Friday, February 26, 2010

Fixing Molly, a 1981 Honda CX500c

Here are pictures of all the things done to Molly to get her to work well.

When we brought the bike home, the first thing we did was change the handlebars. CX500 Customs have hangar handlebars like cruisers. The hand position is really uncomfortable and can cause tendinitis. Besides, I have a fractured forefinger (hairline probably), and during the ride home, whenever possible I had to shake the pins and needles from my hand. Not good positioning.

Me on Molly, a 1981 Honda CX500c, testing different handlebarsTesting different handlebars

The right blinker wasn't working and the battery wasn't holding its charge, so Jason tested the rectifier-- that was good-- and I removed the headlamp to look at the wiring. What a mess!

Messy wiresThese wires were hanging out the back of the headlight fixture, tangled in a ball wrapped in electrical tape.

Someone had spliced in extra wires to attach flasher relays. A bike only needs one flasher relay connected in series to the switch. But this bike had two flashers wired in after the switch. The right flasher was wired incorrectly, hence non-working. Plus, hot wires were exposed, which means the power was going directly to ground. That's why the battery was discharging. Evidence of the discharge showed up on the starter relay near the battery, which was sprayed with dried battery acid.

I untangled the ball, removing connections that were done by a hack, and started pulling wires through the headlamp fixture, where they belong. There were lots of cut wires!

Pulling wiresUntangled!

After getting all the wires through, I called it a day. Next was retrieving the wiring diagram to rewire and get everything working properly.

All the wires pulled through the fixtureIt already looks better.

Since the harness is different from the original, I had to go by several wiring diagrams in order to understand which wire went where. Unfortunately, each diagram had a different key. One diagram used the letter "B" for Black. On another plan, it was Blue. Aw, geez. I had to make lots of notes.

Original Honda CX500 wiring diagramThis is the original Honda CX500 wiring diagram before the Custom came out. This diagram helped most. Some of the differences were drawn in. All the dots that are circled is where wires needed reconnecting. If you double click on the picture, you can see it bigger.

This next diagram is the addendum to to the Honda manual. Unlike the harness Molly has, the following diagram has only one black wire in the harness. Molly's harness has two black wires running through. This explains why the previous electrical hacker cut so many wires trying to make it work.

Honda CX500 wiring addendumThis is the addendum to the wiring diagram with notes for the different models. I circled the power line connectors to figure out why Molly's lights weren't working properly. That didn't help much. Though, it was from remembering this diagram that I realized that that circuit simply wasn't getting power.

Did I mention I made lots of notes?

My sketch of the blinker circuitSince the existing diagrams didn't match, I made my own diagram to figure out the problem.

The Haynes Honda CX500 wiring diagramThis is Haynes' Honda CX500 wiring diagram. I used this to figure out which power line needed a splice. See where it says "4 way connector"? That's where the additional brake lights are going to go after reducing blinker power.

To get the blinkers working, I used the gray and black wires in the harness, unlike the original CX500 manual, which says they run through the headlight fixture.

Flasher relays are polarized. You have to match the correct terminal to the power source. In this case, the black wire goes to the positive side of the relay (I think. I'm not sure because this relay has an "X" instead of a "+"). The gray wire returns to the lights via the switch. In my sketch, I drew two power sources: one through a fuse, the other from "power." I'm not sure why I drew it that way. Probably because of all the diagrams I was trying to reference. I ended up going through a fuse, because of this diagram I found on a website.

Someone's flasher diagramIt looks like the person who drew this might be an engineer. I think I'll trust this and go through a fuse.

There was a spare brown wire, probably for cops to attach a siren or something. I used this for the blinkers since this line only powered the lights in the tachometer and speedometer. If I ever put in something like handwarmers, I'll reroute the blinkers to the main power line and install a heating element through that fuse (maybe). Besides, my new blinkers will use just a little power and will need a thermistor or some other resistor to keep them from shorting. But, hey, if you know better what to do, please comment!

Relocated flasher relayTurn signals only need one flasher relay. The switch controls which lights are connected to it. (That's soldering flux in my left hand. It's all Radio Shack had for flux.)

After testing the relay, I had to clean up some of the connections, and tighten others. Once all the connections were clean and insulated, I put the wires together for the headlight to go back on. The 7-volt regulator (not the same as the rectifier/regulator combo unit) sits outside the fixture. Wires were wrapped and pulled out to make space inside the fixture. In the end, all the original plastic connectors, and newly soldered connections were inside the fixture.

Organized wires in the headlight fixtureThe wires reconnected and reorganized! It's not advised to use those blue connectors permanently, by the way. But making sure everything worked, it sure was handy having them. When I change the bulbs to LEDs, I'll solder and heat shrink the connections.

She works! (Picture to come.)

1981 Honda CX500c wiring

She works! Two nights ago, after getting home from the shop, I looked at the Honda manual's electrical diagram thinking about why the front brake, headlight, and running lights work, but not the rear brake, turn signals, oil and clutch lights.

The problem with figuring it out was that the harness did not match the model bike I worked on, and it wasn't the same as any of the 3 diagrams I used. So, I had to really think about how power is routed. Fortunately, once I matched the connectors that go in the headlamp fixture to the ones in the diagram, I could see that only 4 or 5 wires were different. (When we bought the bike, the wires were in a tangled ball outside the fixture.) Maybe there were more mismatched wires, but there were only a few that mattered.

Power for the lights must come through the ignition switch. The lights I mentioned-- front brake, headlight, and running lights-- did. The rest were powered by...? That was the problem. Those were connected directly to the voltage regulator attached to the rectifier. But power doesn't come through there unless the engine is running. The oil and clutch lights must come on before the engine is started. So where was the power going to come from? It also had to come from the ignition switch.

The original Honda plan has a black wire that appears to end on a connector. That connector was obviously different from what I had on the bike. Sure enough, that black wire on the plan was on the same circuit as all those non-working lights. The original connector probably had connection to power in it. But my connector is different; it doesn't have that connection.

I wanted to put these lights on a different circuit from the front brake so that in case one circuit went bad the other circuit would still have a brake light. This second circuit also had to come from a 10amp sub-fuse. The headlamp needs its own fuse since it uses the most power at about 40 watts on low beam. The brake light is 27 watts, each turn signal, 23W. The lights on the indicator panel use 3-4 watts each.

I had to find a battery-powered wire to splice into. Fortunately, on this harness, there was a spare brown wire routed via the ignition switch from a non-headlamp fuse. The only other thing this circuit powered was the speedometer/tachometer night lights. I connected this brown wire to a spliced-in black wire from the turn signal circuit.

Unfortunately, with everything wired, too much power was needed to make everything work through one sub-fuse. I ended up disconnecting the front running lights (turn signal lights that stay on when not indicating a turn) in order to have enough power to run the essentials-- brake light, running tail light, oil and clutch indicators, and turn signals.

I have to say, I really enjoyed working on this project. Moreso than other kinds of projects. Writing my book wasn't even as fun.

Now that I can get the bike inspected, next electrical step is to replace the turn signals for LEDs. They will draw less power. Then I'll be able to reconnect the front running lights. (I'll swap those, too.) I also want to add 2 more brake lights to make a braking triangle. This could potentially prevent being rear-ended by absent-minded cagers.

Can't wait to ride! Snow, go away!

Monday, February 22, 2010

Wire gauge

So, I have to replace some wires on old Molly. She's a 1981 Honda CX500c. It looks like someone replaced the entire wire harness, because on her model, the flasher relay should be located in the headlamp fixture, but the gray wire to connect it runs to the back like in newer Hondas. Some bloke jimmied in a couple relays in the front and miswired the right blinker so that no power was getting through to the switch.

Thank goodness my daddy, former electrical engineer, passed down his engineering aptitude DNA to me. :)

Oh, so, I was going to share this website: It tells you what gauge wire to use. On this custom, currents can get past 20 amps, so I'm getting 14 gauge. I hope the other wires are 14 also. *sigh*

Bike upgrade!

It's been a while since blogging about Georgia. Well, that's because she's been in the shop. Jason and I decided we'd fix her ourselves. We changed the chain and the rear sprocket, which was bent when hit by a car. The tire has been balanced, and Jason took her for a spin. I haven't ridden her, though, because I was afraid to ride her after an amateur balanced her tire.

The rectifier I installed works. Her battery's been charging just fine. I wrapped it in heat resistant tape (up to 500 degrees F) and bolted/grounded it to the frame where the old rectifier was. I'll put rectifier pics up later.

Anyway, Georgia was too small for me to ride anyway. I couldn't get her over 55 mph over the Manhattan Bridge, the way I ride to get home from the city after work. And I certainly was unable to pass a truck safely, so Jason decided I needed a bigger bike.

Here she is! Her name is Molly. Ain't she a beaut?

We got her yesterday. The owner thought the rectifier was bad. We test it, and it's fine. BUT the wiring is a mess. The battery was probably discharging through all the exposed copper throughout. This is what it looked like behind the headlamp:

I'm gonna work on her today. Clean her up nice. :)