86 ATC 250R UPGRADE
86 ATC 250R SERIES

It may sound odd for Duncan Racing to perform a Paul Turner Racing engine upgrade. All of the stock hardware was freshly cadmium-plated. Before the building started, the cases and cylinder were stripped, sand-blasted and powder-coated. It was blown completely apart for a complete rebuild that included a new piston, rod, bearings, seals and more. While the chassis was on its journey, the ATC’s liquid-cooled two-stroke engine was on its own mission. The ATC almost looks like a restoration but packs a national-level race engine. Three-wheelers are also a little easier to get some jump style on than a modern quad. All of the powder coating was handled by Powder 1 in El Cajon, California.

The stock shifter, kickstarter, footpegs and rear brake pedal were all powder-coated before being remounted on the chassis or engine. The front and rear fenders are also Maier OEM-style plastic, and so is the front headlight cover over the original headlight. Maier OEM replacement tank scoops were added to the tank. That process started with a stock capacity, stock color Clarke Manufacturing plastic tank. Part of that immaculate appearance is thanks to an OEM-replica sticker kit, but mostly because all of the body parts were replaced. The ATC is so bright and smooth that you would think it was fully refinished. All of the stock skid plates were refreshed and mounted. A Renthal ATC-bend handlebar was fitted with ODI grips, a refurbished stock thumb throttle and a Works Connection clutch perch. The replica stock plastic is from Maier.Īt the front of the machine, Duncan remounted the stock radiator. Everything on the machine is either rebuilt or replaced. From the front, the Duncan ATC looks mostly stock. While they were fitting up the back of the bike, a stock airbox was mounted up, but it was filled with a K&N filter element with an Outerwear cover. We tested the fully rebuilt ATC at Dumont Dunes, so the fabulous stock wheels were replaced with DWT wheels and Skat Trak dune tires for more fun in the sand. A Carlisle 23-inch front and 20-inch Tech4 rear tires were mounted up. Stock rims were powder-coated to look like the stock anodized aluminum rims. The rear also needed a Sunstar sprocket and an RK 520 O-Ring chain.

86 ATC 250R SERIES

The brakes are stock as well, but they use EBC pads and Duncan Racing Crown Series brake lines. A stock rear shock was fully rebuilt and refinished before the parts were added.Īgain, powder-coated, rebuilt standard hubs are used in the rear. Instead of other stock parts, the swingarm was finished up with an RPM 49-inch Dominator axle, bearing carrier and anti-fade nut. Duncan believes the ’86 parts are “superior in function to the ’85 model.” A stock 1986 swingarm was rebuilt and refinished.

86 ATC 250R UPGRADE

The stock ’85 swingarm was in decent condition, but Duncan chose to upgrade the swingarm, rear bearing carrier, axle and rear brake caliper to 1986 ATC parts or specifications. The front hub was also rebuilt and powder-coated. All of the hardware is re-plated, powder-coated or replaced. A stock ATC 250R fork was rebuilt and mounted to the frame. Slowly and carefully the ATC was rebuilt starting with the refurbished frame. Only then was it powder-coated Bengal Red. It did need to be stripped, sand-blasted and inspected for cracks. The frame required no real rebuilding, welding or gusseting. This machine was apparently in good condition. When the vintage ATC arrived at Duncan Racing, it was pulled completely apart with no nut or bolt left fastened.

86 atc 250r