Welcome to JSR performance.... Your Engine builder.

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John Stallworth, formally the head builder for Nmotion ATV has taken his craft to a new level. Building the biggest baddest engines on the planet. John has been building Engines for Racers for many Years and now has opened his own shop. Under JSR preformance John is able to push the limit on engine combinations and cylinder sizes. JSR works directly with the foundries to build the best cast aluminum replacement cylinders available. Give us a call for your next build. When you get it to the track you will be glad you did.