Timberwoof’s Honda CB-1 Page


Wrenching the CB-1

The CB-1's tool kit contains just about everything you need to do minor maintenance on the bike:
  • 8-, 10-, 12-, 14- and 24mm wrenches
  • three Allen wrenches
  • spark plug wrench
  • hook spanner to adjust rear shock preload
  • pliers
    It helps to add one of those little screwdrivers with the double-ended shaft.
    I also keep a pair of latex exam gloves in the toolkit: Nothing works better to keep your hands clean while you're working on the bike.
    (When you're done with them, grab the right glove by its cuff, pull it off, and hold it in your left hand. Then, with your right hand, grab the cuff of the left glove, pull it off, and let it turn inside-out with the right glove inside it. You're left with an inside out glove with another glove in it and all the grease on the inside.)
    The CB1 is running 8500 rpms at 75 mph. Even though the redline is 13500, the mechanic that I had checked it out seems to think that extended periods at this speed will eat up the motor. I tend to disagree, though. It's only at 60% capacity at that speed. What's your (and others') opinion on this?
    If you calculate the stroke of this little engine, you'll see that it's traveling at the same speed up and down the bore as as bigger, slower engines. If you are going to do a lot of freeway riding, you should probably get cooler plugs (NGK CR9EH-9 for extended high-speed running, NGK CR8EH-9 standard).
    I run Regular (87 Octane) in my stock CB-1. I've never heard it knock or ping, so I don't see the need to waste money on higher-octane gas.
    Oil is crucial to any motorcycle: I'm changing mine every 2500 miles, filter every other time. As long as it's neither icky black sludge when it comes out nor brand-new golden honey, the interval is right. (Don't want to change it too often because that's a waste of money.) The clutch and transmission share the engine oil...
    Drive Chain
    I wouldn't mess with the gear ratios. The Honda engineers worked their butts off to find the optimum ratios ... Make it too tall and you won't have as much torque for accelerating or climbing hills. Make it too short and it will go like a bat out of hell but be too close to the top end on the freeway.
    To test the chain tension, put the CB-1 on its sidestand and shift it into neutral. Measure the free play halfway between the sprockets on the lower chain run. That's right where the swingarm flattens out.
    Put the 24mm wrench over the axle nut on the right side of the rear wheel so the wrench extends straight back. The tool kit contains a piece of flattened pipe. Slip that over the end of the wrench and stand on it with one foot: that should loosen it right up.
    At the end of the trailing arms are a single stud with two nuts each. Put a 14mm wrench over the big nut and a 12mm over the small one. Open the small nut and back it off just a few turns. Turn the 14mm nuts both in the same direction and the same amount at a time. When the chain is close to the right tension, small changes in the nut create large changes in chain tension, so only turn the nuts 1/6th at a time between measurements. The free play should be between 15 and 25mm (5/8 to 1 inch).
    While you're at it, make sure the back wheel is aligned properly. Place a strait-edge on the rear sprocket so that it is close to parallel with the chain. By turning the right nut, adjust the rear wheel so that the distance from the strait-edge to the chain is the same at the front and the back.
    As a final check, sit on the bike, lean over, and test the chain tension. It will tighten up, but it should not get too tight now. If, when pushing the bike around, you hear a lot of chain noise or feel a lot of chain vibration, then the chain is too tight.
    If the rider is not very heavy, the bike probably doesn't need a lot of spring preload on the rear shock. It's worthwhile experimenting with the preload: reducing it will do two things. First, it will make for a cushier ride over interstate superslabs. Second, it will lower the ride height a tad, perhaps the same about that smaller tires would, and probably without upsetting the steering.
    Remove the seat. Take the wrench from the tool kit that has an elongated C-shaped end and slip the flattened pipe over its other end. Use the hook spanner you just made to dial a different position on the rear shock. I weigh 125# and I've got mine set at 3. It was at 5 when I got it. Make sure the tires are at the right pressure. If it feels squirmy over pavement grooves, add a psi at a time until it goes away.
    The mechanic recommended low profile tires (to lower the bike so my girlfriend's feet can rest flat on the the ground) and then putting on a new front and rear chain gear to gear it up and even overcompensate. Any opinions on this? I won't do it for a while though, as I am not rich, and the tires on it are almost new.
    The CB-1 is finicky with tire selection and different riders rave about different tires. I have Metzeler ME33 in front, ME55 in back, and they're a bit too big: that makes it really sensitive to rear tire pressure. The standard front size is 110/70-17 54H; the standard rear is 140/70-17 66H.
    When the rubber hoses get old, they expand when you apply the brakes. This wastes effort and reduces brake feel. So I highly recommend a steel-braided brake hose for the front brakes. That will make the bike stop surer and with better feel: the brake lever is firmer and not at all spongy. Better yet, since you won't spend so much effort expanding the rubber brake hose, it takes less squeeze to stop the bike.
    When I bought my CB-1 in february of 1996 it had the factory original battery. Seven- or eight-year-old batteries just don't hold a charge very well. I bought the cheap Yuasa battery to replace it and had to replace that within a year. But the folks where I got it were nice about it. They pro-rated the cost of the battery against the warranty and applied that to the expensive Yuasa. That one, with careful monitoring and an occasional night on the charger, has shown no sign of giving up. If I had a garage to keep my motorcycle in, I'd give it a little plug for the battery and just plug it in to a battery tender whenever it was at home.
    Here are some voltage measurements I made after the bike hadn't been ridden for about a week:
  • 12.8V ignition off.
  • 12.0V ignition on.
  • 9.5V while starting.
    There is a voltage below which the engine will just not catch. Either the engine is just turning over too slowly or the ignition system's working voltage can't raise a spark, but once you're past that point, the only solution is a push-start or a jump-start. If you have a sufficient hill, you can push-start the bike on a weak battery ... just make sure you don't letthe engine die at the bottom of the hill!
    When I got my CB-1, it had a Tsunami fairing. I removed it once to see what the bike looks and rides like without it -- and put it right back on. A few months after I got the bike, I dropped it and broke the Tsunami. I replaced it with a Lockhart-Philips cafe fairing. It's cheap and required some cutting to make it fit, but it doesn't look too hideous and it works better than nothing.
    If you want to put an LP fairing on your CB-1, be prepared for some corrective surgery. You have to cut a channel for the turn signal stalks and make clearance for the front brake fluid reservoir and the choke.
    The CB-1 weighs only 375 lbs dry. With fuel and a rider, that's about 550 lbs. The bike is thus sensitive to side winds ... but don't worry. On the freeway, this is not a problem. Just get into a good racer's tuck, loosen up on the handle bars, and let the bike lean how it wants to. Gusts will push you around a bit, but if you stay in the middle of your lane and keep loose, the bike will do the right thing. There's actually an advantage to this: cagers seem to notice that you're weaving about all over the place, so they give you extra room.
    Grooved Pavement, Railroad Tracks, and other Irritations
    Like any motorcycle, the CB-1 is sensitive to edge traps. But its tires are wide enough that grooved pavement, railroad tracks, and grilles over subway openings aren't much of a problem. On groovy pavement, do the same thing as for wind: loosen your grip on the handlebars. Train tracks that run along the pavement, as the Muni tracks do in San Francisco, aren't the deadly traps they are for bicycles. Do try to avoid them in wet weather, but don't be paranoid about it.
    Easy Modifications
    The taillight is extended back about 3 inches by a plastic bracket under the rear skirt. Remove the seat, unbolt the skirt, and take that bracket out. The taillight fits snug in there and looks much better. There are, however, two drawbacks. First, the reflectors on the side of the taillight are now partially hidden by the skirt. Second, the license plate is not illuminated as well. You can fix the second problem by bolting the license plate directly to the fender.

    In this picture you can see the taillight retracted into the rear cowl. I also remounted the license plate directly on the rear fender right under the taillight and added another brake light below that. The white stripes on the front fork and the rear trailing link are reflective tape from a marine supply store. They and the license plate are illuminated here by the flash from the camera.
    The CB-1 has 41mm fork tubes, which easily receive aftermarket clip-on handlebars. For a while I tried Lockhart-Philips clip-ons. They are lower and put you in a deeper crouch, but you end up with more strain in the rest of your body. I have photographs of stock and LP clip-ons.

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