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Author Topic: 74 cb750, no spark, updated:FIXED: NOW IT RUNS!  (Read 7218 times)

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Offline 13ill

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74 cb750, no spark, updated:FIXED: NOW IT RUNS!
« on: January 17, 2010, 04:37:08 PM »
trying to fire the old girl up, no spark. noticed the red and green leads pictured here unplugged? anyone know where they go if anywhere? i cannot find anything they should be connected too.
« Last Edit: January 18, 2010, 08:27:36 AM by 13ill »
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Offline Toxic

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Re: 74 cb750, no spark, are these two leads important? (pic)
« Reply #1 on: January 17, 2010, 05:41:26 PM »
Check your wiring diagram, I believe it shows a red wire coming off of the starter selenoid that is not connected.
The green would be a spare ground.

Anyway here is a free bump to the top as I am sure one of the many electrical gurus can give you a definet answer.
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Offline Hush

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Re: 74 cb750, no spark, are these two leads important? (pic)
« Reply #2 on: January 17, 2010, 05:45:28 PM »
Check fuses, battery charge, kill switch position.............you'd be suprised how many forget. ;D
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Offline paulages

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Re: 74 cb750, no spark, are these two leads important? (pic)
« Reply #3 on: January 17, 2010, 05:54:51 PM »
not important.
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paul
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1974 CB550 (735cc)
1976 CB550 (590cc) road racer
1973 CB750K3
1972 NORTON Commando Combat
1996 KLX650 R

Offline 13ill

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Re: 74 cb750, no spark, are these two leads important? (pic)
« Reply #4 on: January 18, 2010, 04:30:07 AM »
Quote from: paulages on January 17, 2010, 05:54:51 PM
not important.

thanks, kind of figured that. maybe used on euro spec bikes or another model that shares the harness?

charge good, fuses good, kill switch in correct position.
« Last Edit: January 18, 2010, 04:35:14 AM by 13ill »
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Offline Johnie

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Re: 74 cb750, no spark, are these two leads important? (pic)
« Reply #5 on: January 18, 2010, 04:45:46 AM »
Yah, that green is an extra ground. I think I saw a post here that the extra red is for a 3 prong flasher unit. Most of us has a 2 prong flasher.
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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 13ill

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Re: 74 cb750, no spark, are these two leads important? (pic)
« Reply #6 on: January 18, 2010, 08:26:16 AM »
well, it runs. took the points cover off, weak spark out off one set of points, none out of the other. dressed 'em both with a bit 'o sandpaper followed by a dollar bill. voila, now i have spark up to the plugs.
made a test tank out of an old ketchup bottle (don't try this at home kids), filled the carbs and after a bit of coaxing the old girl fired up.
okay, now to the next step......
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Offline mystic_1

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Re: 74 cb750, no spark, updated:FIXED: NOW IT RUNS!
« Reply #7 on: January 18, 2010, 09:05:23 AM »
Glad you got it sorted!  By the by, sandpaper isn't the best thing to use on points for a variety of reasons.  It'll work, sure, but a real points file is better.  Try to keep the point contact surfaces flat and parallel!

mystic_1
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