Service
SERVICE
The quick and the red
Paul Dean
I own a '92 Suzuki GSX-R750 and a '93 Ducati 750SS. The Suzuki handles superbly under all conditions, no matter the speed or the corner. But the Ducati doesn't, especially at low speed on city streets. I've measured the suspension sag of both bikes and gotten similar numbers. I've played with the Duck’s shock settings (there are no fork adjustments), and raised and lowered the tubes in the triple clamps over a 20mm range. I changed the rear wheel from the 4.5-inch original to a 5.5, and the tire from a 160 to a 170 (it felt better during cornering at speed). I installed a Bitubo steering damper and put fresh oil in the fork. But the slow and lazy response is still there. Could you please explain why? Gerardo Juarez
Queretaro, Mexico
The reason is simple: steering geometry. The 75OSS has a much shallower steering-head angle (28 degrees) and considerably more front-wheel trail (4.5 inches) than the GSX-R (24.5 degrees and 3.7 inches). On paper, that difference might not seem like much; but in the realm of steering behavior, it’s as different as night is from day. And no amount of chassis “tuning” can fully compensate. Only major alterations, such as changing the angle of the steering head and switching to triple-clamps with more offset, could
allow the Ducati to handle anything like the Suzuki at low speeds.
Besides, even if the 75OSS had the very same steering geometry as the GSX-R, it still wouldn’t have the same handling. The Ducati’s V-Twin engine, which isn’t a whole lot wider than a Single, can have its mass positioned much lower in the chassis than is possible with the Suzuki’s wider four-cylinder motor; consequently, the Duck has a significantly lower center of gravity than the Suzuki. But that low eg also caused the designers some concerns
about straight-line instability, so they gave the SS slower geometry than they would have used on an inline-Four machine. What’s more, the layout of the Ducati 90-degree V-Twin engine (in which the front cylinder extends forward) necessitates use of a longer wheelbase than does the Suzuki ’s transverse Four, arid that further contributes to relaxed low-speed handling. Later Ducatis, such as the 916 and 996, have much quicker steering, of course, but the SS models were infamous for their lazy low-speed handling characteristics.
Venting his rear end
I have a 1998 Honda 1100 Shadow ACE that has a problem with gear oil blowing out of the vent in the top of the finaldrive housing at the rear wheel. Not long after I top off the fluid level as specified in the owner’s manual, I’ll check it and always find that I have to add some, and the rear end of the bike is covered with oil. I called the dealer where I bought the bike (80 miles away), and the only response I got was, “That’s what the vent is for.” I ride almost every day, mostly to work and back, 7 miles each way. It’s hard enough to keep a bike clean in the rains of Oregon without having to degrease the rear tire and wheel after each ride. Any help you can offer would be greatly appreciated. Bill Bradford
Otis, Oregon
I spoke with American Honda ’s service people and a few mechanics I know at some large Honda dealerships, and no one had any knowledge of a mechanical problem that would cause oil to blow out of the vent opening on the 1100 ACE.
Indeed, there isn’t even any significant pressure generated inside the gearcase that could force oil out. The normal churning of the oil by the gears might cause some of the lubricant to splash around, but the vent ’s design won’t allow any of it to escape if the level is correct.
One of those mechanics did, however, report that he once had seen oil seeping out of the gearcase vent on an 1100 Shadow when the case had been overfilled; as soon as the oil level worked its way down near its prescribed level, the leakage would stop. He explained that the case had been overfilled because the owner topped off the oil level while the bike was propped in a vertical position instead of resting on its sidestand as stated in the manual. So, although you claim that the oil level on your bike “is as prescribed in the owner’s manual,” the symptoms suggest that the gearcase may be overfilled.
If overfilling clearly is not the culprit, however, I suggest you contact the people at American Honda’s Customer Service Department and explain the
problem to them. Even if they don’t agree to fix it under warranty, they may arrange to have a regional service representative look at the bike to determine the cause of the oil discharge.
Currently challenged
Three months ago, I purchased a 2000 Yamaha YZF-R6. Since then, it has been in the shop three times for the same problem. If the bike sits unused for a couple of days, the battery loses voltage and will not start the engine. The shop has replaced the battery three times, along with the alternator stator and the rectifier. Do you have any solutions?
Hugo Lopez Union City, New Jersey
Obviously, some electrical component is draining the battery when the bike is parked. The R6’s LCD instruments do require a small amount of voltage to retain their memory when the ignition is off but the current draw is miniscule-no more than for a digital watch, the tiny battery in which lasts for years.
If you have an ammeter, a rudimentary understanding of electricity and a little patience, you can probably track down the cause. First disconnect the negative cable of the battery, then connect the negative lead of the ammeter to the terminal on the battery, and the positive meter lead to the end of the battery cable. When the ignition is off, the ammeter should indicate that current is flowing into the electrical system. One by one, disconnect electrical components until you unplug the one that allows the ammeter to read zero. This might seem like a lot of trouble, but it’s the most conclusive way to detect the source of your R6 ’s electrical leak.
Breaking-in is hard to do
I just bought a new Kawasaki ZX-12R and have a question about breaking-in the engine. The dealer says I’m supposed to keep the rpm under 4000 for the first 400 miles, and then under 6000 rpm up to 800 miles. I have several friends who own bikes, and they say I should put about 150 miles on the Kawi while keeping it under 4000 rpm, then ride it the way I plan on riding it all the time-that is, break it in according to my usual riding style, which is more aggressive. They claim that following the factory recommendations will “format” the engine to have less power potential. On the other hand, I read somewhere that I should double the factory recommended break-in period for the ZX-12R because of troubles with its engine. What’s the straight scoop?
Tom Clabough Fremont, California
For starters, Tom, who do you think knows more about the break-in requirements of any new motorcycle, the people who designed, developed and manufactured it, or your riding buddies? If it were my bike, I’d do what the manual suggests.
Just be aware that in this case, the manual has been amended. In a bulletin dated June 2, 2000, Kawasaki revised the break-in recommendations that were printed in the original ZX-12R owner’s manual. Supposedly, this information was sent to every ZX-12 owner, so I’m surprised that you aren’t already aware of this change. The bulletin instructs owners to begin break-in by observing the very same procedure as detailed in the original manual (keep the rpm under 4000 for the first 500 miles, and then under 6000 for another 500), but then adds the strong recommendation that they not rev the engine higher than 9000 rpm for another 1000 miles. The bulletin refers to this second phase as the “transition from break-in to normal operation,’’ but no matter how it’s described, it still amounts to an extended break-in period.
As far as I know, this amended policy is Kawasaki ’s reaction to a single ZX-12 engine failure experienced by a German magazine shortly after the bike’s European release. I’m not aware of any other ZX-12 engine failures either here or anywhere else in the world.
Mileage-minded
I have a 1988 Honda NX650 Single that still appears to have the stock carburetor and exhaust system. Its fuel mileage seems to average around 42-43 mpg at freeway speeds, which is more or less in line with other 650cc Singles. But reading the tests in motorcycle magazines, I notice that the mileage of bikes like the Moto Guzzi Quota, an 11 OOcc V-Twin, is in the low 40s, too. And according to the July issue of Cycle World, the new Kawasaki ZX-9R, which puts out 130 bhp, gets 41.7 mpg; the 94-bhp Triumph Sprint RS gets 42 mpg; and a Honda VFR800, which gets 41 mpg, makes 97 bhp, compared to the miserly 38 bhp of my NX. What’s up with this? Are big Singles just stunningly thirsty beasts?
kurtjen
Posted on America Online
Not really. This isn’t a matter of how much horsepower an engine makes at its peak, but rather how much is required to propel any given bike at the freeway speeds you travel. Despite their considerable displacement and horsepower differences, all the bikes you mention require about the same amount of horsepower-give or take a few ponies based on areodynamic differences-to travel at a steady speed of, say, 65 mph. In the process, they all consume approximately the same amount of fuel. But if you accelerate rapidly or ride at speeds that make the engines run at or near their power peaks, the bigger, higher-horsepower bikes will begin consuming much more fuel than the lower-powered NX.
Is CNC a new network?
A recent entry about Hi-Point wheels in your magazine’s New Ideas department prompted me to write and ask a few questions about manufacturing techniques. What is the difference between “forged” and “cast?” And what is meant by “CNC-machined?” I often see these terms used in various publications and can only guess at their meanings.
Bill Slonecker Gresham, Oregon
Forging and casting are too complex and have too many variations for me to describe in detail, so I’ll keep it simple. When a component is forged, the material from which it is made is either hammered, pressed or squeezed into the desired shape. Sometimes the material is first heated to the point where it becomes very malleable; sometimes it is heated only to the point of slight malleability; sometimes it is not heated at all, depending upon the material and the requirements of the finished part. When a component is cast, its material is heated to the point where it becomes liquid and
then poured into a mold, where it cools and takes the desired shape. Forging usually-but not always-yields a stronger part than does casting, but the process requires costlier tooling and often presents more problems when dealing with complex shapes.
CNC stands for “Computer Numerical Control,” and CNC-machined means that the device (a drill, a lathe, a mill or a purpose-built piece of equipment that combines all three) on which a component is machined is computer-controlled. The computer is pre-programmed with numerical codes that contain the precise instructions for driving the cutting tools. This allows all machining operations to be completely automated and very closely controlled for machining tolerances and finished quality.
May the force be with you
I read your reply to the Kawasaki ZX-10 owner regarding the transmission clunk caused by sticking clutch plates when putting the bike in gear after a cold start (“It just keeps hangin’ on,” July, 2000). Good advice. But what about the old trick of breaking the plates loose by putting the transmission in first gear and rocking the bike back and forth-with the clutch lever pulled in, of course-before starting the engine each morning? I’ve been performing this ritual for more years than I care to remember, starting with a Ducati Diana. Richard Frye Maryville, Tennessee
/, too, have freed many a sticking clutch over the years using that very same method. I didn’t mention it to that ZX-10 owner, however, for two reasons: 1) My intention was to help him cure the problem, not circumvent it; and 2) I didn’t even think about that technique when writing my reply, probably because I haven’t had to make use of it in quite a while. Thanks for reminding me, though. And don’t call me Diana. □
Got a mechanical or technical problem with your favorite ride? Can’t seem to find workable solutions in your area? Maybe we can help. If you think we can, either: 1) Mail your inquiry, along with your full name, address and phone number, to Cycle World Service, 1499 Monrovia Ave., Newport Beach, CA 92663; 2) fax it to Paul Dean at 949/631-0651; or 3) e-mail it to CW1Dean@aol.com. Don’t write a 10-page essay, but do include enough information about the problem to permit a reasonable diagnosis. And please understand that, due to the volume of inquiries we receive, we can’t guarantee a reply to every question.
