Baja Buster

Baja Buster

Chunking knobs on Honda’s XR650 desert racer

WHY WOULD ANYONE WANT AN XR650 WITH even more power? After all, in stock form, the hulking alloy-framed Thumper shreds with wild abandon.

Maybe to win off-road races? Good answer, as the breathed-on, Baja 500-winning XR650R of Team Honda’s Jonah Street and Steve Hengeveld proved. Cycle World rode the bike a week after its Mexico victory.

The motor in the racer is currently the development bed for a soon-to-be-released HRC Power-Up kit. The displacement doesn’t change, sticking at 649cc, but compression is bumped from 10:1 to 11.5:1. Next ingredient is a hotter cam that opens sooner, closes later and lifts the valves a bit farther. Also included in the kit are wider cam sprockets utilizing a stronger chain, looked after by a stiffer tensioner spring. With the power increase also come beefed-up clutch springs. The exhaust is built by XR’s Only to a spec provided by Honda Japan. Of course, more air is needed, hence the cutaway airbox cover and richer carb jetting.

On the chassis side, mods are less intensive than with the old XR600 racers. The frame is completely stock, with most of the attention paid to suspension settings for the wideopen pace desert racing requires. Precision Concepts of San Diego valves the suspension and, depending on the course, runs slightly stiffer springs front and rear. For more capacity and quick fuel stops, a dry-break IMS tank holds 3.2 gallons of VP C-12 race gas. IMS also supplies beefier footpegs.

The handlebar is a Pro-Taper Honda CR Hi bend with a BRP top triple-clamp that moves the bar clamps slightly forward. A Scott’s steering stabilizer is used with a Precision Concepts mounting kit. Brakes get an upgrade via an XR650L caliper bracket and 256mm Braking rotor.

This year, the Honda team is using Dunlop tires, a special 902 front and a 739 AT rear with heavy tubes. Final gearing is 14/45, good for a radar-gunned top speed of 107 mph in the high deserts of Nevada.

We’re pretty big XR650 fans-provided 99 percent of the riding is above 15 mph. Out of the slow stuff, big power offsets big weight. Now, add a good 20 percent more pizzazz, and you get an idea of what this muscled-up racebike feels like. It’s still very rideable from just above idle; in fact, it’s only a bit cammy just as you crack the throttle. You could almost trailride this bike-almost. But if the terrain opens up, for instance a deep, horsepower-robbing sandwash, then the XR has just what you need to rip right up to speed. And on a good fireroad, there isn’t a better bike. As you roll it on, you get great four-stroke hook-up, and spinning the rear is just a touch more throttle twist away. Can you say “dial-a-slide?”

The PC-tweaked suspension is a necessary complement to the boosted motor-you tend to hit stuff harder and faster. It’s a bit stiff initially to stop the bike from wallowing and allow riders to pound into things, with bottoming much more progressive than stock. Plus, rebound is better-controlled. All around, a much more aggressive-handling package that may not be as comfy as the stocker, but you can sure haul ass on it.

The amenities allow you to move around a bit easier, too, especially the forward-position handlebar. The gas tank is slimmer than the stocker, and the IMS footpegs grippier, necessary when you’re hanging on, literally, by the soles of your boots at times. About the only thing to remember is to bring your earplugs, as the open-meg exhaust will leave you deaf in little or no time. Oh yeah, and a lot of tires. Knobs have a way of disappearing rather quickly. -Jimmy Lewis