Factory Amateur MX Bikes—Preston Kilroy’s Suzuki RM-Z250

Suzuki 250F at the Loretta Lynn’s Amateur National Motocross Championship.

Preston Kilroy’s Suzuki RM-Z250 factory racebike.
BarX/Chaparral/Fly/Suzuki Factory Racing’s Preston Kilroy races a fairly stock RM-Z250 with a few aftermarket items.Shan Moore

Every year, top amateur motocross racers from all around the country gather in Hurricane Mills, Tennessee, for the Loretta Lynn’s Rocky Mountain ATV/MC AMA Amateur National Motocross Championship. This year’s event took place on July 28 to August 3, and we searched the pits to find some of the trickest racebikes in the amateur paddock.

We visited the BarX/Chaparral/Fly/Suzuki Factory Racing rig and got a chance to look at Preston Kilroy's Suzuki RM-Z250. The Afton, Wyoming, resident finished the week with second overall in the 250B Limited class with 2-1-2 moto scores and third overall in the Schoolboy 2 (12-17) B/C class with 2-3-8 race finishes. Between Kilroy's motos, his mechanic Kade O'Grady spoke with us about his setup.

“First of all, Preston likes a pretty neutral, even feel on the bike,” O’Grady explained. “He’s pretty easy. He likes his bars and clamps really tight so it doesn’t move around a whole lot on him. He likes everything pretty neutral.”

Preston Kilroy’s Suzuki RM-Z250 factory racebike stock triple clamps.
The triple clamps are stock, while the Showa A-Kit suspension components are set up by RG3.Shan Moore

Starting at the front, Kilroy runs a Mika Metals handlebar and grips, a Works Connection clutch perch and lever, and a stock front brake lever. The triple clamps are also stock, while the suspension components are Showa A-Kit.

“The Showa A-Kit suspension is set up by RG3,” O’Grady said. “He likes the suspension to be fairly soft and pretty plush. He just likes it to absorb the bumps so he can charge into stuff really hard and not have to worry about it deflecting or doing anything weird like that.”

Preston Kilroy’s Suzuki RM-Z250 Galfer rotors and braking components.
The Galfer rotors are standard size; the rest of the braking components are OEM.Shan Moore

The wheels are stock with Pirelli MX32 tires. Aside from the Galfer rotors that are the standard size front and rear, the rest of the braking components are OEM. The team uses MotoSeat seat covers and Acerbis plastics. The skid plate is made by Acerbis as well, but is slightly modified to keep dirt from getting everywhere.

“There’s a little mud flap up that comes right up to the exhaust to keep the front of our engine cases and radiator hoses clean, and so we’re not getting dirt packed up in there all the time,” O’Grady mentioned.

Preston Kilroy’s Suzuki RM-Z250 factory racebike engine.
Twisted Development handles the engine work on Kilroy’s RM-Z250 racebike.Shan Moore

The engine work is done by Twisted Development, and the team runs complete Hinson Racing clutch assemblies and ignition covers. The stock header pipe is paired with an FMF Factory 4.1 RCT slip-on muffler. Other aftermarket items include Mika Metals sprockets, a ProX chain, and a DT1 air filter. O’Grady also spoke a bit about Kilroy’s riding style.

“He’s super, super smooth and really thinks about his line choices and stuff, so he’s never really wearing anything out,” O’Grady said. “His levers and handlebar have to be perfect. Just the cockpit has to be perfect, but besides that he’ll pretty much ride anything as long as it’s set up how he likes it.”