reply #1 on: May 28, 2011, 01:09:19 PM »
Something positive is shorting to the frame.
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Quote from: dave500 on February 14, 2014, 03:53:33 AM
if you dont trial spin the camshaft in the head and cover you are a novice,with no natural mechanical appitude,destined for destruction.
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Offline Hush

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Re: very very crappy day
« Reply #2 on: May 28, 2011, 02:26:33 PM »
Same thing happened on my partner's bike, major cook-up and I had to rewire half the loom, never found a problem and rewired it exactly the same.  I can only asume that there was a bad connection or crud under an earth wire and when I rebuilt it I made a decent job of cleaning everything.
Sometimes there is no explanation for "#$%* happening"! ;D
Sorry your work got toasted but sounds like you saved most of it, onward and upward Kronus. :)
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline dave500

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Re: very very crappy day
« Reply #3 on: May 28, 2011, 02:33:51 PM »
the output of the rectifier goes to the battery positive or the battery side of the starter relay,the diodes within the rectifier should be stopping any reverse flow at the rectifier,you do have the battery the correct way around i guess.
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Offline Spanner 1

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Re: very very crappy day
« Reply #4 on: May 28, 2011, 02:44:13 PM »
Yep, on all our bikes with the battery installed there are 2 things which are 'hot' all the time. The red/yellow wire to the rectifier (+) and the red wire thru' the 15A main fuse all the way up to the ignition switch, battery in = power to those two places..... soooo, if the ground wire melted either the red wire is nicked/bare and shorted to frame before the fuse block ( not likely ) or the rectifier is shorted-out ( likely ). Usual cause is charger put on the bike battery with + and- reversed or car type charger with say 10A output connected to battery ( battery in bike ). The little bike battery does not present enough load on the car battery charger and the voltage will be too high and blow the rectifier  :(
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If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Offline KRONUS0100

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Re: very very crappy day
« Reply #5 on: May 28, 2011, 03:12:12 PM »
went out an had a look few minutes ago.  the fuses are all good.  did quick ohm test on alt yellow wires and green an white wires of alt an regulator.  havent tested rectifier yet, but its new.  did pull final drive cover an really dont like the condition of those connectors, so they will get replaced i reckon.  i have the battery on charge now so i can test it tommorrow, will try again then.  still no sign of a short in any of the wires, cept mebbe those old brittle connectors under the cover.
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MATT
current bikes:  1976 CB750F, 1981 GS1100E
bikes owned:1981 GL1100I, 1990 GS500E, 1981 GS850, 1977 and 1979 GS750, 1974 CB750, 1975 CB750, and a 1982 GS750E

Offline Spanner 1

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Re: very very crappy day
« Reply #6 on: May 28, 2011, 09:32:45 PM »
I should have said red/white wire feeds +battery voltage to the rectifier (not red/yellow ). Again, the battery connects directly to the rectifier, no fuses involved. Need to unplug the rect. plug ( has 3 yellow/ green/ red-w ) and test the rectifier.... or fuss with stuff that's not relevant ( sorry  :D ).
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If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Offline KRONUS0100

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Re: very very crappy day
« Reply #7 on: May 29, 2011, 08:57:43 AM »
turns out its continuity between power an ground on the rectifier.  allready talked with Tony at Oregon Motorcycle Parts.  It will be on its way to him Tuesday for repair or replacement.
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MATT
current bikes:  1976 CB750F, 1981 GS1100E
bikes owned:1981 GL1100I, 1990 GS500E, 1981 GS850, 1977 and 1979 GS750, 1974 CB750, 1975 CB750, and a 1982 GS750E

Offline dave500

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Re: very very crappy day
« Reply #8 on: May 30, 2011, 12:38:12 AM »
yeah stuff new can be bad oddly,,i had a leese neville alternator repaired on an old mack,when i reconnected the battery there was quite a spark,nothing was turned on,,it was one diode in the rectifier on the alternator,disconnecting it proved it.
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Offline motocyconomad

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Re: very very crappy day
« Reply #9 on: June 27, 2011, 11:41:51 AM »
Quote from: Spanner 1 on May 28, 2011, 02:44:13 PM
Yep, on all our bikes with the battery installed there are 2 things which are 'hot' all the time. The red/yellow wire to the rectifier (+) and the red wire thru' the 15A main fuse all the way up to the ignition switch, battery in = power to those two places..... soooo, if the ground wire melted either the red wire is nicked/bare and shorted to frame before the fuse block ( not likely ) or the rectifier is shorted-out ( likely ). Usual cause is charger put on the bike battery with + and- reversed or car type charger with say 10A output connected to battery ( battery in bike ). The little bike battery does not present enough load on the car battery charger and the voltage will be too high and blow the rectifier  :(
oh this sounds like the #$%* I'm in now
I let my "buddy" who knows better, hook up the little bit of wiring left after I swaped out motors so I could go over the harness I've made with him and be sure nothing is wrong with it electric wise. I leave for a minute to come back and see the dip#$%* hooked up pumping 30A to get the bike to fire. Pretty sure they burn my reg/rec I'll be going through the rest of it to see what else got #$%*ed up.
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