Dimensions of Motorcycle Chains
The basic specifications for motorcycle chains are the same as that of ordinary roller chains, but with some differences. There are three types, the 40 Class, 50 Class and 60 Class.
The 40 Class specs are as follows: those with a chain number of 420 have an inside width of 6.35 mm. The 40 Class with a 425 chain number have a 7.95 mm inner width. The one with 428 chain numbers have an inner width of 7.95 mm.
The next motorcycle chain size is the 50 Class. Those with a chain number of 520 have an inner width of 6.35 mm. If the chain number is 525, the inner width is 7.95 mm. If the chain number is 530, the inner width is 9.53. The 60 Class has a chain number of 630 with an inner width of 9.53 mm.
To give it additional strength, the motorcycle chains have quad-staked riveting at the pin head. This allows it to keep the link plate right at the pin. The link plates are also heavy and they have seamless rollers. Manufacturers also use special coated pins to extend the life of these chains.
Whatever the motorcycle chain size, the bushings almost always go beyond the inner link plates. These are used (together with 0-rings) to keep dirt from entering the joints. Special types of sprockets are also used for the chains.
Choosing a Motorcycle Chain
Even if you know the right size, you have to consider the type of motorcycle you’re using. Even if motorcycle A and B use the same chain size, their specs may differ. For example, an off-road motorcycle wades through a lot of dirt. This means oil-impregnated sintered bushings are not suitable for it.
Measuring the Chain
The following method should work no matter what the motorcycle chain size is. Begin by loosening the axle lug bolt located at the rear tire. You’ll need to use a crescent wrench to do this. Keep doing it until the tire swings easily at the swingarm.
Set the tire forward as much as possible. Rotate the tire until you see the master link chain. You’ll recognize it due to the extra clip. Use a flathead screwdriver to take off the clip.
Pull it off. Pull the sides of the link from each other. Remove the chain. Use a tape measure to get the length. Now you can buy one that is just right for the motorcycle.
Tips and Warnings
If you are putting in the chains yourself, make sure they are correctly installed. If the O-rings fall off, replace the chain immediately. When buying replacements, remember that they are sold in two inch increments.
If you cannot find a motorcycle chain size that is an exact fit, pick the longer one. You can always take off a link to make it fit.