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LED Tail Light Conversion

Charging System, Wiring, Lighting
Gunner_CAF
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Posts: 316
Joined: Sun Oct 12, 2008 5:28 pm
Location: Wisconsin, USA

LED Tail Light Conversion

Post by Gunner_CAF » Sun Jun 14, 2009 9:41 pm

In an attempt to reduce load on the charging system, I have converted the tail lights to LED. The problem with some 1157 plug in conversions are the LEDs are directional and direct the light to the back. The tail light on a motorcycle also lights the license plate so you need some of this light to be directed down.

If you search eBay, there are a lot of LEDs available. They are many different sizes, some are red only, some direct light to the sides. It's hard to tell what would work well unless you buy some and see.

I found some at a local auto parts store and decided to try them. This 1157 LED replacement is all Red and directs all the light to the back. I also found a flat array of white LEDs made for auto dome light conversion. I used this for the license plate light.

The 1157 LED replacement has a socket base and is easy to change out. To add the white light took a little more work. I drilled a small hole in the tail light back plate so I could run the two wires to the back side where the tail light wiring is located. I soldered the LEDs red lead to the white wire on the tail light, the black to ground. LEDs only work one direction, so you need to get the polarity right.

I used the double sided tape on the back of the flat LED array and put it on the inside top of the Lens pointing down. The LED came with some small wire plug so it can be detached when the lens is removed. I put it all back together and tested it. There are pictures below.

In the daylight, I see little difference between the old incandescent light and the new LED. It gets noticeably brighter when the brake is pressed. In the dark, it lights the license plate quite well. When I compare it to my newer Yamaha, it looks to be the same brightness and the license plate light looks a bit whiter.

I think it looks good, but the real reason I did this is to reduce a little more load from the charging system. I will see if I notice any difference over the next week.

Gunner
Attachments
In the dark.  Just the plate numbers have been modified in the picture.
In the dark. Just the plate numbers have been modified in the picture.
Brake Light - Day
Brake Light - Day
Running Lights - Day
Running Lights - Day
Licence Plate light taped to the top of the tail lens.
Licence Plate light taped to the top of the tail lens.
Both lights connected.
Both lights connected.

Goodysnap
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Posts: 456
Joined: Mon Oct 06, 2008 7:25 pm
Location: Lansing , Michigan

Post by Goodysnap » Mon Jun 15, 2009 6:30 am

Thanks for sharing . Great idea. Whatever you can do to save an amp, Right?
64' CB77
65' CB160

Gunner_CAF
honda305.com Member
Posts: 316
Joined: Sun Oct 12, 2008 5:28 pm
Location: Wisconsin, USA

Post by Gunner_CAF » Mon Jun 15, 2009 11:37 pm

Goodysnap wrote:Thanks for sharing . Great idea. Whatever you can do to save an amp, Right?


Right. With a full charge on the battery, the battery will not have enough charge to turn the starter after several hours of riding around town. It's good for about 6 or 7 starts before I need to use the kick start. I hope by shaving off the power feeding the tail light, it will have more power to charge the battery.

Gunner

Spargett
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Joined: Wed Jun 18, 2008 10:19 pm
Location: Los Angeles, CA

Post by Spargett » Tue Jun 16, 2009 4:52 am

Please let us know what effect it ends up having. Thanks for sharing.
Gunner_CAF wrote:Right. With a full charge on the battery, the battery will not have enough charge to turn the starter after several hours of riding around town. It's good for about 6 or 7 starts before I need to use the kick start. I hope by shaving off the power feeding the tail light, it will have more power to charge the battery.

Gunner

Vince Lupo
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Joined: Wed May 04, 2005 7:17 am

Post by Vince Lupo » Tue Jun 16, 2009 4:52 am

So what's causing your charging system to not enable you to use the starter after several hours of riding? Have you checked all the components to make sure they're all good? What is your charging system putting out, by the way?

I had gone through the whole charging system dilemma a couple of years ago with my '66 SuperHawk, and eventually replaced the rotor with an earlier version (without the 'L' on it). They supposedly put out more power than the the 'later' ones. That bit of advice was courtesy of our good friend, Mr. L. Mouse, and it has been a big help. As well, I switched over to one of Retro Bike's rectifiers, and I'm using a PowerSonic gel battery. No problems with the charging system at all when riding with the lights on all day, though your conversion to an LED rear light sounds very enticing.

Gunner_CAF
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Posts: 316
Joined: Sun Oct 12, 2008 5:28 pm
Location: Wisconsin, USA

Post by Gunner_CAF » Tue Jun 16, 2009 11:44 pm

Vince Lupo wrote:So what's causing your charging system to not enable you to use the starter after several hours of riding? Have you checked all the components to make sure they're all good? What is your charging system putting out, by the way?

I had gone through the whole charging system dilemma a couple of years ago with my '66 SuperHawk, and eventually replaced the rotor with an earlier version (without the 'L' on it). They supposedly put out more power than the the 'later' ones. That bit of advice was courtesy of our good friend, Mr. L. Mouse, and it has been a big help. As well, I switched over to one of Retro Bike's rectifiers, and I'm using a PowerSonic gel battery. No problems with the charging system at all when riding with the lights on all day, though your conversion to an LED rear light sounds very enticing.
A low battery causes the starter to not work. I put the volt meter on the battery a while back and it will charge with the lights off. I didn't record the readings.

I have a new standard lead acid battery and a Retro Bike's rectifier. Thanks for the tip on the rotor!

Gunner

Vince Lupo
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Joined: Wed May 04, 2005 7:17 am

Post by Vince Lupo » Wed Jun 17, 2009 3:02 am

It wouldn't surprise me to know that one of the main problems with these bikes' charging woes was attributed to a de-magnetized (or at least reduced magnetism) rotor. I looked into having my original rotor 're-magnetized' a few years ago and it couldn't be done. Don't know if the stator's effectiveness can be increased with additional windings - I'm sure then you'd get into clearance issues. And simply replacing the rotor with an NOS one might not solve the problem - I mean, if they've been stored for years alongside other rotors, they could actually de-magnetize each other.

I understood that running the bike with the lights on enables the 'third phase' of the charging system, and actually boosts the charging system's output - you know, you read about that little trick involving the high-low beam switch in the middle position.....think that might only work with the earlier bikes, though.

Funny about all this - I had an '81 CB900f back in the 1980's and it had a marginal charging system too....is that some Honda thing???

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