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  1. #1
    CB750 Addict Dave's Avatar
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    Lightbulb LED Lighting conversion

    I'm planning to convert my lighting over to LED. All 4 turn signals and tail lamp. 1974 CB750k

    My main reason for doing this is that the filaments break from vibration within days of replacing the bulbs in my front blinkers. Also, the LED's are brighter and the bulb I'm getting for the tail is even brighter and flashes 3 times before going steady when you hit the brakes.

    The old flasher won't work with LED bulbs so you need to replace it with an LED flasher.

    1157 LED Bulb X4
    FL2-RED LED Bulb Electronic Flasher X1
    1157 LED Bulb w/ Brake Flasher X1 <-- This is an awesome safety enhancement, get it

    PS I already run a Cibie Headlamp, possibly not legal in the US but who cares, so I'm not converting the headlamp. The shape of the beam provides higher visibility for me, and less glare to oncoming drivers. If you get one, they come in left or right, make sure to get the correct one for your area.

    I forgot about this when I orginally posted. You have to do some modifications to the blinker indicator lamp wiring for this all to work or, just remove the lamp. I'm no artist but here's a drawing showing before and after I've added 2 diodes. I tore apart an old 12v adapter that plugged into the wall to get the diodes out.

    Click image for larger version. 

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    Update, superbright LEDs now sells a kit for this single indicator lamp conversion.
    https://www.superbrightleds.com/cat/...e_Kit,60,6206:
    Last edited by Dave; 06-29-2016 at 09:17 PM. Reason: Corrected diode direction in wiring diagram

  2. #2
    CB750 New Member FrostDesigns's Avatar
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    Hey Dave, thanks for the write up, i just installed some pretty basic bullet style LED turn signals on my 750k8. Im having what seem to be the same problems you had until you figured out altering the wires. I'm assuming since i get power off of both left or both right wires that i need to just run them both into the power side of the LED signal wire and run my own ground off of the LED light? or is my power issue in the flasher relay? i figured i would need a different one. I already have the rear lights wired up and they light up but don't flash. Thanks for any help!!

  3. #3
    CB750 Guru amc49's Avatar
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    Your mod drawing incorrect, you have the diodes blocking any power getting into the bulb, there would be no light there. Turn your diode triangles around 180.

    The flasher is the issue, LEDs do not flow as much power as incandescents and the flasher then does not get enough power to load it enough to flash. Use an electronic flasher made specifically for LEDs.

  4. #4
    CB750 New Member FrostDesigns's Avatar
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    So I shouldn't run the 2 power wires coming off of the bike into the power side of the light and make my own ground to the frame??

  5. #5
    CB750 Addict Dave's Avatar
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    Quote Originally Posted by amc49 View Post
    Your mod drawing incorrect, you have the diodes blocking any power getting into the bulb, there would be no light there. Turn your diode triangles around 180.

    The flasher is the issue, LEDs do not flow as much power as incandescents and the flasher then does not get enough power to load it enough to flash. Use an electronic flasher made specifically for LEDs.
    Opps, I corrected the diode direction, made the sentence about the flasher clearer, and added a picture of a diode for those not familiar with electronics icons.

    The problem is not the flasher. The problem is the way the indicator lamp works. On bikes with a single turn signal indicator lamp the two original wires going to it are both positive. One from the left blinker lamp circuit and one from the right blinker lamp circuit. This works fine with the old flasher but not the new LED flashers, hence the modification required.
    Last edited by Dave; 05-07-2016 at 09:36 AM.

  6. #6
    CB750 Addict Dave's Avatar
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    Quote Originally Posted by FrostDesigns View Post
    So I shouldn't run the 2 power wires coming off of the bike into the power side of the light and make my own ground to the frame??
    If you mean the two wires that originally go to the indicator lamp then yes but, you must add the 2 diodes inline or all 4 blinkers will flash at once.

    You must replace the old flasher with an LED flasher too. Make sure you hook up the flasher correctly the 1st time. It will burn out instantly if you get the wires backwards.
    Last edited by Dave; 05-07-2016 at 09:52 AM.

  7. #7
    CB750 New Member ALPHASMURF's Avatar
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    I have a all in one tail light and turn signal and there are only 2 wires for the blinker setup. do i need a 2 diodes per line then?

  8. #8
    CB750 Addict Dave's Avatar
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    Quote Originally Posted by ALPHASMURF View Post
    I have a all in one tail light and turn signal and there are only 2 wires for the blinker setup. do i need a 2 diodes per line then?
    The diodes are for the turn signal "indicator" lamp up near the gauges.

    Your all-in-one tail lamp will wire up just like the original parts. If it has LED lamps in it, you will need the LED flasher and indicator lamp wiring mod.

    (Assuming your talking about an early model CB750 with a single indicator lamp)

  9. #9
    CB750 Member Ron1's Avatar
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    Hey guys! Where is the flasher located? Also, what do I do if my bike has two signal indicator bulbs (one right and one left). I have a 1977 CB750K. Thanks!

  10. #10
    CB750 Addict Dave's Avatar
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    Depends on what bike Ron. Separate L/R indicators won't require any mods.
    96% of the time I edit my replies so check back for updates if it isn't at least an hour old

  11. #11
    CB750 Enthusiast mrtelec's Avatar
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    Frostdesigns did you ever get your led's working? I am going through my k8 right now and will be trying to tackle the turn signals next. do you remember what you used and what if any mods you may have done. thank you

  12. #12
    CB750 Addict Wez_'s Avatar
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    Ressurect this thread! This is great information

  13. #13
    CB750 Enthusiast mrtelec's Avatar
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    On my 1978 750k there are individual turn signal lights on the dash so you do not need the diode, just the earlier models with one indicator light in dash. I wound up using led bulbs in the front turn signals/running lights and tail/stop light. then put new leds in the dash and the speedometer and tach. I had to replace the turn signal flasher to an electronic led flasher as the old style flasher sees the lower resistance of the flasher as being a dead bulb and they will just stay on and not flash. The rear turn signals got led light bulbs but I had to use a 20w inline resistor for the flasher to see the load on the circuit. I put the resistors on the rear as they are only used during turning where the fronts are on always so less draw on charging system. The results are amazing. I live in a rural area with no street lights and the dash, speedometer and tach are so easy to see compared to the old dim bulbs day or night. for the headlight I went with a 7" headlight with a h4 halogen bulb that is 20/40 watt. It lights up the road 5 times more than the original sealed beam which is now in a box with the rest of the original parts :-)

  14. #14
    CB750 Addict Wez_'s Avatar
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    Wow guys....!!! Thanka so much. This id's the reason why forums are so great!!

    Anyone else?

    I was also thinking about just adding resistance in series to the sensitive circuits so this is great to hear.

    Im still soaking this in...might need a day or two still...also once i know what part of the circuits to address I'll talk with the electrical engineers at work. Perhaps they'll know another way to address the issue.

    Thanks again mrtelec

  15. #15
    CB750 Addict Wez_'s Avatar
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    Dave....thanks too!

  16. #16
    CB750 Addict Dave's Avatar
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    Wez, superbright also sells load resistors.
    96% of the time I edit my replies so check back for updates if it isn't at least an hour old

  17. #17
    CB750 Enthusiast mrtelec's Avatar
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    I got all my stuff for my 78 750k led turn signals on ebay for about $30, you can find the stuff by searching ebay for these items.

    2 x CARCHET 25W LED Turn Signal Light Load Resistor (get the ones with the bullet connectors on them and they are plug and play)
    Front Signal 1157 19 White LED Light Bulbs (Set of 2, 1 Pair) 2057 1157A 3496 ( front running/turn signal )
    LF1-S-PIN Motor 2 Pin 12V Electronic LED Turn Indicator Flasher Blinker Relay (I changed the connectors on it to male spade connectors to fit the harness)
    10X Pure White BA9S 7 LED Car Wedge Interior Panel Light 12V US T4W 1895 57 233 ( used these for dash and speedometer and tach gauges)
    1157 White LED Bulb replacement 12 Leds 1in diameter 2 function (rear tail light)
    US Ship 2Pcs 9-SMD DC 12V BA15S/1156 G18 White LED Car Bulbs For Parking Light (rear turning signals)

  18. #18
    CB750 Addict Dave's Avatar
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    Load resistors are to make the original flasher work with LED blinker bulbs, you don't need them if you swap to an LED flasher unit. The more expensive LED units even have adjustable blink speed.

    The flasher from Superbright plugs right in but, you can easily plug it in backwards because polarity don't matter on the original ones. If you do it'll pop instantly, so make sure you have the polarity right.
    96% of the time I edit my replies so check back for updates if it isn't at least an hour old

  19. #19
    CB750 Enthusiast mrtelec's Avatar
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    Dave I might have to try the led flasher you suggest, I did a little math when I put this all together and I had 200,000 milliamps on the 1 bulb, 250, 000 milliamps on the other and even less for the bulb in the dash and they failed to trip the flasher that I have that is rated at 2 amp minimum . It all worked (front turn signal, dash light and original non led rear turn signal) until I added the rear led turn signal and then it was to low for even the new 2 wire led flashers I bought . ( as soon as I put 1 led in the circuit the original flasher quit working)

  20. #20
    CB750 Addict Dave's Avatar
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    Don't forget the brake lamp!

    The flashing brake lamp increases your visibility more then anything else. It fit right in my stock tail light. IIRC, it's only 3mm taller then an incandescent 1157.
    96% of the time I edit my replies so check back for updates if it isn't at least an hour old

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