The discussion on sprocket selection should also include a few points about chain. The prevailing rule is that the chain and sprockets should be changed at the same time.  While on the surface it is difficult to disagree with this concept, the inevitable conclusion is that the chain and sprockets are left together until they all just wear out.

One also might consider that the people who made this 'rule' are the same people who sell the sprockets and chain.

We should consider what happens when a chain drive system is put under hard use in a hostile environment. In the context of an off-road bike, there is ample opportunity for grit to make its way into the drive system and cause wear. The most destructive event, though, is chain stretch. The process is that the link side plates elongate which causes the distance between the link pins to increase. The sprockets have no choice but to wear to meet the ever increasing distance between the link rollers.

Since we can't keep the chain from stretching, we can protect the sprockets to a large degree. This destructive process can be interrupted by replacing the chain each season. Replacing the chain will force the wear back to the dimension of a new chain and prolong the life of the relatively more expensive sprockets. The chain should, of course, continue to have regular maintenance and effective lubrication.

The next thing item is to choose among an o-ring chain, a heavy duty (HD) chain, or the standard chain.

Maybe it is just my Midwestern upbringing, but it seems to me that the o-ring chain is too costly for what we ask of it. The stronger side plates are nice but the Internal wear issue is not as important since it will only be in use for one season. The least expensive standard chain seems to be a potentially costly choice if it stretches too quickly and too far in a season. The HD chain seems just right because it is a relatively low cost choice with the added feature of stronger link plates keeping stretch to a minimum over the course of the one season.

The only consideration with the Heavy Duty chain on the RL250 is the spacing of the countershaft sprocket from the engine case. It is possible that the additional width of the 428HD chain will cause contact with the engine case when using a sprocket less than 14 teeth. This condition is easily rectified by spacing the sprocket out from the engine using two new lock washers that are normally used to lock the sprocket retention nut to the shaft.

Matrix has 428HD chain in stock and the hardware required to safely and cleanly replace the sprockets. The Matrix Roller Chain Tensioner Modification Kit works very well with the 428HD chain.

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Last modified: 05/26/14