Author Topic: Where to start....  (Read 2255 times)

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Offline Sdsbassist

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  • Gus, Austin, MN.
Where to start....
« on: March 11, 2012, 03:22:37 PM »
So close to the first test ride...carbs fixed up, gas in tank. Ive run it before in the garage with zero issues.

So I take it out of the garage and put it gear, start down the driveway and end the end of the drivrway and then total shutdown. No power, no electrical, zero.

Ichecked the first three fuses under the cover and they all look good.

What should I check next?
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline ekpent

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Re: Where to start....
« Reply #1 on: March 11, 2012, 03:28:54 PM »
My bike,750, let me down once when the ignition wires came apart at the push in conection to the main harness which will be under the gas tank. No power-no nothing.Easy fix luckily. Also check your battery connections,make sure the main fuse really is good and also you did not accidently hit the kill button.
« Last Edit: March 11, 2012, 03:32:10 PM by ekpent »

Offline Sdsbassist

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Re: Where to start....
« Reply #2 on: March 11, 2012, 03:33:06 PM »
I dod have my tank off. I will check there. Is there a main fuse somewhere?
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline Johnie

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Re: Where to start....
« Reply #3 on: March 11, 2012, 03:43:49 PM »
Main fuse holder is under the left side cover. It is a small black plastic box thing.
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Where to start....
« Reply #4 on: March 11, 2012, 04:40:55 PM »
Ok.,i will peek for that too.
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline BeSeeingYou

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Re: Where to start....
« Reply #5 on: March 11, 2012, 05:13:34 PM »
Check the simple things first.  The battery connection.  Had the negative come loose and lost the nut on a ride.  Used a stick to wedge the connection onto the battery post to get me home.  Had a thread about it some time ago. ;D

http://forums.sohc4.net/index.php?topic=50781.msg538796#msg538796
« Last Edit: March 11, 2012, 05:22:00 PM by srust58 »

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Where to start....
« Reply #6 on: March 11, 2012, 05:17:08 PM »
Near where the pos cable connects to the sol, the0e is a solid red wire that is connected to nothing. Related?

Can I get a pic of where to find the main fuse?

74 cb759
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Where to start....
« Reply #7 on: March 11, 2012, 05:17:47 PM »
Near where the pos cable connects to the sol, there is a solid red wire that is connected to nothing. Related?

Can I get a pic of where to find the main fuse?

74 cb750
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Where to start....
« Reply #8 on: March 11, 2012, 05:25:38 PM »
BTW chexked ignition and ground, both good
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline BeSeeingYou

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Re: Where to start....
« Reply #9 on: March 11, 2012, 05:37:58 PM »
There is a solid red wire that should run from the main fuse to the solenoid.  Red/white to the rectifier and yellow/red to the starter button.  And of course the main red from the battery.  this is from my 76 750F wire diagram.  Don't know if yours would be different.

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Where to start....
« Reply #10 on: March 11, 2012, 05:56:14 PM »
this is a little solid red that comes off the main red positive cable.
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline LesterPiglet

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Re: Where to start....
« Reply #11 on: March 11, 2012, 06:03:16 PM »
As far as I can see there are only two reds. A thick one to the solenoid and a thin one to a connector and then on to the fusebox.
'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


Les Ross.            Certified by a Professional

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Where to start....
« Reply #12 on: March 11, 2012, 06:20:36 PM »
heres what I have got:



I did just try and jump the sol and the starter fired off nicely.
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Where to start....
« Reply #13 on: March 11, 2012, 06:24:21 PM »
I think I only have three fuses, and they all seem to be functioning fine.
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Where to start....
« Reply #14 on: March 11, 2012, 07:32:17 PM »
Ok. So I think I got it. For some reason wasnt getting power from bat to switch somewhere between the connector from the fuse to the main harness. Instead of tearing into the harness, I just ran a new wire from the connector to the connextor for the switch. Works great now. Sounds like a decent fix?
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

DH

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Re: Where to start....
« Reply #15 on: March 11, 2012, 08:10:06 PM »
check the harness connector between fuse box and main harness for corroded terminals inside the plug. Make sertain current is passing THRU the main fuse before calling it good.

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Where to start....
« Reply #16 on: March 11, 2012, 08:13:14 PM »
I hooked it up from the connector coming from the fuse box, not into.
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline Artf0rm

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Re: Where to start....
« Reply #17 on: March 11, 2012, 08:22:00 PM »
I had a full shut down once.  It was my first night ride after I thought I had all the gremlins worked out.  All my lights went out and the bike lost power instantly.  Turned out to be a bad ground contact.   Make sure your grounds are making good contact.

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Where to start....
« Reply #18 on: March 11, 2012, 08:25:01 PM »
Used a volt meter to check connecters and used frame and batery ground.
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

DH

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Re: Where to start....
« Reply #19 on: March 11, 2012, 08:31:00 PM »
I hooked it up from the connector coming from the fuse box, not into.



Gotcha.....possible the keyswitch is intermittantly flaking out?
Just a thought...might be wiring..
« Last Edit: March 11, 2012, 08:33:52 PM by DH »

Offline Sdsbassist

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  • Gus, Austin, MN.
Re: Where to start....
« Reply #20 on: March 11, 2012, 08:33:13 PM »
Took it apart and cleaned it all. Pretty sure it wasnt that. Cant wait to ride tomorrow
Gus, Austin, MN.
Current Bike:  75 750F

Past bikes: 76 750K - "Iowa Blue",78 750K Craigslist find - "Black Beth;" 77 CB750K Basketcase, with a 75K engine; 1970 Cb750 K1, "Rosa Luxembourg"
74 cb750, 75 cb550, 77 kawa 650, 81 virago 750, 83 virago 920, 80 Honda Twinstar 200, 71 Honda CT70, 1971 Honda CB750 Rat Project "Black Dahlia Bitsa"

Offline MasterChief750

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Re: Where to start....
« Reply #21 on: March 11, 2012, 08:36:19 PM »
i had exactly the same thing and the contacts in the keyswitch were shot. replaced the contacts and all is well. i would try looking there.
1978 CB750 K - Project Red Headed Step Child
1976 CB750 K - Drag Bike
Some things i know, others i dont.
I AM THE STIG
Sam is THE STIG
he said i can be STIG3 tho