2016 Suzuki RM85 Factory R&D Project Bike

Improving Suzuki's Smallest Race Bike

From the August 2016 issue of Dirt Rider Magazine

My son Jack and I got to take home the RM85 from Dirt Rider’s 2016 85cc MX Shootout (June) for long-term testing. When I was a 13-year-old kid a magazine photo of Buddy Antunez on his R&D 80 was the highlight of my treasured wall of posters, and Jack really liked the RM85, so we were both happy.

The long-term testing quickly morphed into a project bike build, one that would keep an eye on the old wallet. My first step was to contact Dean at R&D Racing. Dean was gung-ho to dig out the RM’s potential without going overboard on the budget. When I dropped off the bike, I noticed that on the wall hung a 2-foot by 3-foot photo of Antunez on the bike of my childhood dreams.

2016 Suzuki RM85 Factory R&D Project Bike
Jack CarriggPhoto by Drew Ruiz

A few days later I got a call from Dean, “You know, this bike is really good. It’s putting out some serious power on the dyno. I’ve done a Vortex ignition with custom mapping, I’ve added one of my EVC power-valve covers, a VForce reed cage, and I’m not sure we even need to get inside the motor.” The Exhaust Velocity Control power-valve cover slows the rate that the power valve opens to help with engine torque. He went on to explain that with his map, VP’s MRX02 fuel, and a little tuning, he had gained 2 hp in the mid and it was signing off higher, with more than 24 hp.

2016 Suzuki RM85 Factory R&D Project Bike
The Vortex ignition has an on-the-fly map switch, but Dean sets one map to be ideal at sea level and the second for the higher elevation at Mammoth.Photo by Drew Ruiz
2016 Suzuki RM85 Factory R&D Project Bike
The R&D power-valve cover uses two additional springs to slow down the timing of the engine’s stock power valve to avoid a dip in the power.Photo by Drew Ruiz

The bike had been crashed pretty good at the shootout. It needed a new radiator and wanted a cosmetic upgrade. Suzuki provided the radiator, and I added a Works Connection brace. DeCal Works created the clean-looking graphics and provided the seat cover, and its new venture, MXPlastic.com, provided the replacement plastic.

On Jack’s first few rides with the modded motor and the two-teeth-larger Renthal rear sprocket, his biggest impression wasn’t necessarily the horsepower increase but how quickly the motor went through the available power and led to the next gear. “I just kept shifting that thing and it just kept eating.” The engine pulled hard out of the corners leading up the steep hills of Glen Helen, which made for easy passing opportunities.

2016 Suzuki RM85 Factory R&D Project Bike
The DeCal Works graphics are partly retro and partly just clean looking—perfect to appeal to both dads and kids.Photo by Drew Ruiz

The stock suspension’s balance was good, but overall it was a bit harsh. Other shootout testers had mentioned that the fork would bounce off of some bumps. R&D revalved both ends; our best settings had the sag at 105mm, fork height at 10mm above the top clamp, and an aftermarket rear linkage that I scavenged from a used RM85 (I believe it is a PR2 or R&D unit) that was designed to soften up the rear end. One of the coolest mods is that R&D shaved down the rear shock’s coil to get a softer rate without replacing the stock spring.

2016 Suzuki RM85 Factory R&D Project Bike
R&D shaves the stock shock spring to get the lighter rate they want with the stock spring. It looks super trick and is actually a cheaper option than a new spring.Photo by Drew Ruiz

These settings complemented the bike’s already good handling, making it easy to manipulate on the rough afternoon track. The RM85 is easy to turn in, and its strong low-end power makes it extremely nimble in the corners. “I could focus on my technique instead of figuring out the way the bike handles,” Jack explained. “It also feels really light when turning in.”

Jack felt the stock RM85’s brakes were, “just okay,” so we upgraded them with Galfer wave rotors and steel-braided brake lines. The result? “They stop really fast. The feel is much more touchy though, so you have to be careful!”

2016 Suzuki RM85 Factory R&D Project Bike
Jack CarriggPhoto by Drew Ruiz

The handlebar bend was too narrow and with too much sweep. The remedy was the Renthal 7/8-inch 971 bend bar with Renthal full-waffle grips. We cut them narrower by a half inch at each end to help Jack feel comfortable, and the new bend helped with lessening and controlling headshake and, “The stock bars made my elbows tuck in, making it seem hard to turn.”

The gearing on the bike was a bit long (as are most of the stock 85s). Jack doesn’t like riding a clutch hard; he prefers to use throttle control. We picked Renthal for its light weight and good looks. We added a one-tooth-bigger Renthal sprocket. That was good, but we settled on better with a 49 (plus two over stock). “It really helped me turn the bike; rolling on the throttle was perfect compared to clutching all the way through the corner.”

2016 Suzuki RM85 Factory R&D Project Bike
Jack CarriggPhoto by Drew Ruiz

Making use of the newfound horsepower and braking power, we replaced the factory tires with Dunlop’s MX3S. “They really help the bike hook up, not just the rear, so the front no longer pushed up or out of ruts.”

Like most mini dads, I’m confronted with the overwhelming price to keep my kid on the track and racing. A brand-new Suzuki RM85 is very affordable, and by just bolting on a small number of tuning components and getting a suspension revalve we ended up with a National-worthy workingman’s racebike.

2016 Suzuki RM85 Factory R&D Project Bike
Jack CarriggPhoto by Drew Ruiz