BJ's ATV Rentals, Parts, Accessories & Repairs, Inc., is a large shop in the town of Grover Beach, founded and owned by John "BJ" Aitkens and Evelyn Valentino. Besides renting ATV's for dune riding on the Oceano Dunes, we carry everything you might need for a good day riding in the sand, including ATV and dirt bike parts and accessories - both dealer and aftermarket.. Full line of ATV 4 Wheelers - From children to adults - Full service & repair on ATV's & Motorcycles - Parts & Accessories - Safest ATV Riding Record - Knowledgeable instructors