In the previous two episodes of our Honda CBR600RR
project bike saga we renovated it from a crashed street bike into a dedicated road racer. We then suited up and hit the track, trading paint with the WERA Motorcycle Racing Club at Southern California’s Auto Club Speedway. The weekend proved the worthiness of Big Red’s Supersport in mildly modified form in the 600cc class. It also showcased the importance of select aftermarket racing goodies not to mention the aptitude of Jett Tuning
in regards to race bike assembly and set-up. For the final installment, we traveled to Las Vegas to compete at the double header WERA West series finale.
After a successful race weekend, one in which the motorcycle returns to the garage shiny side up, Jett performs a bit of preventative maintenance to ensure that it’s ready for the next outing. Since our machine is in a more production-based state of tune, upkeep was limited to siphoning the remaining few quarts of VP race gas and replacing it with pump fuel. Racing fuel is usually more volatile than standard 91-octane gasoline and can breakdown quickly when exposed to air and gum up parts of the fuel system.
The brakes hydraulics also received attention and the used fluid was purged for some fresh Pro Honda Oils brake fluid to ensure there won’t be any mushy feel the next time we squeeze the lever. If you rely heavily on the rear brake then it’s a good idea to flush it too. Since the engine only had a few hundred track miles we skipped the oil change and scheduled it after the third weekend of runtime.
) Body position, quick clutch work and launching the bike at the right RPM are critical in trying to get a good start at the beginning of a race. (Center
) The stock clutch components work great and make the CBR easier to launch helping the rider get out front early in the race. (Below
) Pirelli’s Diablo Supercorsa racing tires are the finest DOT-labeled road racing tires money can buy. The product range in terms of fitment in compounds is equally superior.
During the cleaning process Jett noticed oil leaking from the shock’s main seal so it was removed and returned to JRi Shocks
North Carolina headquarters for service. Since the component was under warranty, repairs were completed free of charge and JRI had it back in our hands quickly so we wouldn’t miss the next race.
Situated near the outskirts of town next to Nellis Air Force Base is Las Vegas Motor Speedway. The motorsport complex hosts a number of tracks including the 1.75-mile “outside” road course located adjacent to the looming Superspeedway oval that NASCAR runs on each spring. For motorcycles the track uses a nine-turn clockwise configuration. The pavement is smooth, bump free and the grip is pretty good too, especially in the afternoon once the desert’s fine layer of dust and sand has been erased by streaks of tire rubber and the asphalt soaks in some sunrays.
Typically WERA events are one-day only affairs with races held on Sunday. But since this was a double header weekend, races would be held on Saturday too. To give riders extra preparation, Racer’s Edge Performance hosts a trackday ($185) prior to the races giving riders added seat time to practice and set-up their machines.
Having never ridden this track it was crucial to get as much practice as possible. Because the circuit is short, flat and devoid of any blind rises or turns it’s fairly easy to figure out the layout and general direction. However, since the course is compact, considerable time is spent on the side of the tires making trail braking and dialing in a fist-full of throttle while your knee puck slides across the asphalt just a little intimidating. Scratch that really intimidating!
Thankfully Pirelli’s line of Diablo Supercorsa racing tires is up to task (see Pirelli
sidebar). During practice and for many of the races we used an SC2-compound front (120/70-17) paired with a 180/60-17 SC2 compound rear. The reason we chose a 180-series tire as opposed to a 190 or 200 section is both a matter of preference and the fact that our production based engine only cranks out around 120 horsepower. While that is a healthy amount for a stock engine, it isn’t so much to overpower it.
We also sampled an SC1 back hoop for one of the races. Compared to the SC2 the tire offered more flex and side grip. It offers so much traction that it actually made the CBR “stall” slightly in terms of roll speed into and out of corners unless we charged and were assertive with throttle inputs at lean. Some riders, myself included, actually prefer the less agro feel of the SC2. However, if you’re an aggressive rider, one that isn’t afraid of pinning it mid-corner and don’t expect the tire to last for more than two or three six-lap races, than the SC1 is the tire for you, no question—it is bolt on speed.
) At a track like Vegas, handling is a more important attribute than outright engine power. Still the Honda CBR is no slouch even with production engine internals. (Bottom
) Galfer braking hardware increased the stopping performance of the CBR600RR. It is crazy how much of an improvement it was over stock.
Similar to Auto Club Speedway there are a number of hard braking zones so the suspension set-up from our last race was in the ballpark but it did need some fine-tuning. Since considerable load is generated on the front end coming into corners we added a couple turns of spring preload inside the fork. This modified the bike’s stance during braking and reduced excessive chassis pitch when entering turns with a firm two fingers of pressure on the brake lever. It also added stability by reducing the bike’s propensity to endo and kept the rear tire in contact with the ground. We also slowed compression damping on each end.
The Galfer-sourced stopping hardware, including Galfer Front Wave Rotor
s, racing brake pads (G1375 compound) and stainless-steel lines, performed flawlessly offering a tremendous amount of stopping power that was easy to apply and modulate everywhere. This set-up exceeds any other production brake set-up even in the high dollar liter-bike class.
Like before the Traxxion Dynamics
AK-GAS fork offered simple and precise adjustment and didn’t require excessive amount of turns to get the desired effect. While the action was responsive, we didn’t get that same level of road feel as experienced at Fontana making it more difficult to truly trust the front end. Even still it performed without incident with zero push, slides or chatter. Our only complaint was the lack of outright road feel. The shock on the other hand proved to be a little tricky to set-up. Part of the problem is the tight fit between the swingarm and the frame making preload adjustments more time consuming. The range of rebound adjustment was also limited and the damping characteristics weren’t as sensitive to fine-tuning.
From track to track, optimum final drive gearing can change slightly and the move from the NASCAR high-banks of Auto Club to the stop-and-go flow of Vegas necessitated a gearing tweak. The 15/44 combo proved to be a close fit, but since we had a few hundred precious power-making rpm remaining before it was time to drop anchor at the end of straightaways we bolted on a one tooth larger (45) Renthal 520 Ultralight Road Rear Sprocket
. This change better optimized acceleration and allowed us to carry fifth gear through the fastest and most important section of the track, Turn 6, a fast slightly banked right-hander.
Regardless of the season, weather in the desert can be difficult to predict. And since we wished to avoid the fuel boiling issue encountered in the 100-plus degree temps during our last 2012 Honda CBR600RR Project Bike 2
episode we relied on VP Racing Fuels
always excellent U4.4 rocket fuel. Despite lacking the outright acceleration punch of MR12 it’s still plenty potent plus it’s more stable in a wider range of temperatures. The CBR’s throttle response continued to be near perfect due to the time Jett spent on its in-house Dynojet dyno and the motor pumps out a smooth stream of power throughout its 15,300-rpm range. The Dynojet Quick Shifter Expansion Module
continued to pay
dividends by allowing instantaneous full-throttle upshifts. In fact, the only complaint in the powertrain department was the lack of a back-torque limiting clutch resulting in considerable rear wheel hop during braking for Turn 1. Exaggerated throttle blips and smooth clutch lever work certainly helped but never enough to cure the problem.
Aside from occasional rear wheel hop entering certain corners that feature hard braking zones, Honda’s CBR600RR doesn’t possess any other glaring problems. Consider its neutral, undemanding riding position, predicable handling manners, and smooth, punchy and rev-happy nature of its engine and we’re surprised that we don’t see more red bikes on the grid. Sure, it isn’t the newest motorcycle in its class, but it is one of the friendliest and easy to ride we’ve experienced in race trim. That, however, could change once racers learn of Honda’s contingency program in the U.S. (see Honda Racing Contingency sidebar).