Honda's New Motocrossers
Honda's New Motocrossers
What's in store for '84
Honda's first news for 1984 comes from a 1983 success story. The motocross CR line had a wonderful season. Dealers sold out. So the factory cranked up the production lines early and ordered extra boats, and the bikes you see here will be in the dealerships by late October or early November.
The 60cc motocrosser is the least changed, the 80, 125, 250 and open the most changed.
The 1 25, 250 and 500 share several parts: all have a disc front brake, and front wheel assembly very similar to the one used on last year's XR500R. The master cylinder is mounted on the right side of the bars like the XR, but the unit is only half as large. The drive chain has been moved from the right to the left side on the 250 and open bike and they now share rear hubs and aluminum swing arms with the 125. All three sizes have revised rear suspension damping rates. The change is mainly due to a longer link between the frame and Pro-Link rockers. Remote shock reservoirs on the three have been moved from the left side to the right, and air intake boots from the right to left. The 500 and 250 have a Showa shock, the 125 has a KYB. The 500 and 250 have Showa forks with new spring and damping rates, the 125 uses KYB forks with 43mm stanchion tubes. All have adjustable compression damping.
Other changes common tothe 125, 250 and 500 include rubber mounted handlebars, gas tanks with lower profiles (although each is designed to fit a specific size and thus won’t interchange) so the seat doesn't have to tilt as sharply as its front. Redesigned gas caps with rounded top edges and easy-to-grip outer shapes are safer and more efficient. Aluminum rear brake pedals are tucked behind the frame tubing and exposed steel cables connect the pedal to the backing plate’s arm. Side number plates are reshaped and appear interchangeable between the models except for background color.
Engine Changes
The open bike has an all-new engine. lts bore remains unchanged at 89 mm but the stroke has increased \ 3mm to 79mm. Displacement is now 491 cc. The steel lined aluminum cylinder is substantially taller than before and heavily finned. The head also has lots of tall fins and plastic air scoops to ensure a good supply of air across them. An eight-petal reed is fed by a 38mm Keihin carburetor. A lighter clutch hub and five-speed transmission somehow fit inside the tiny new center cases. An aluminum kick start lever is again used but it has been moved to the right side of the engine. No horsepower figures were available, but it’s probably as potent as it looks.
Disc brakes, new engines and exhaust systems trained to A.T.A.C.
The 80, 1 25 and 250 are equipped with A.T.A.C. (Automatic Torque Amplification Chamber). The device consists of a small box or canister (depending on the engine size and restrictions of various
models), and a butterfly valve that lets exhaust gasses enter during low revs then closes as the revs increase. The butterfly valve is placed between the headpipe and canister/box and mechanically controlled by linkage off the crank end. Engine torque and low-speed power is increased when the valve is open and gasses are entering the chamber, actually changing the volume and shape of the pipe. When it’s closed the exhaust is undisturbed and flows through the pipe normally. Thus, the expansion pipe can be designed for top-end revs and power.
Honda’s works 500s have been using A.T.A.C. most of the year but we haven't seen it on their works 1 25s and
250s. Strangely, the usage on the ’84 production CRs is reversed. The 500 is the only model that doesn’t have it.
The 250 also has an all-new engine. The center cases, crank, cylinder, clutch basket and ignition rotor are lighter and the kick starter has moved from the left to the right side. A close-ratio five-speed transmission is used. Carburetion is by 36mm Keihin and six-petal reed.
For the first time in six years, the CR125’s engine isn’t all-new. The exhaust is new and incorporates the A.T.A.C. system, and the cylinder, clutch and ignition have been lightened.
Honda hasn’t forgotten the junior racers. The CR60 has larger diameter forks with 8 in. of wheel travel. New Pro-Link rates are used and rear wheel travel has been increased to 8.3 in. The lighter engine has more power and torque and the transmission is a six-speed.
The CR80 is radically changed. There’s a new water' cooled engine (with a claimed 21 bhp), new pro-Link arms and rear wheel travel of 10 in. Forks have 33mm stanchions and a whopping 9.4 in. of travel. A new frame features a bolt-on rear section just like the big racers. All this and the bike’s weight has been reduced to 137 1b. dry. B
