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Author Topic: 1975 cb750 k lighting  (Read 750 times)

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Offline patman

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1975 cb750 k lighting
« on: April 24, 2011, 03:41:31 PM »
my lights get brighter as i accelerate and eventually blow. when i checked the battery voltage it was at 16.7v while running at 3000 rpm. when i bought the bike it had an aftermarket universal regulator/rectifier and it was only zip tied in so it had a lot of play.i thought that might have something to do with it. i sure would appreciate the help thanks
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Offline rklystron

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Re: 1975 cb750 k lighting
« Reply #1 on: April 24, 2011, 07:11:28 PM »
Sounds like voltage regulator. You may want to find an OEM Reg and rectifier. If you are having problems with an aftermarket that you did not install and can not find documentation to help isolate or adjust.
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1970 CB750 K0 (Bought in 73)
1972 XL250 (Bought new in 72)
1973 ST90 (Free)
1975 XL250 (Free)
1975 Rickman CR750
1982 CBX1000 Pro-link
1975 CB750 DRAG BIKE
1977 Custom Built CB750 Sturgis Bike (GL front end).
1977 CB750 F2 (Big Resto)
1977 CB750A (Auction Buy)
1978 CB750 K8 (My San Francisco ride)
1984 VFR750 (Bought New)

Offline Spanner 1

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Re: 1975 cb750 k lighting
« Reply #2 on: April 24, 2011, 07:24:55 PM »
Zip tied reg/rect unit should not matter if it has a separate ground ( Green ) wire.... 'Prolly a unit that's meant for a big 'ol battery which would absorb the voltage , unlike your little 14Ah bike battery....... In My Opinion  :). Some folks use a solid state one from Oregon Cycle ( I think... do a search ) ... Good Luck.
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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 Tree

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Re: 1975 cb750 k lighting
« Reply #3 on: April 24, 2011, 07:26:19 PM »
You might consider a unit from Oregon Motorcycle Parts.  I think they warrant them for life.
  Some electrical troubleshooting tips there as well.

http://www.oregonmotorcycleparts.com/Reg_rec_units.html
« Last Edit: April 24, 2011, 07:33:32 PM by Tree »
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Offline patman

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Re: 1975 cb750 k lighting
« Reply #4 on: April 24, 2011, 08:39:45 PM »
i just finished putting in another reg/rec i had laying around still doing the same thing.could it possibly be my alternator or field coil ? has any one else ever had thes problems
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Offline Spanner 1

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Re: 1975 cb750 k lighting
« Reply #5 on: April 24, 2011, 10:29:50 PM »
Bad main ground or battery connections, bad battery.......?
Could not be feild/stator as they can only produce what battery dictates, i.e. battery is not telling the regulator to stop charging when safe voltage ( about 13.5V) is achieved . 'Prolly stuck points in regulator.
« Last Edit: April 24, 2011, 10:34:17 PM by Spanner 1 »
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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....
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