July 2002, updated
I just finished my first modification --adding two driving headlights.
Photos are here.
I encountered a number of problems which I'll explain so that you can avoid them.
This my first motorcycle modification, chosen for safety reasons. I wanted these extra lights on ALL the time to help the numerous "blind" auto drivers see me coming before they pull out into my path.
When I first starting riding my Rebel a car pulled out in front of me about twice every week or so. (Drivers in big cities are very aggressive!) Since adding these lights no one has pulled out in front of me.
Update April 2003: A taxi driver pulled out in front of me, but he wasn't even looking in my direction. If I'd been driving a bus he still wouldn't have seen me, and I probably couldn't have avoided hitting him. Always watch out for taxis no matter what you're driving!
The Lights I Bought
I chose these inexpensive $35 lights which JC Whitney advertised as motorcycle lights
and these $8 fork mounts
I wasn't sure about mixing these square lights with the round headlamp, but I like the look. They are fairly large and they are very visible to other traffic, which is the point. The fork mounts have a nice chrome finish, but they do allow the lights to vibrate slightly more than I'd like at stops.
I've made these lights work, as you can see in my photos above, but frankly I do not recommend them. It turns out they are actually made for cars --the rear mounting metal is an off-color (see detail photos), and the wattage of the bulbs is much too high (55 watts each) for the Rebel.
What I did not know at the time that I bought them is that the Honda Rebel 250's electric system does not have the capacity to power them continuously as running lights.
Add-On Wattage Limitations
In the Yahoo Rebel Discussion Group, David Overstreet posted the electrical specifications for 1996-2002 Rebels which I repost here. The main thing to understand is that the Rebel 250 has an alternator (generator) which recharges the battery when the motorcycle is running as well as powering the lights and other electrical needs. That alternator is rated at 190 watts output when running the engine at 5000 rpm, less when running slower.
The headlight is always on when the Rebel is running, and uses 55 watts of that 190 watts of power. The tail lights, tag light and indicator lamps also use a little more of that power. The brake light and turn signals use some more whenever they light up. And finally, the spark plugs need some uncertain amount of power.
My best 'guess-timate' from the specs in the table is that the Rebel's lights burn about 75 watts during normal driving. That leaves about 115 watts for battery recharging and spark plug firing from the alternator's 190 (or less) watts.
Each of the add-on headlights I bought is 55 watts --a total extra load of 110 watts. That would leave only 5 watts for battery charging and other! The battery normally uses about 8 to 36 watts during recharge, depending on what's available (for a quick or slower recharge).
Bottom line: you may be stretching your luck by adding anything over 70 watts. If you search you can find add-on lights that are 35 watts each (70 total). I had to modify my new add-on lights later to reduce their wattage - 110 is too high!
Regardless what lights you buy, you'll need to connect wires to them.
To connect my new lights, I first tapped into the headlight wiring --on the low beam side (it was easy to locate in the patch panel above the headlight). After a few hours though, they burned out one of the 10 amp fuses behind the battery. Why? 55 watts + 110 watts = 165 watts. At 12 volts, that's 165/12 = 13.75 amps --a little too much current for a 10 amp fuse. Even with two smaller 35 watt bulbs, you'd be over the 10 amp fuse limit of the headlight circuit and need to run a separate cable from the battery (plus an on/off switch if you want to allow full battery power to the starter when cranking up).
After learning about the electrical capacity of the Rebel, I modified the headlights I bought. I replaced the bulb sockets and bulbs with 20 watt (each) halogens which I picked up at a hardware store. They don't light up the road at night like searchlights, but they are plenty bright enough to be seen by other drivers day or night, which is the whole point of this modification. The original headlight still lights the road up fine.
As originally wired (tied into the headlight wiring), these extra lights would get power only when the headlight was on Low beam. Switch to Hi beam and they would turn off.
After studying a wiring diagram of the Rebel (the very last one in the back of a Clymer book labeled for 1996-1997 CMX250C models) I saw that I could tie my new lights (at 40 watts) into the wires in the patch panel above the headlight at a different point so that the lights would stay on regardless of whether it was on Hi beam or Low Beam.
The connection point needed is the BLUE+WHITE striped wire --it comes from the starter button on the left (looking at the headlight) and goes to the Hi/Low beam switch on the handle bar. This power gets cut off when you press the starter button, so no extra on/off switch is needed unless you want to be able to turn these extra lights off sometimes. Have you ever noticed that your headlight goes OFF while you press the starter button?
After six months of normal driving I have had no problems. The battery has been getting a full recharge, even with the extra electric load of the new "running" lights constantly powered on. And a number of times I'm very sure they have made a difference in making me more visible to other drivers on the road.