Chain and Sprocket Service
Chains are widely used on motorcycles because they are simple, efficient and relatively inexpensive. But they still need regular maintenance, including lubrication, adjustment, and eventually replacement. A well cared for chain may last 15,000 miles or more on a street bike, but if abused or neglected, its service life can be severely shortened. When a chain fails it can severely damage the engine case or even get wrapped up in the wheel and sprocket, locking the rear wheel (don't ask me how I know).
Two major chain types are O-ring and non-O-ring chains (although you may hear of similar designs such as “X-rings,” which are a variant of O-ring). The O-ring chains have small rubber O-rings between the side plates, which hold in lubricants. This design typically lasts much longer than non-O-ring chains, but also costs considerably more. Either type needs to be kept clean to prevent a buildup of grit, which accelerates wear, and the links require just the right amount of lubrication.
In normal riding conditions street riders should lube O-ring chains about every 500 miles or so, but consult the owner's manual for specific recommendations. If you ride in rain, mud, silt, dust, or other tough conditions, or have a non-O-ring chain, intervals should be sooner. When washing a motorcycle, avoid directing water on the chain and be sure to lube your chain right after washing the bike to prevent rust.
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Avoid using avoid harsh or flammable solvents such as gasoline, which can ruin the O-rings or cause a fire. Rather, use a cleaner such as PJ1 Super Cleaner or Bel Ray Chain Cleaner. A handy cleaning tool is the Simple Solutions Grunge Brush, which cleans well and is easier to use than a rag and small wire brush.
Chain lube comes in a variety of types and brands, and many riders have their individual favorites. Waxy lubes seem to stick well, instead of slinging off. Most of the heavier lubes seem to last longer, but often make a mess of the wheel rim and surrounding area. It may take some experimentation to find the one best suited to you.
Lube the chain while it’s still warm after riding, but never with the engine running. Maintenance is much easier if your motorcycle has a centerstand. Position it on the centerstand and place the transmission in neutral to allow the rear wheel to be turned by hand. If your bike doesn’t have a centerstand, roll it forward a short way each time to access another section of the chain. Apply the lubricant evenly; most spray cans come with tiny straws that make it easier to direct the flow directly onto the chain.
If a chain is too loose it may grind on the swingarm or even jump sprockets. If a chain is too tight it may damage the countershaft and bearings, or even break. Owner's and shop manuals provide slack measurements and adjusting procedures. If you don’t have a manual handy, a rule of thumb is about 3/4 to 1 1/4 inches of vertical slack, measured midway between sprockets.
To adjust chain tension, typically a cotter pin is removed and then the axle nut is loosened. Next, either adjusting bolts are shortened or lengthened (most have locknuts that must be loosened first, and then re-tightened after adjustment), or adjusting cams are turned, until the proper slack is achieved. Old worn chains wear unevenly and develop loose and tight sections, so slack varies. Therefore, it’s important to check slack several times in different sections of the chain, as you rotate the wheel and set it where the chain is at its tightest point. Always recheck slack after tightening because the setting might vary.
Most swingarms have alignment marks on each side to make it easier to keep the wheel straight during chain adjustment, but there are other ways to check axle alignment. Motion Pro makes a useful chain-alignment tool. You can also use a tape measure and check the distance from axle the centerline to the swingarm pivot bolt centerline on each side.
Motorcycle chains come in various sizes, and are numbered (e.g., 520, 530, etc.) This has to do with the width and pitch or distance between links. Chains specifications also list tensile strength rating; the higher the rating, the stronger and (likely) the longer it will last. The other vital specification is the number of links. Make sure you get a chain that meets all specifications for the bike.
Many motorcycles come from the factory with continuous chains that are all riveted together and don't have a master link. Replacement chains are sold either with:
- Master links with clips (which can be installed without special tools)
- With a master link which must be riveted
- Chains with no open links
In general, high-horsepower bikes only come with either a link that must be riveted (because they’re stronger), or a one-piece chain without an open link, which makes it necessary to remove the swingarm for replacement.
If you find that a replacement chain is too long, links can be removed. The most expedient way to do this (besides taking it to a shop) is to grind the peened over end of a rivet off, on the pin you want to remove. After the “head” is ground off, take a small pin punch and a small hammer and drive the pin through the link and out the other side. If you plan to service chains regularly, consider buying a chain breaker/riveting tool. Emgo, Motion Pro and RK Chain, among others, all make them and these make the job much easier.
To install a new chain that has a clip-type master link, have the wheel off the ground and transmission in neutral. Remove the old master clip and link, and connect one end of the new chain with the old chain using a new link. Slowly feed the new chain from rear to front along the top, onto the front sprocket. Pull the new chain with the old one until both ends meet at the upper rear portion of the rear sprocket (the axle adjusters needs to be loosened to provide slack.) Insert the master link through both new ends, make sure the O-rings are in place and install the side plate and clip. Sometimes it is necessary to compress the O-rings with a special tool; a needle nose Vise Grip can be used in a pinch. With rivet-type master links, follow the instructions that come with the tool.
Generally, when chains are replaced, the sprockets should be changed too. When sprockets wear out their teeth become sharper and eventually they become somewhat hook shaped instead of symetrical, which accelerates chain wear. To check for wear, pull straight back on the chain at the middle of the rear sprocket. If the chain pulls out enough to reveal sprocket teeth, it's quite worn. If the chain won't pull away from the sprocket, it's probably OK. Chain links that start to kink and don't move readily (even after lubing) also indicate replacement is due.
Changing a front sprocket usually requires removing a sprocket cover (and the chain). Typically, a metal locking tab must be bent away from the retaining nut. With the engine in first gear, the nut is removed with an impact wrench and reinstalled the same way. It should be tightened to the specified torque, and the tab, cover and chain installed.
Changing a rear sprocket usually requires chain and rear wheel removal. Many sprockets fit onto a cushioned hub, and you have to unbolt the sprocket from its mounting. Install a new sprocket and tighten securely. Reinstall the sprocket assembly onto the hub and wheel, install the wheel and axle and adjust the chain.
Always follow the procedures in the service manual. When work is completed, visually inspect it to verify everything is properly assembled and tightened. Push the bike and verify free proper movement and test the brakes. Ride slowly during the initial test ride and reinspect all work. If you don't feel confident about how to service your motorcycle, take it to a professional.