I switched the top gear on my â€™98 ZRT 600 to one tooth smaller, but now the chain is real loose! I canâ€™t believe the chain should be as loose as it is, nor can I believe it stretched that far. This is with the adjuster turned all the way in. What am I missing? And, do I gain much by decreasing the top gear size like my local shop said?
Each gearing combination (top gear size and bottom gear size) requires a specific length (# of links) chain. By going to a smaller top gear, you most likely now require a shorter (link) chain. Normally you can find a chart for each year of machine from a particular manufacturer so you can see what the proper combination is for a specific chaincase length.
Will you gain much with the smaller top gear? Potentially. It all depends on how much power youâ€™re making and the load being presented. The stock gearing is selected to prevent over-revving, so it is good for a long run on a very cold day with minimal drag at sea-level (usually). If you donâ€™t hold it open for very long, donâ€™t ride at very cold temps, and donâ€™t ride at sea level, then you could very well experienced much snappier operation and acceleration, but potentially less top speed. The key is that you donâ€™t go into an over-rev condition, because this is what will happen if your gearing is too low, so know your proper operating RPM and watch the tach when it gets really cold out and youâ€™re winding it out. It is more of a trail and error situation than it is â€œdo thisâ€ for your particular sled. Many times when a deep lug track is installed or the snow is wet and heavy you will experience better belt life with a slightly lower gear ratio. Most anytime you go up in elevation you can benefit from lower gearing, but it all depends on so many factors that we just canâ€™t make blanket recommendations.