Service

SERVICE

Sit up and beg

Paul Dean

What is your opinion about sportbike handlebar risers? I’ve read that they can upset a bike’s steering geometry and have other bad effects. Any time I’m looking to buy a new bike, I’m always concerned about comfort, because that one consideration is very important to me. If putting risers on a sportbike would be okay, then I would be able to give a serious look at a lot more bikes than I currently am willing to consider.

Damian Monteieone Brooklyn, New York

Installing higher handlebars has no impact whatsoever on a motorcycle’s steering geometry. The bike might steer or handle a little differently due to a change of bars, but that would be the result of shifts in the bike’s weight distribution and center of gravity caused by the rider sitting in a more upright position. If the bars are any wider, they also give the rider more leverage when pushing and pulling on the grips. But the steering geometry is what it is, and swapping handlebars can’t change it.

A few companies in the motorcycle business currently market kits that convert a sportbike ’s low, roadracy clip-on handlebars to something more friendly for everyday use. Some retain the clipon attachment style but move the grips higher and/or farther back, while others do away with the clip-on system and simply mount the hand controls on tubular, higher-rise handlebars.

We have either tested or at least tried several such conversions, and so far, we ve never encountered one that created any handling problems. Besides, more and more of the naked bikes that you read about and see are little more than sportbikes minus fairing and fitted with higher handlebars. Usually, the biggest problem with installing higher bars on a fully faired sport machine is getting them to clear the cutouts in the fairing. In most cases, that ’s the one factor that limits the height or rearward sweep of the bars more than anything else.

If you can find a set of higher bars to fit the sportbike of your dreams, go for it. You ’re not likely to regret the move.

Horsepower math test

I read with interest your reply to Ridley R. Reese (“Playing the percentages”) in the August issue regarding gearing changes to his ’97 Honda CBR1100XX, and the resulting effects on torque. The equation for calculating horsepower is: Power equals torque times engine speed divided by 5252. In your reply, you said that if the overall top-gear ratio were 4.5:1, the engine torque would be multiplied by that same factor, 4.5:1; so the engine torque you used in your example, 80 ft.-lb. at 7500 rpm, would be 360 ft.-lb. at the rear wheel in top gear, “less frictional losses in the drivetrain.” My question is, what happens to the power equation? Does it no longer apply? At the engine, 80 ft.-lb. at 7500 rpm works out to 114 hp (80 x 7500 + 5252). But if we use the rear-wheel torque of 360 ft.-lb., this equation would give us 514 rear-wheel horsepower. So, what’s the solution here?

Gregory P. Katchin Richmond Hill, Ontario, Canada

Excellent question, Gregory, and the answer is quite simple: When calculating horsepower, the torque and rpm readings are always taken at the same location. If the torque reading is at the crankshaft, that figure is multiplied by the rpm of the crankshaft. If the torque is measured at the rear wheel, that figure is multiplied by rear-wheel rpm. So when calculating horsepower using rear-wheel rpm, you not only multiply the engine’s torque figure by the overall gear ratio, you also divide engine rpm by the same factor. If using the same hypothetical example as before, you divide 7500 by 4.5, _ you get 1667 rearwheel rpm. So, multiply 1667 by 360 and divide by 5252. That works out to 114 horsepower, the same figure we got when using engine torque and rpm. In reality, the rear-wheel torque and horsepower figures would be lower than those obtained at the crankshaft because of frictional losses in the drivetrain but that only affects the ant number, not the method calculation.

Let my Cameron go

If you wouldn’t mind, I’d like to pose two questions for Mr. Kevin Cameron: 1) If Ducati has been so successful with its desmodromic valve technology, why aren’t other manufacturers copying (stealing) it? 2) How is it possible that a “frameless” bike that uses the engine as a stressed member doesn’t shake itself apart, while other bikes that do have frames are subject to engine vibrations that negatively affect handling? Larry Charbonneau

Fullerton, California

No, I don’t mind at all. I forwarded your questions to Kevin, who responded to them as follows:

“Mercedes raced its W-196 F-l car with a desmo Straight-Eight engine in 1954 or thereabouts. Norton built a desmo head for the Manx Single but found no advantage at those engines ’ rpm levels. A lot of WWI aero engines had valve-return ‘stirrups ’—a kind of crude back-up desmo system in case of spring breakage. More recently, Cosworth built desmo heads for one of its F-l car engines but did not pursue the idea. Ducati is really the only place in the world where a fully developed and reliable desmo system exists, and they have proved it is the equal of anything in the new MotoGP class.

“One of the things that had to happen before the present generation of solidmounted engines in aluminum or light steel-tube ‘trellis ’ chassis would be practical was to seriously reduce engine vibration. The worst vibrators, like the British-styleparallel-Twins, have been discontinued. Low-vibration types, such as 90-degree V-Twins, smaller inline-Fours and balance-shaft-equipped narrowerangle V-Twins, have taken their place. Larger inline-Fours are sometimes equipped with secondary balancer shafts. Ducatis 90-degree V-Four is likewise a naturally low-vibration engine configuration. This makes it possible to bolt these engines to chassis that would not have lasted through the afternoon with the vibration of some bygone types."

FEEDBACK LOOP

In the October, 2003, issue, M. Nerón wrote about an electrical problem (“Later, stator”) with his ’93 Honda CBR900RR. I experienced the very same light/heat issue on my ’93 900RR. The problem lies with a burned and corroded AC generator connector that comes out of the stator. Honda has recognized this problem and makes a handy charging-system repair kit (part no. 31105-ML8-305) that contains instructions and all the hardware needed to replace the connector. After the fix, voltage to the charging system was restored, the wires no longer got hot and my lights stopped fading in and out. Ken Holmes

Renton, Washington

Thanks for the heads-up. Mr. Nerón will appreciate the advice-although all of his riding buddies will deeply miss the warm glow of his stator wires guiding them down the road like a certain Red-Nosed Reindeer.

Loose, tight, just right

I’m the original owner of a 1999 Suzuki SV650 that has 3000 miles on the odometer. I recently adjusted the chain to the factory measurement, and when I rolled the bike forward about a foot, the chain tension loosened compared to the previous measurement. I rolled the bike back to the spot where I had adjusted the chain and the tension was right on. Then I rolled it about two feet forward and the chain got tighter. Someone told me that the chain had a tight spot, so I replaced it with a new RK O-ring chain, but that did not fix the problem. The axle-adjustment marks on the swingarm are aligned equally on both sides, and the sprockets look fine. What is going on here? Sonny Sli

Torrance, California

Your SV’s sprockets may lookfine, but one of them is out-of-round. Based on your report that the chain goes tight-loose-looser over a span of about two feet, L suspect that the offending sprocket is the rear one. Here’s how to make sure: Carefully and > slowly roll the bike to the point where the chain is the tightest, then, using a piece of chalk or a grease pencil, draw a short, horizontal line on the rear sprocket at its rearmost point, exactly at the 3 o ’clock position. Now roll the bike to the point where the chain is the loosest and make another mark at the 3 o ’clockposition on the rear sprocket. If the two marks are even remotely close to 180 degrees apart, this tells you that the rear sprocket is out of round. On the other hand, if the chain tightens and loosens two or three times during just one revolution of the rear wheel, the front sprocket is out-of-round. The offending sprocket could have worn unevenly or even been manufactured out of round, but in either case, it will have to be replaced.

TOOLTIME

otorcycles are magnificent examples of creative packaging. You really can appreciate the ingenuity and effort it took to cram so much stuff into so little space—until, that is, you have to peer into one of those tiny nooks or crannies in the dark of night or the dim of a garage. That’s when you find that you can’t get your hand, your flashlight and at least one of your eyeballs all to focus on the same spot at the same time.

I’ve solved that problem with a Streamlight Stylus Reach, a clever little penlight that has an incredibly bright LED bulb at the end of a 71/2-inch-long flexible cable. I’ve not yet found any place that this light could not, er, “reach” into and illuminate, and I’ve even been able to bend the cable into various shapes so the light would hold itself in place while I worked in a tight area. The Reach will run on its 3 AAAA batteries $ for up to 60 hours, and the LED bulb is claimed to last for . 100,000 hours-the equivalent of leaving the light on continuously for 11Vi years. The Reach sells for about $20 at tool outlets and hardware stores, but if you can’t find one, log o nto www.streamlight.com to locate a retailer near you. -Paul Dean

Hot Wings, anybody?

I wrote you some time ago regarding the well-known overheating problem with the Honda 1800 Gold Wing, as did Niles Slemmer, whose letter you answered (“Wings of warm”) in the March, 2003, issue. In your response, you said that Honda had acknowledged the problem and promised to have a fix by summer, but to date, I have heard nothing. Has Honda come forward with a solution or does this problem persist? John Griffith Posted on www.cycleworld.com

If you own an 1800 Gold Wing, you must not be the original purchaser; Honda has notified every GL1800 owner of record and informed them of the free remedy that is available. This past March in Daytona, the company also held a “town hall meeting” with GL1800 owners on this subject. Honda even got word of the meeting out to owners by advertising in various Gold Wing club newsletters prior to the meeting.

In any event, the free fix for the overheating problem involves the installation of a new engine control module (ECM), along with a check of the entire cooling system to ensure that there are no blockages anywhere along the line. When the replacement program began in June, there was a shortage of revised EC Ms for a while, but they are in ample supply now, so no one should have any problems obtaining one at their dealership.

As you no doubt know, the overheating seemed to surface most often when the bike was being ridden slowly, usually in first gear. The new ECM is programmed with different ignition-timing parameters, particularly in first gear, and Honda insists that this is a 100-percent fix for the problem. □

Got a mechanical or technical problem with your beloved ride? Can’t seem to find workable solutions in your area? Or are you eager to learn about a certain aspect of motorcycle design and technology? Maybe we can help. If you think we can, either: 1) Mail a written 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 949/6310651; 3) e-mail it to CW1Dean@aol.com, or 4) log onto www.cycleworld.com, click on the “Letters to the Editor” button and enter your question. Don’t write a 10-page essay, but if you’re looking for help in solving a problem, do include enough information to permit a reasonable diagnosis. And please understand that due to the enormous volume of inquiries we receive, we cannot guarantee a reply to every question.