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I recently purchased a mint 2005 Yamaha FZ-6 with 6000 miles on it. The bike rides great except for one problem: When lightly applying the front brakes, I often get a terrible shuddering from the front end. It feels like the front tire is hopping up and down. This problem seems to occur most frequently when I’m braking on rough pavement, and especially when making a sharp turn while braking. I’ve changed the front tire and checked the steering-head bearings by trying to move the fork legs while the bike was on the centerstand. Everything seems okay. Could the steering-head bearings wear out so soon? All of the FZ-6 Internet forums talk about this issue, but nobody seems to have a fix.
We turned this one over to Jeff Stern at Fastline Performance in Las Vegas, Nevada (www.fastlinetuning.com). A seriously fast veteran roadracer and one of the best diagnosticians we know, he takes the systematic approach, ruling out potential causes from the steering head down.
“Checking the steering head is a good idea, but loose bearings wouldn’t typically cause this type of issue,” Stern says. “If this motorcycle came into my shop, I’d take a test-ride to verify the complaint. Then, with the bike on a front-end stand, I’d make sure the tire wasn’t out-of-round, and check for flat spots, tweaks, divots or anything that would indicate damage. I’d also verify that the tire was properly balanced. Next, spin it and listen to the brakes. If one rotor touches the pads in the same spot as it goes around, the bike probably has a bent rotor.
"After that, I’d check both brake rotors using a dial indicator to measure runout, and clean them. Excessive brake-lever travel is another telltale sign, because a bent rotor will push the pads and pistons back into the caliper.
“If the rotors have ever been removed for any reason, remove them again to look for any debris that may have gotten trapped between the mounting surface and the rotors. Try using use a whetstone to clean up the mating surfaces, and then reassemble everything to spec and check runout again. If excess runout is still detected, check the disc mounting surfaces on the wheel with the dial indicator to make sure they are within prescribed tolerances. After all that, you’ll also need to make sure that everything you’ve removed is properly reinstalled and torqued to spec.”
Do Loud Pipes Really Save Lives?
Is it safer to have loud pipes or not? I have a strong feeling on the subject, but I don’t know of anyone who has done any serious investigating. Some real facts in accident rates would be good.
Don’t believe everything you read on a bumper sticker. According to the Motorcycle Safety Foundation, there is no empirical basis for the claim that loud pipes make motorcyclists any safer. For starters, the definitive Hurt Report says 77 percent of trouble comes at you from the front, so those muzzles are aiming all that racket in the wrong direction. Smart riding and brightly colored riding gear save lives. Loud pipes are a tiring distraction, drowning out sirens, horns, skidding tires and other sounds that might warn their hearing-impaired advocates of impending doom. On top of that, they make countless enemies, some of whom wear badges and write tickets or have the power to influence unfriendly legislation. So keep a lid on it.
I’ve noticed some helmets on sale at closeout prices online. A customer review stated he bought one that was stamped with a 2005 manufacturing date. Is it advisable to purchase helmets out of old stock? Does the five-year rule apply even if the helmet has been sitting in a box all that time?
That depends on what brand of helmet you’re talking about. Arai, for instance, warrants helmets for seven years from the date of manufacture, and five years from the date of first use. An Arai helmet that had been languishing in the box for five years would have another two years of life left in it. If the helmet in question is Snell-approved, however, we would advise you to choose one that meets the new M2010 standard over the old M2005. It really does make that much of a difference.
Why do so many bikes have heavy bar-end weights? Would removing them cause any performance issues?
The primary function of bar-end weights is to lower the resonant frequency of your handlebars below that of normal engine vibration. Adding a precise amount of metal at or just beyond the end of the bar dissipates vibration instead of allowing it to accumulate and trigger the sort of sustained ringing you get from striking a bell. In most cases, removing said weights or replacing them with lighter aftermarket versions allows vibration to accumulate unchecked, often with uncomfortable results.