603mods is a rider-run two-stroke race shop based in Rochester, New Hampshire—serving the Seacoast, Lakes Region, and Southern Maine.

This is a private build shop, not a public storefront. All drop-offs and pickups are by appointment only. For shop security and workflow efficiency, our exact address is shared after scheduling.

We respond in the order messages are received. If your bike’s on the clock—we’re on it.

We typically respond within 24–48 hours. Race weekends may delay replies.