939970 Primary chain adjuster kit

Maintaining proper tension on your primary chain is essential for smooth shifting and long component life, and this MCS primary chain adjuster kit makes the job easy. It is designed specifically for 1991 to 2003 XL Sportster models, serving as a direct replacement for OEM 39970-91. Over time, the original adjuster shoe can wear down or the hardware can become fatigued, leading to excessive chain slap and noise. This kit includes the necessary components to refresh your tensioner system, ensuring your Sportster's primary drive remains quiet and efficient. It is a straightforward upgrade that every five-speed Evo Sportster owner should consider during their next primary service.