Service

SERVICE

Worry-free winter

Because of parking restrictions here at Purdue University, where I am a freshman, I cannot bring my car onto campus. So I intend to buy a Honda CBR600F2, which I can park on campus. My question is, is it advisable to ride throughout the winter, barring any snowfall? Because of the Honda’s manual choke and small-displacement engine, I am curious as to what effect temperatures below or around freezing would have on the bike. Jim Hauser West Lafayette, Indiana

Regardless of its displacement, a modern motorcycle engine is no more or no less susceptible to cold-weather mechanical problems than any modern automobile engine. The CBR600F2 will start easily, run smoothly and perform normally in sub-freezing, and even sub-zero, weather. It will require a little more warm-up time on really cold mornings, but so does an automobile. And, just as with a car, you must add enough anti-freeze to the CBR ’s liquid-cooling system to prevent freeze-up when the thermometer really takes a dive.

Don’t be spooked by the manual choke, either. The only difference be-

tween manual and automatic chokes is that automatic chokes open or close all by themselves according to the temperature of the engine, whereas manual chokes have to be opened or closed by the rider. Once in the operating position, though, one type is no better than the other in aiding cold-weather starting.

Off the wall

If you’re going to burnish the clutch plates, as described in the November ’92 Service column, why put the bike in second gear and against a wall? Why not use top gear and apply the brakes? Less chance of the motorcycle going anywhere, and less stress on the drive train. Robert Erck

Lombard, Illinois

Well, yes and no. Yes, you can use an even higher gear, including top; but the higher the gear, the less “feel” you have for the amount of clutch slippage you re inducing at any given time. This feedback is very important, for you only want to burnish the glaze off of the plates, not fry them to a cinder. And if done properly, this burnishing procedure results in negligible drivetrain stress, no matter what gear is used.

As far as whether applying the brakes is a better technique than butting the front wheel against a wall, consider a few key points. For one, to best assure that the bike won’t move forward, you usually need to apply both front and rear brakes-meaning that you ’ll only be able to put one foot on the ground while slipping the clutch. If anything causes you to lose your balance and put your right foot down—thereby releasing the rear brake-the bike could lunge forward. And if you attempt this procedure with the bike on its centerstand-if it even has one—you won't be able to use the front brake to help prevent rear-tire rotation; more important, you ’ll also lose all of the feedback that is so important to burnishing the plates just the right amount.

Your concerns are understandable, but if the bike is butted against an immovable wall, where-and how far-can it possibly go?

Hold your horses

As you are well aware, motorcycle manufacturers have agreed to a voluntary 100-horsepower limit on the bikes they sell in many parts of Europe. For those of us who live here in Germany, home of the famed autobahn, this power limit is especially frustrating. So, my question is, how can European riders tweak their bikes to U.S. specifications? In particular, I’m interested in the upgrading modifications for Honda’s CBR900RR (called “Fire Blade” in Germany) and VFR750F, and for the European version of Kawasaki’s awesome ZX-11. I’ve attempted to contact American distributors for advice, but have received no reply. Seth Balsam

Stuttgart, Germany

Engine data about European-spec motorcycles is just as hard for us to get here in America as information about American-spec bikes is for you in Germany. The tech people at the U.S. distributors usually have no detailed tuning information whatsoever about European models, simply because they have no need for it. And even when they do have such knowledge, they generally are unwilling to divulge it. The U.S. distributors are, after all, subsidiaries of the same companies that feel obliged to restrict the power output in the first place; consequently, the practice of telling the public how to circumvent those restrictions is frowned upon. And because we rarely have access to European-spec bikes, we aren’t able to determine the differences ourselves.

We do know that the manufacturers generally use any or all of three methods to lower the power output on European models: 1) altered specifications for valve opening and closing, accomplished either with camshafts that have less lift and/or shorter duration, or through slight re-timing of the same cams found in unrestricted models; 2) a different spark curve provided by the ignition black box; 3) smaller carburetors and/or neckeddown intake manifolds.

Which methods a manufacturer might employ depends upon the amount of power an engine needs to “lose.” A 750 that normally puts out, say, 105 horsepower might get by with a black-box that retards the spark a few extra degrees at high rpm; but a 145-horsepower 1100 might need to use all three methods of detuning to get its output reduced to 100 horses.

For these reasons, we can’t offer any specific re-tuning information about the ZX-11 or the CBR900RR. But our contacts at American Honda tell us that there are no engine-tuning differences between the 49-state VFR750 sold in the United States and the European iteration. So, you can at least take that one off your upgrade list.