1. Transmission Chains
Table 1.9 Motorcycle Chains
40Class
50 Class
60 Class
Chain Number
Inside
Chain Number
Inside
Chain Number
Inside
Width (mm)
Width (mm)
Width (mm)
420 425
6.35 7.95* 7.95*
520 525 530
6.35 7.95 9.53*
630
9.53
428**
* Same inside width as ANSI Standard Roller Chain. ** Roller diameter differs from ANSI Standard Roller Chain.
Motorcycle Chains have the following special features: (1) Strength
Quad-staked riveting on the pin head helps to retain the link plate on the pin. Connecting links are press fit. (Riveted connecting links are also available.) Link plates are thicker (heavy) and the rollers are seamless. (2) Wear life Special coated pins, sintered bushings that are oil impregnated, and seam- less bushings with O-rings are used to extend the wear life of the chain. (3) Resistance to dirt, sand, or mud To prevent debris from getting into tight joints, the bushings are extend- ed beyond the inner link plates, and often O-rings are used to seal the chains. This extension and O-rings prevent abrasive material from getting into the chain. (4) Appearance These chains may have special coloring, plating, (gold or silver), or glossy finish on the plates. Sprockets Special sprockets are used for these chains. Numbers 425 and 530 sprockets have the same tooth shapes as standard types. Selection and Handling (1) Usually the specifications differ for each motorcycle or application, even with the same-sized chains. Do not select the chain just by size of the sprocket; take into account the application. For example, an off-road motorcycle travels through dirt and sand, which will get on the chain. You should avoid the use of oil-impregnated sintered bushings for this application. (2) Failure of Motorcycle Chains may result in injury or death. Care must be exercised when connecting or aligning the chains. (3) Both O-ring chains and oil-impregnated sintered bushing chains wear rapidly if the O-rings fall off or if the oil in the sintered bushings is depleted. If either of these situations occur, the chain must be replaced —even if it has not elongated to the limit.
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