Building The Baja Beast: Johnny Campbell's XR650R 3.26.2002

Building The Baja Beast: Johnny Campbell's XR650R 3.26.2002

When it comes to preparing the XR650R for what many feel is its mission in life: winning high-speed desert races, Johnny Campbell has some tricks up his sleeve. As good as it is off the showroom floor, a few strategic tweaks make it capable of winning a race as brutal as the Baja 1000.

Nobody knows more about getting the XR650R race-ready than five-time Baja 1000/2000 Champion Johnny Campbell. The first order of business is modifying the suspension. Stock suspension is ideal for trail riders, but for Campbell and company, serious speed calls for a corresponding change in suspension.

"Suspension tuning is really important for different applications—different courses, different terrain," Campbell points out, "so we're constantly trying to improve that and make it work even better. That's probably the most critical area."

Working in conjunction with Precision Concepts, Campbell replaces the standard springs with stiffer ones: 0.44 kg/mm fork springs and a 9.7 kg/mm shock spring taking the place of the 0.43 and 9.5-rated stock components. In addition, valving is revised with less compression damping, less low-speed rebound and more high-speed rebound.

With the biggest, most powerful and most flexible engine in the business, the XR650R doesn't need much in the way of a performance boost. "Being that we have a big powerplant to begin with, it's just making the right type of power out of that power—making it smoother and harder-hitting," Campbell says.

He starts with the HRC Power Up Kit (Honda part number 06130-NLB-010). This kit includes a high-compression 11.5:1 piston (stock is 10.0:1) with rings, wrist pin and circlips; high-performance cam with wider, more durable cam chain and related parts; heavy-duty clutch springs; an assortment of jets; a racing spark plug and a manual/parts list. Mild porting optimizes air/fuel flow, while HRC-spec holes are cut into the airbox cover/left sidepanel.

Tuning the power delivery to the particular course, terrain and even weather is most often a matter of swapping exhaust systems. Campbell prefers a Bassani for terrain that demands linear delivery while he turns to a Pro Circuit for more grunt off the bottom. The additional power enables Campbell to run taller gearing, with the 15/47 sprockets from Renthal allowing an honest 110 mile-per-hour top speed (standard gearing is 14/48). Tying the two sprockets together is the innovative and durable D.I.D. ERV-2 X-ring chain (Honda part number DID520ERV2-120L).

Tires are crucial as well. Desert racers need excellent traction, but tires must also last many miles and resist flats. Thus, a 120/100-18 Dunlop D739 Desert A/T goes onto the rear wheel filled with a Dunlop heavy-duty tube inflated to 16 pounds per square inch. Front tire choice varies. It can be the 90/90-21 Dunlop D606 (a DOT-legal dual-sport tire) with Dunlop heavy-duty tube at 16 PSI for hard-packed terrain or the 80/100-21 D752 with a Dunlop mousse (solid foam rubber tube substitute) for sandy conditions.

To increase range, a 3.2-gallon IMS tank replaces the stocker. It's equipped with a dry break or quick-fuel adapter for rapid pit stops. IMS also manufactures the wider footpegs, though Campbell avoids the lightweight titanium versions which, he feels, are more susceptible to breaking in heavy contact with rocks or other unfriendly objects.

Campbell performs a number of other seemingly smaller modifications that add up to big performance benefits. Braking's oversized "wave" front rotor provides increased braking power and feel and is tougher as well. Ditto for the heavily finned and oversized works rear brake caliper. Answer's proven, ultra-strong ProTaper Doug Henry-bend aluminum handlebar replaces the stock part. The extra girth requires a BRP top triple-clamp. A Scotts steering damper helps stabilize the steering, especially at high speeds—a must-have for desert racing.

In addition, there are many other things like an on-the-fly clutch adjuster, Acerbis plastic hand guards and hand-picking seat foam that's just right. "It all adds up, because every little bit counts at the end of a thousand-mile race," Campbell grins. To make sure the package is perfect, Campbell tears the finished bike down to the last screw and reassembles it to Team Honda specs. But when he—or Precision Concepts, which is now responsible for building the team bikes—is done, Campbell knows the bike is the absolute best an XR650R can be. In other words, it's the weapon that a five-time Baja 1000/2000 champion trusts chase win number six.

Of course they leave a lot out.

Bell did a lot of detail work inside the front suspension including a lot of polishing.
The race bikes used a highly modified CR500 rear shock but that is only an advantage at 1X race speeds and would slow us mortals down.
The also used a Ti rear spring. JC has broken one of his wrists twice and likes a relatively cush setup.
The Team bikes never used the HRC piston as the bike had too much power for long distance races and it tended to come out from under JC. They did play with a milled HRC piston a few times and that worked some high altitude stuff plus allowed Pemex in emergencies.
There's a lot more too like a mod inside the airbox and routing the carb vent hoses over the carb and back into the airbox and so forth.
None of this stuff was Campbell's work in reality. Most of it came out of Ogilvie's association with Precision Concepts when PC was running the B bike and JC was on the A bike. The B bike was faster and soon PC was running the A bike. The guy who did the porting is one of Bob's long-time friends. Some of the work on the airbox came through Jonah Street and an aerospace friend of his at Boeing.
The best stories are from when Bell was running the B bike IMHO.

AURORA wrote:Building The Baja Beast: Johnny Campbell's XR650R 3.26.2002

When it comes to preparing the XR650R for what many feel is its mission in life: winning high-speed desert races, Johnny Campbell has some tricks up his sleeve. As good as it is off the showroom floor, a few strategic tweaks make it capable of winning a race as brutal as the Baja 1000.

Nobody knows more about getting the XR650R race-ready than five-time Baja 1000/2000 Champion Johnny Campbell. The first order of business is modifying the suspension. Stock suspension is ideal for trail riders, but for Campbell and company, serious speed calls for a corresponding change in suspension.

"Suspension tuning is really important for different applications—different courses, different terrain," Campbell points out, "so we're constantly trying to improve that and make it work even better. That's probably the most critical area."

Working in conjunction with Precision Concepts, Campbell replaces the standard springs with stiffer ones: 0.44 kg/mm fork springs and a 9.7 kg/mm shock spring taking the place of the 0.43 and 9.5-rated stock components. In addition, valving is revised with less compression damping, less low-speed rebound and more high-speed rebound.

With the biggest, most powerful and most flexible engine in the business, the XR650R doesn't need much in the way of a performance boost. "Being that we have a big powerplant to begin with, it's just making the right type of power out of that power—making it smoother and harder-hitting," Campbell says.

He starts with the HRC Power Up Kit (Honda part number 06130-NLB-010). This kit includes a high-compression 11.5:1 piston (stock is 10.0:1) with rings, wrist pin and circlips; high-performance cam with wider, more durable cam chain and related parts; heavy-duty clutch springs; an assortment of jets; a racing spark plug and a manual/parts list. Mild porting optimizes air/fuel flow, while HRC-spec holes are cut into the airbox cover/left sidepanel.

Tuning the power delivery to the particular course, terrain and even weather is most often a matter of swapping exhaust systems. Campbell prefers a Bassani for terrain that demands linear delivery while he turns to a Pro Circuit for more grunt off the bottom. The additional power enables Campbell to run taller gearing, with the 15/47 sprockets from Renthal allowing an honest 110 mile-per-hour top speed (standard gearing is 14/48). Tying the two sprockets together is the innovative and durable D.I.D. ERV-2 X-ring chain (Honda part number DID520ERV2-120L).

Tires are crucial as well. Desert racers need excellent traction, but tires must also last many miles and resist flats. Thus, a 120/100-18 Dunlop D739 Desert A/T goes onto the rear wheel filled with a Dunlop heavy-duty tube inflated to 16 pounds per square inch. Front tire choice varies. It can be the 90/90-21 Dunlop D606 (a DOT-legal dual-sport tire) with Dunlop heavy-duty tube at 16 PSI for hard-packed terrain or the 80/100-21 D752 with a Dunlop mousse (solid foam rubber tube substitute) for sandy conditions.

To increase range, a 3.2-gallon IMS tank replaces the stocker. It's equipped with a dry break or quick-fuel adapter for rapid pit stops. IMS also manufactures the wider footpegs, though Campbell avoids the lightweight titanium versions which, he feels, are more susceptible to breaking in heavy contact with rocks or other unfriendly objects.

Campbell performs a number of other seemingly smaller modifications that add up to big performance benefits. Braking's oversized "wave" front rotor provides increased braking power and feel and is tougher as well. Ditto for the heavily finned and oversized works rear brake caliper. Answer's proven, ultra-strong ProTaper Doug Henry-bend aluminum handlebar replaces the stock part. The extra girth requires a BRP top triple-clamp. A Scotts steering damper helps stabilize the steering, especially at high speeds—a must-have for desert racing.

In addition, there are many other things like an on-the-fly clutch adjuster, Acerbis plastic hand guards and hand-picking seat foam that's just right. "It all adds up, because every little bit counts at the end of a thousand-mile race," Campbell grins. To make sure the package is perfect, Campbell tears the finished bike down to the last screw and reassembles it to Team Honda specs. But when he—or Precision Concepts, which is now responsible for building the team bikes—is done, Campbell knows the bike is the absolute best an XR650R can be. In other words, it's the weapon that a five-time Baja 1000/2000 champion trusts chase win number six.

I remember reading in Dirt Rider about the airbox mod. They said team Honda had built what they called the "Bat Wing" which was a rounded piece of aluminum inside the airbox that would help smooth out the air intake into the carb. For quite a while, I believe SRC sold the 'Bat Wing' air intake, but they're no longer in business.