Sometimes the easiest maintenance chores are the ones most frequently overlooked. Case in point: we frequently see some of the newest, hottest bikes sporting limp chains. Since the drive chain is responsible for getting all that horsepower from the engine to the rubber, riders who want to transfer every last bit of what those hydrocarbons are offering to the ground should pay attention to the chain. Need we mention that an improperly adjusted chain-or one in bad condition-can cause unpleasant things to happen to both bike and rider? The key is to perform the maintenance on schedule and inspect the chain for stuck links or obvious signs of wear.
1. Cleaning the chain and sprockets is the best way to start. Motorex (914/ 228-0145) makes a nifty chain cleaner that works well and won't harm O-rings. WD40 (619/275-1400; www.WD40.com) will also work in a pinch. Put your bike up on its center stand or use a rear stand. Place newspapers or a piece of cardboard under your bike to catch overspray. After applying a liberal coat of chain cleaner on the chain, let it soak for a few minutes to loosen up any mung. Then, using a rag that's been folded over a few times, hold it under the chain while turning the rear wheel by hand. Refold the rag and carefully repeat on the top of the chain and its sides. Resist the temptation to idle the engine in first gear to speed up the cleaning process.
2. Most manufacturers recommend a chain's adjustment be checked every 500 to 700 miles. Unless you're racing, doing wheelies and/or burnouts or other activities that stress the drive train, you shouldn't need to adjust your bike's chain at every inspection. When you do, though, check the chain for signs of wear by pulling it straight back from the rearmost point on the rear sprocket. If more than half of the sprocket's tooth becomes visible, it's time to go to your local bike shop for a new chain. Consider replacing both sprockets at the same time since worn ones will only damage your shiny new chain.
3. To measure the chain slack, find the midpoint between the countershaft and rear sprockets. Press down on the chain slightly to make sure it's at its lowest point. Align a tape measure between two rivets on a link. While holding the tape measure steady, push the chain up as far as it will go. Read the measurement between the same two rivets. Now, consult the owner's manual for the range of proper adjustment. Even if the measurement checks out OK, turn the rear wheel and measure the chain in two or three more places to make sure it doesn't have any stuck links or uneven stretching. If the chain has dramatically looser or tighter sections, you will need to replace it.
4. The two most common causes of premature chain wear are an improperly aligned rear wheel and worn sprockets. Although both are easy to remedy, a bit of investigative work is required. Look at the teeth on the sprockets. Have they become curved like cresting waves? Are the sides of the teeth worn? A yes answer for either question says that a sprocket's days are history. As a rule, replace both of your bike's sprockets and the chain at the same time. If the sides of the sprockets are worn, the rear wheel is out of alignment.
5. Although your bike's rear wheel may seem to be in-line-according to the stamped lines on the swingarm or adjusters-the factory markings are notoriously inaccurate. For years, savvy (and thrifty) riders have used the "string method" of verifying that their wheels are aligned correctly. You need a string a little longer than twice the length of your bike, a rear stand and an assistant. Find the center of the string and wrap it once around the leading edge of your front tire, an inch or so below the axle. Now, pull one end of the string on either side of the bike to the rear. Lie down on your stomach and pull the string taut at both ends. Have your assistant make sure that the string is lined up evenly off both sides of the front tire. When the string is pulled tight from the front to rear tire, it leaves a slight gap at the back of the front tire because the rear tire is wider. While you sight down the string, have your assistant adjust the wheel so the gaps between the string and the rear edge of the front tire are equal on both sides. Keep your hands steady so the string only lightly touches the front of the rear tire. Compare the gaps on either side at the back of the rear tire; If they aren't equivalent, the adjuster on the side that is closer to the string will need to be tightened.
6. For those who prefer a high-tech approach, several aftermarket alignment tools are available. One model even uses a laser to keep things aligned.
7. If your bike's chain adjusters have locknuts, loosen them while holding the adjusters in position with a wrench. Loosen the axle nut but not so far that the wheel will slide around in the swingarm. If your wheel is out of alignment, turn the adjuster (no more than an eighth of a turn) on the side of the axle that was too far forward (i.e. had the narrowest gap with the string). Turn adjusters in front of the axle counterclockwise to tighten; adjusters behind the axle, clockwise. Re-measure the wheel alignment.
8. If your bike's chain adjusters have locknuts, loosen them while holding the adjusters in position with a wrench. Loosen the axle nut but not so far that the wheel will slide around in the swingarm. If your wheel is out of alignment, turn the adjuster (no more than an eighth of a turn) on the side of the axle that was too far forward (i.e. had the narrowest gap with the string). Turn adjusters in front of the axle counterclockwise to tighten; adjusters behind the axle, clockwise. Re-measure the wheel alignment.
9. Once your chain has the proper slack, torque the axle nut to your bike's factory spec while keeping the wheel pressed forward. (You may have to call your local shop if you don't have a repair manual.) Re-check the wheel's alignment, give both adjusters a slight turn to put pressure on them and tighten the locknuts. If your axle nut requires a cotter pin, install a fresh one. Finish up by lubing your chain and wiping off the excess lubricant.
How & Why
Although no specialized tools are required for adjusting your chain, we recommend that you use a torque wrench on the axle nut. (Your bike's tool kit has the necessary parts if you're on the road.) Of course, a factory manual is always helpful, but in this case, the owner's manual will suffice. A chain adjustment on our VTR needed a ratchet, a rear stand, 22mm and 24mm sockets, string (or a wheel alignment tool), a tape measure, a torque wrench and an 8mm wrench.
This article was originally published in the October 2000 issue of Sport Rider. For more tech tips, visit the Tech page.