Service

SERVICE

Paul Dean

HECTOR CADEMARTORI

Desmo din

Last February, I bought a beautiful 1996 Ducati 900SS with just 90 miles on the clock. It belonged to a 65-year-old guy who owns seven other bikes and only rode the Ducati three times. I have a lot of technical experience and have owned (and maintained) many motorcycles, but I’m worried about a valve noise on my Ducati. I can hear the valves “ticking,” mostly between 3000 and 5500 rpm under slight load. The tick occurs in both cylinder heads and at the same noise level. At 600 miles I inspected the valve clearances, which all checked out fine. The bike now has 1900 miles on it and runs great. The ticking has not gotten any worse, but it’s still there. Is it normal to hear the valves make this kind of noise or should the engine run more quietly?

Jan Vente Posted on www.cycleworld.com

Without being able to hear the noise myself, I can’t say for sure if there are problems in the valvetrain. But I can tell you that the desmodromic valve system, which is exclusive to Ducatis, is noisier than a conventional system. While other engines use cam lobes to open the valves

and rely on springs to close them, the desmo system uses separate cam lobes to both open and close the valves, thereby eliminating the need for valve springs. Since there is no spring tension for the cams to overcome, the desmo arrangement reduces valvetrain friction; and be-

cause the valves are opened and closed mechanically, they cannot float. But the system does also result in slightly more valve noise. As long as the bike runs well and the valve clearances remain within the prescribed tolerance, don’t let the ticking noise give you an ulcer.

Synchro de Mayo

I have a 1999 Honda CBR600F4 that is having some shifting problems. The bike has just over 8000 miles on it and has gotten kind of hard to shift into second gear. Sometimes it jumps back out of gear after I get it into second, especially if I’m accelerating pretty hard. Lately, it also has started jumping out of second right after I downshift from third. I’m not a mechanic, but I’ve gotten all kinds of opinions from some of the guys I ride with on weekends. One of them says the shift mechanism needs to be adjusted, another claims that the synchros are shot, and another F4 rider says the shift forks are bent. Who should I believe, or are they all wrong? Eduardo Mayo Austin, Texas

“Synchros?” You need to inform the guy who suggested bad synchros that motorcycle transmissions do not contain such things. Synchros is short for “synchronizers,” which are transmission-shaft friction rings that match gear speeds to allow smooth, quiet gearchanges. Standard-shift automobile transmissions use synchronizers, but all motorcycles have gear-dog transmissions that employ an entirely different method of engagement. I strongly suggest you never again believe anything that guy tells you!

Your F4-riding buddy, however, was right on the money: The second-gear shift

fork in your CBR is either bent, badly worn or both. This condition usually results from ongoing abuse, be it full-throttle power shifting or grossly mismatching engine speed and rear-wheel speed while shifting either up or down. But no matter the cause, the cure will involve an expensive repair job requiring removal and disassembly of the engine to allow access to the transmission internals.

Tube be or not tube be

I have owned and ridden Yamaha Viragos for many years, and they all have been equipped with tubeless tires. Since Yamaha has stopped making Viragos except for the 250cc model, this year I was forced to purchase a V-Star, which has tube-type tires. The bike handles as well as or better than the Virago, but I’m wondering why Yamaha decided to go to tube-type tires. And is this type better or worse than a tubeless tire? Ron L. Gagnon Posted on America Online

Yamaha ’s use of tubed tires on the V-Star models was dictated by wheel types. The 750cc and llOOcc Viragos use cast-alloy wheels, which are suitable for tubeless tires; to achieve the desired retro-cruiser look, however, the V-Stars were fitted with wire-spoked wheels, which require tube-type tires. A cast wheel has a solid rim area that keeps air fully contained,

but the spoke-nipple holes (48 on each wheel of a V-Star) in the well of a wirespoke rim are unable to prevent air from escaping. Certain BMW models mate tubeless tires with wire-spoked wheels, but they do so with a unique, proprietary rim design that locates the spoke nipples at the hub, and the spoke heads outside the bead of the rim.

As far as handling, ride quality, grip and tread mileage are concerned, there is little meaningful difference between these two types of tires. There is one distinct advantage of tubeless tires, however, and that’s their tendency not to “blow out” as tubed tires sometimes do. When a tube is ruptured by a puncture, the escaping air can make a rapid departure from the tire ’s interior through all the holes in the rim, but on a tubeless tire, the air can only exit through the puncture. Thus, a tubeless tire generally gives the rider a better advance warning that it is about to go flat.

Squeakin’ Eagle

I’m having a bit of a problem with my 2001 H-D Road King. The bike has 6500 miles on it and has been slightly modified with an exhaust system, air cleaner and remapped fuel injection, all of it from Harley’s Screamin’ Eagle accessory line. At about 4000 miles, the bike began making a high-pitched squeaking noise when I would roll off the throttle while the engine was cold; it never did it once the engine got warm. But the noise has steadily gotten worse, and now it even happens between shifts. The noise seems to be coming from the front motor mount, but I’ve checked it and have not found anything wrong. Any help you could provide would be welcome. Martin L. Rudolph Compton, California

The front motor mount indeed is the source of the problem. The FL has an unusual front mount that allows the engine to move very slightly under the forces of acceleration and deceleration. When the interacting surfaces of the mount get dry, that movement can cause the very kind of highpitched squeal you describe. This occurs quite often with FL models. Fortunately, the remedy is quick, easy and cheap: Squirt some silicone spray on the motor mount and the noise should vanish.

Can you spell "obvious”?

I own a 2000 Kawasaki Ninja 250 and was thinking about installing a Muzzy exhaust system on it. On Muzzy’s website, as well as on some other web pages I’ve seen, it says that the carbs need to be rejetted if I change the exhaust or else the valves might burn up. But when I asked the people at

my local Kawasaki shop about this, they said that no jetting is required! A little clarity from an expert on the matter would be appreciated. Also, if I do use this exhaust, should I go ahead and replace the stock intake with filter pods, as well?

Paul Escamilla Posted on www.cycleworld.com

Who do you think has more expertise in the requirements of a Muzzy exhaust system for a Kawasaki, the dudes down at the local Kawasaki dealership or the company that designed, developed and manufactured the system-the same company that operated Kawasaki ’s roadrace and drag programs for many years?

Fact is, even if you don’t replace the stock exhaust, your Ninja will start easier, warm-up sooner, respond better and accelerate more quickly if you install a jet kit. Like virtually all small-displacement streetbikes, the 250 Ninja is sold with extremely lean carburetion that meets federal emissions regulations, so fattening up the jetting does wonders for its overall performance.

Also, I suggest that you not replace the stock air cleaner with separate filters. The large volume of the stock airbox plays a very important role in engine tuning. Re-

placing it with individual filter elements might help improve intake breathing in one specific rpm range, but it will hurt performance at all other engine speeds.

Speed Bandit

I have a stock 2001 Suzuki Bandit 1200. Your October, 2000, issue put the bike’s top speed at 144 mph, and the June, 2001, issue says it is 145 mph. I have had mine register 168 mph on the speedometer, and it still had a little bit left. Can the speedo be off that much or is my bike a freak off the assembly line? Larry Easley Posted on America Online

The only way your 1200 Bandit is going to reach 168 mph is for you to drop it out of an airplane flying at high altitude! Even then, it still might not achieve that kind of speed unless it falls nose-first all the way.

All of our top-speed figures are obtained by riding the bikes past a high-end, calibrated radar gun at maximum velocity. During those runs, the speedometers always read considerably higher than the actual speed. The disparity with your bike ’s speedometer is a bit greater than usual, about 15 percent, but we have seen that same degree of optimism on a few other bikes. Besides, the amount of additional horsepower required to raise a Bandit 1200’s top speed from 145 to 168 mph is enormous, many times more than could ever possibly result from variations in accumulated manufacturing tolerances.

So, no, your Bandit is not a 168-mph speed freak. Your speedo is simply lying to you. Big time.

Three-mile limit

My 1986 Honda VFR750F has a mysterious, intermittent problem. About three miles into a ride, the bike occasionally will lose power over the course of about 10 seconds, then eventually stall. The engine will not restart for about one full minute, no matter what I try, but after that, it will start and run fine for the rest of the trip. The problem seems to occur most often when the air is cool, though it has happened on warm days, and the visible electrical components continue to function throughout it all. This isn’t a serious problem, and now, fully expecting it, I am sometimes able to coast long enough to restart the engine without ever pulling over. Still, I’d like to figure out the cause and remedy it. I would be most grateful for any suggestions you might offer.

Nicko Christenfeld Posted on www.cycleworld.com

Let ’s start by determining what the cause is not. It’s not in the main power supply-i.e.. loose battery cables, intermittent main fuse contact, etc—because so many other electrical components continue to work when the engine stops running. And we can eliminate the ignition coils, since the VFR has two of them, meaning there is absolutely no chance that every occurrence of this problem is the result of both coils malfunctioning-and recovering-at the very same instant. The VFR also has two ignition pulse generators (the sensors that trigger the spark) that are not likely to stop and start working in unison. So if this problem is ignition-related in any way, it would seem to be either in the ignition control module (the “black box’), the ignition switch or the kill switch on the right handlebar.

To troubleshoot these electrical components, get your hands on a shop manual and study the wiring diagram therein. If you ’re any good with simple electrical wiring, you can temporarily jump the ignition switch, then take a few test rides (hey, you ’ll only have to travel about three miles per ride) to see if the problem still occurs.

Do the same with the kill switch. The ignition control module is more of a problem, though, since all of the usual troubleshooting tests described in the shop manual won’t help you pinpoint an intermittent problem like this one. Instead, you might try temporarily wiring either a voltmeter or a small lightbulb to one of the wires that run between the module and either of the ignition coils, then tape it where you can see it while riding. If the voltmeter ’s reading fluctuates wildly or drops to zero when the engine starts faltering, or if the light flickers irregularly or goes out altogether, you ’ll know that the module is at fault.

If the problem is fuel system-related, it would have to be in the fuel tank or its petcock. The VFR has four carburetors, so once again, the chances of all four simultaneously malfunctioning are astronomical. The cause is more likely to be a temporary blockage in the main fuel line—although I must admit that I don 't know why such an obstruction would occur only during the first few miles of a ride. But to determine if there are problems in this area, go on a test ride and carry along the tools needed to get at and remove any of the carburetor float bowls. As soon as the engine stops running altogether, immediately turn the fuel petcock to Off, then remove one of the float bowls to see if it contains any gasoline. If it does not, or if the fuel level is very low, you ’ll know that a fuel-delivery problem is the culprit. If you use this kind of logical process of elimination, sooner or later you will discover the cause of the problem.

Got a mechanical or technical problem with your beloved ride? Can’t seem to find reasonable 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; 3) e-mail it to CW1Dean@aol.com, or 4) log onto www.cycleworld.com and click on the Feedback button. Always include your name, along with your city and state of residence. 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 huge volume of inquiries we receive, we can’t guarantee a reply to every question.