Honda Hrc Xr628
HONDA HRC XR628
CW TEST
Mild to Wild via a Factory Hop-Up Kit
CHANGE HASN’T COME QUICKLY TO HONDA’S XR600. Created in 1985 by increasing the XR500’s bore and stroke, the 600 has survived year after year with minor updates. It’s always been a pleasant, reliable dirtbike, and modified versions have done well in competition, especially in Baja off-road races, but the question has remained: When is Honda going to get serious with the XR?
A delayed introduction of the 1991 XR600 heightened expectations of an all-new bike. Dreams of a powerful, lightweight killer-XR —perhaps with an oval-piston engine-danced in the heads of four-stroke freaks. But Honda threw us a curve ball. The '9 1 isn’t all-new. though it is significantly updated, with a new silencer to improve its mid-range power, a cartridge fork, larger-diameter rear shock, disc rear brake and a shorter swingarm. But there still is room for excitement, because an optional Honda Racing Corporation 628cc hop-up kit is available for guys looking fora bit more thump from their Thumper.
The $1000 HRC kit includes a bigger-bore cylinder (100mm versus the Stocker's 87mm). a piston kit. new camshaft, clutch basket and primary-drive gears, gaskets and installation instructions.
A different exhaust silencer is also needed to get full benefit from this kit, but it's not included in the package. Rather, Honda makes recommendations on silencers that are compatible but have to be purchased separately. Our XR628 test bike was fitted with a stainless-steel Supertrapp unit that will sell in the $150-$175 range. And then there's the installation of the kit: Honda’s fiat-rate labor manual lists the labor for replacing the top-end at 2.2 hours; changing the primary gears shouldn't add more than an additional hour. So, unless you do the work yourself. figure on $150 for labor. The total price of the kit, pipe and labor, then, comes to about $1300. Adding that figure to a stock '91 XR600R’s list price of $3698 bumps the price of the HRC XR628 to $5000. some $350 more than a 1991 Husky 610 WXE and $200 more than a new KTM 600, but $500 less than a kick-start ATK 604 or a Husaberg 501.
Honda saved us the trouble of getting the kit installed by shipping a fully assembled 628 from their factory in Japan. We also borrowed a stock 1991 XR600 for comparison purposes.
With the exception of the exhaust silencer, the 600 and 628 look identical from the outside. Kickstarting each bike hints at the differences between the engines: The 628 requires a healthier prod to force its higher-compression piston through its stroke. Once started, both engines run smoothly, and the 628 idles just as well as the 600, though more loudly.
But that’s where the similarity in engine characteristics ends. The 628 makes substantially more power than the stocker (a 25 percent difference, according to Honda). The regulation 600 produces only fair power at lower engine revolutions, with nice, but not awesome power in its midrange and on top. The 628 barks into a strong surge right off idle and continues building great power that doesn’t end until the engine is screaming like a ported 80cc two-stroke. The powerband is extremely linear, with absolutely no hesitation or flat spots at any throttle setting. There’s always enough power available to lighten the front wheel through whoops and overjumps, and the engine is very responsive while being extremely controllable and non-intimidating.
Indeed, Honda’s claimed power increase with the HRC kit actually seems understated. The 628 will blur the rider’s eyes in an uphill sandwash —in fact, we never encountered a situation where the engine showed even the slightest hint of bogging. The HRC XR humiliates the stocker in drag racing and roll-ons, and with a top speed in the high 90s, the 628 smokes the 80-mph 600 on fast dirt roads.
An off-road motorcycle with the power and speed of the HRC XR628 demands good suspension and brakes. And it has them. The ’9 1 XR600’s new fork and shock perform very well on all kinds of off-road terrain, regardless of the rider’s ability. Both ends are responsive to small bumps, yet get progressively stiffer to avoid bottoming on hard hits. The suspension’s soft initial movement, combined with a wide, plush seat, makes an all-dav ride on the XR a comfortable proposition.
When pushing the 628 to desert-racing speeds across rough, whooped ground, the bike’s ride remains comfortable, but gets very busy. With a full-tank weight of nearly 300 pounds, the XR forces its suspension to work hard to keep the machine tracking straight, and the shortened swingarm contributes not only to the rear-end's willingness to come around hard when power is whacked on. but also to the bike’s rear-wheel wag. This hyper-action can b felt by the rider and at first causes some concern, but the XR never does anything wrong; it just lets the rider know that slightly slower speeds would be preferable.
A heavyish four-stroke Single like an XR628 would seem a poor choice for a woods rider, but National Cross Country Champion Scott Summers proved that theory wrong by winning several events overall during 1990. Of course, not every rider is capable of wrestling a 300-pound bike down tight trails, even though the XR628 is surprisingly adept in tight going. Its short swingarm. light steering and great low-end torque help disguise the Honda’s bulk at trail speeds. But picking the bike up after a fall, or trying to lift it over a log. will remind the rider that the XR is a mighty big machine that's more at home in the desert than the woods.
Used as a desert bike, the HRC XR628 is a neat motorcycle. It’s also a great long-distance trail bike, and a skilled racer can be competitive on the 628. The HRC-kitted bike also is a good choice for guys who ride on jeep roads or in the wilds of Baja, where comfort and reliability are mandatory, and power and speed add to the fun level.
Or you can make up your own reason to justify buying a new XR600R and the HRC 628 kit. It may not be the dream XR many of us have lusted for. but it’ll definitely do until that bike comes along. E3
HONDA HRC XR628
American Honda Motor Corp.
