Er Road Racin

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Pulling the plug

QHow safe is patching or plugging a tire? Is it safe enough to do trackdays? Mark McQueen

Rocklin, California

A Absolutely, positively not; don't even think about it. Matter of fact, aside from attempting a top-speed run at Bonneville or running flat-out around the NASCAR oval at Daytona, riding at a trackday is about the worst thing you could do with a plugged tire.

Several factors make a plugged tire potentially dangerous. For one, no two tire punctures are exactly the same, so you have no way of knowing if or how badly the tire's carcass may have been damaged. I've seen punctures that look like nothing more than a clean, innocent little hole in the tread; but when the tire was subsequently cut apart and analyzed, quite a few of the cords in the circumferential belts initially had been severed, and even more evidently came apart after the tire was run a short distance at highway speeds. If the tire had been kept in service much lon ger, it would have suffered a major— and probably sudden—failure.

What's more, since you don't know anything about the condition of the hole down below tread level, there is no guarantee that a tire plug will remain in place once the tire is put back into use—especially on a racetrack. Tires run at abnormally high operating temperatures on the track, and that can cause the rubber cement that holds the plug in place to soften and lose some of its grip. Plus, the carcass undergoes considerable flexing as it holds the bike on line in corners, and that can further loosen the plug. Making things even worse is that a tire spends most of its track time spinning at high speeds, so there is considerable centripetal force constantly trying to fling the plug out of the tire. If all of this isn't a recipe for disaster, I don't know what is.

Tire manufacturers strongly recommend replacing a plugged tire as soon as possible and that it should never be ridden long distances or at high speeds. Many riders believe that the tire companies say this simply because they want to sell us more tires, but I can assure you that this is not the case. They don't just manufacture tires, they also test them under all manner of possible conditions, so they know firsthand that riding on a punctured tire is a crapshoot. Yes, the tire may continue to perform flawlessly until it is completely worn out; but if it doesn't, if it fails suddenly and catastrophically, who do you think stands to lose the most, you or the tire company?

Trackday? Until you spoon on a new tire, fuhgeddaboudit.

Trail guide

I am considering getting a new bike, so I've been studying a lot of specs, and I have to ask: What the heck are rake and trail? Actually, I think I understand rake, but why do bikes have so many different trail numbers? Dave Fedeler

Columbia, Missouri

A Motorcycles have such varied front-wheel trail dimensions because every model of motorcycle

is sufficiently different in its weight, length, weight distribution, center of gravity, engine design and intended use to warrant a front-end geometry best suited to each individual package.

At the risk of oversimplifying what is a relatively complex matter, rake is the need for a fork, given its basic design, to be set at a kicked-out angle (on production bikes, somewhere between the low 20-degree range to the mid-30s) so it can absorb the impact of bumps as effectively as is reasonably possible. The bumps want to push the wheel directly upward, but the motorcycle is moving forward on a horizontal plane; the best solution is a compromise between those two forces—a force "vector," it's called—resulting in the rake angles you commonly see.

Trail, meanwhile, provides the self-centering effect of the front end. In the automotive field trail is called "caster," since it acts just like the casters on movable furniture, toolboxes, serving carts and many other common items. In fact, were it not for rake, the front ends of motorcycles might look a lot more like those casters.

When engineers configure new motorcycles, they use their knowledge, their experience and in many cases, a sophisticated computer program to decide a starting point for rake and trail. But once that bike gets far enough along in development that it can be ridden, those initial dimensions are altered often many times, based on the feedback the engineers get from the test riders. Sometimes, even other key elements of the prototype bike—the location of the engine, the positioning of the steering head the length of the swingarm or the location of the swingarm pivot, to name just a few—might have to be changed when test riders report that no combination of rake and trail is providing the confidence-inspiring "feel" that is so critical to any motorcycle's performance. When you take into account all those varied and often unpredictable factors, it should be easy to see why trail numbers are inconsistent from one bike to another.

The vapor caper

Ql have a bit of a problem with my 2005 Honda XR650L. When the engine gets hot, it wants to stall when idling. It usually does this at stopsigns and stoplights when I ride on-road but it does it off-road too.


Tools that accomplish more than one task at the same time grab my interest in a heartbeat. It's no wonder, then, that I recently bought a nifty Digital Tire Inflating Gun (part #92570, S49.99) from Griot's Garage ( There's nothing new or revolutionary about a gauge that allows you to simultaneously inflate a tire and check its pressure, but this one is particularly well done. For starters, it's digital, with a large LCD readout that displays pressures in 0.5-pound increments; there's even a back

light that can be switched on for use at night or in dark areas. To protect the gauge against the shock of bumps and accidental drops, the display is surrounded by a soft rubber hood. At the end of the gauge's 141/2-inch-long filler hose is a locking air chuck that clips onto the valve stem for no-hands use,

I can't speak for anyone else, but I really dislike using files that haven't been fitted with handles. My usual objective, after all, is to use a file's teeth to trim unwanted material off of something, not to use its sharp, pointed tang to machine skin from my fingers and palms.

Problem is, most file handles aren't very durable. They're usually made of wood, and the mere act of jamming a tapered tang into their opening tends to weaken the wood right from the get-go. Add in the considerable force that often is applied through the handle, combined with a couple of "oops!" drops on a concrete floor, and you soon can include splinters—and an unusable handle-to the carnage.

But not if you use these handles from Graham Tool Co. (

and the base of the handle has a l/i-inch NPT fitting that accepts a standard air-supply hose or a quick-disconnect fitting.

When you turn on the gauge and clip the filler hose on the valve stem, the readout displays the current pressure just as does any other digital gauge. If the pressure is too low, squeeze the trigger all the way to the handle to add air; when you let off, the new pressure is displayed. If the pressure is too high, you squeeze the trigger only partway, as the first part of its travel activates a bleeder valve. This makes routine tire maintenance much easier and quicker, since you don't have to keep switching back and forth between a filler hose and an air gauge when trying to achieve the desired air pressures.

I have a number of nice tire-pressure gauges in my garage at home, but since I got this one, the others seem to be collecting a lot of dust.

They're made of unbreakable blue plastic with a textured ergonomic surface for a sure grip, and they incorporate molded-in, tang-gripping inserts made of tempered steel. Each insert consists of two threaded sections of different diameters that not only hold a tapered tang with nut-and-bolt tenacity, they allow the handle to be reused on another file; you just unscrew it from one file and thread it onto another.

Graham offers the handles in eight different sizes scaled to fit all types and shapes of Swiss Precision and American Pattern files. They're available either as a complete set for S39.95 (which includes free shipping) or individually for $4.95 each. A detailed fitment chart on Graham's website lets you know which handle would be best suited for any given file.

I've tried turning up the idle speed, but then, if I rev the engine, it takes a long time to come down to idle when I let off the throttle and idles way too fast. The engine runs okay otherwise, and until a month ago, it never acted this way in the 6500 miles I've put on it since buying it barely used (only 450 miles on the odometer) three years ago. My friend says he thinks the problem is vapor lock. What do you think? Terry Peterson Sunnyvale, California

A Whatever might be wrong with your dual-purpose Honda, it's almost assuredly not vapor lock. That's a condition that usually occurs with a system in which the fuel is stored in a remote tank and must first be drawn to the fuel pump via the suction generated by one side of the pump and then delivered to the carburetor by the pressure side of the pump. This is the case with older automobiles that had a carburetor, an engine-driven fuel pump and a gas tank six or eight feet distant at the rear of the vehicle. Vapor lock would occur when engine and/or exhaust heat would cause the fuel in the lines between tank and pump to vaporize. The pumps were able to draw liquid but not vapor, so the engine would stall due to lack of fuel and not restart until the vaporized fuel cooled and returned to liquid form.

Fuel-injection systems have all but eliminated vapor lock because their pumps are located in the fuel tank where they "push" fuel to the injectors rather than pull it. If vapor forms in the lines, the pressure of new fuel entering them drives it out through the injectors, perhaps resulting in a momentary "hiccup" but not a stall.

Largely the same thing happens with gravity-feed fuel systems, such as the one on your carbureted XL-R. The weight of the fuel in the tank thrusting down through the system generally pushes any vapors into the float bowl, where they either return to a liquid state or escape through the vent line.

Instead I think your Honda's stalling issues are the result of a lean idle mixture or valves (either intake or exhaust) that have lost all of their clearance. A lean idle mixture could be caused by an air leak at the intake manifold, either at the O-ring that is sandwiched between the manifold and the cylinder head (item #14 in the accompanying parts illustration) or at the rubber carb-mount boot at the rear

of the manifold. If you carefully spray a little WD-40 around those two joints while the engine is idling, white smoke exiting the exhaust system would be irrefutable evidence of an intake leak.

If an air leak is not the culprit, your XL-R may have a plugged idle fuel jet in the float bowl. If so, don't even try to clean that tiny orifice; simply replace the jet, and do so with the next-largest size.

To meet emissions requirements, the idle mixture already was lean when the bike rolled off the assembly line, so going up one size would improve the idle in any event.

If neither of those two conditions exists, you'll then need to check the valve clearances, which should be .004-inch for the intakes and .005 for the exhausts. Even one zero-clearance valve could cause the stalling problem you describe. Just be sure to make this clearance check as soon as possible, because continued running with a tight valve could damage that valve enough to require replacement.

Breaking the mold

Ql recently replaced the tires on my '01 Suzuki SV650 with Bridgestone BT016s, which the dealer suggested as being significantly stickier than the OEM rubber. When I picked up the bike, the installer told me about the residual coating on new tires that

Best Used Bikes

Triumph Bonneville

Years sold: 10 (2001-present) MSRP new: $6699 (2001) to $8899 (2010) Blue Book retail value: $3235 (2001) to $7590 (2010)

Basic specs: A standard-style parallel-Twin in either 790cc or 865cc displacements making horsepower in the fifties, torque in the forties and posting quarter-mile times in the high- to mid-13-second bracket. Why it won: Though this modern reincarnation of the legendary Bonneville has sold well and won countless diehard fans around the world, it has never managed to win a CI/VTen Best Award. It seemed to be star-crossed in that regard, because any time it was a contender, it always got edged out by some other bike in its category that had just a little more of something special going for it. But that does not diminish the character or excellence of these machines, which combine the experience of riding a timeless classic with the quality and reliability of modern technology.

The first "new" Bonneville was a 790cc carbureted model that arrived in 2001 as the sole Twin in the company's lineup. The model spread to three variations in 2002, four in '03 and five in '04, including one, the Speedmas-

ter, having its displacement bumped up to 865cc. In 2007, all six of the parallel-Twin models got the larger engine, and by 2008, the line had expanded to eight fuel-injected models. No, they all are not called Bonneville, but they are close variations based on the same engine and basic chassis design. Useful resources: If you type "Triumph Bonneville" into your browser's search engine, you'll come up with about a gazillion entries—clubs, forums, road tests, parts and accessories, for-sale classifieds, hop-up equipment, you name it. Many of those sites are devoted to the original Bonneville, of course, but you'll likely find just about anything imaginable on-line related to the new-gen Bonnies.

Recall Roster

NHTSA Recall No. 10V356000 Manufacturer: Ducati North America Model: 2010 Multistrada 1200 Number of units involved: 396 Problem: The throttle cables may come into contact with the upper edges of the radiator during normal operation, which could cause the cables to become chafed. Damaged cables could adversely affect throttle operation, reducing the rider's ability to control the motorcycle and increasing the risk of a crash. Remedy: Dealers will secure the throttle cables to frame above the radiator to prevent contact.

NHTSA Recall No. 10V358000 Manufacturer: Ducati North America Model: 2010 Multistrada 1200 Number of units involved: 196 Problem: During production, an incorrect screw may have been installed in the steering head. This could cause the steering head to become loose during normal operation, adversely affecting the rider's ability to control the motorcycle and increasing the risk of a crash. Remedy: Dealers will replace the affected steering-head screw with the correct screw.

NHTSA Recall No. 10V357000 Manufacturer: Ducati North America Model: 2010 Multistrada 1200 S Touring Number of units involved: 495 Problem: The centerstand mounting screws may come loose during normal operation, which could cause the stand to become displaced from its intended mounting position. This could adversely affect the rider's ability to control the motorcycle, increasing the risk of a crash. Remedy: Dealers will remove the centerstand screws, apply thread-locking compound and reinstall the screws to the specified torque. Owners not receiving any of these three free remedies can contact Ducati at 800/962-7926.

Candid Cameron

^^ My question is in regard to oil. I recently purchased a new BMW F800GS, and one of that bike's upsides for me was being able to change the oil easily (spin-on filter that is accessible). My dealer says that I need to use a 10W-40 "motorcycle grade" oil. Why is this necessary? I have always used the "Made for high-rewing engines" brand in my smaller-displacement cars. If that oil is SE (gasoline) rated, why is it necessary to have a motorcycle grade? And when is a 10W-40 oil not a 10W-40 oil?

Brian Eddy Columbus, Ohio

A What they mean by a motorcycle-grade oil is one that contains useful amounts of the anti-wear additive ZDDP (zinc dialkyl dithio phosphate). Automotive oils of recent API categories have had their ZDDP content reduced because the zinc could, especially in older engines with failing piston rings, reach the catalytic con verter and destroy its function. In place of that anti-wear additive, automotive oils now contain "friction modifiers," which used to be called oiliness additives. These employ fatty acids to form a surface layer on parts (I think of it as "grass," because one end of the additive chain bonds to the surface) that has a friction-reducing effect. Such additives have been implicated in starter-clutch slippage in motorcycle engines, along with a few other issues.

It's true that many bikes now have catalytic converters, but the low-zinc formulation is based on the idea that cars are more likely to wear out in service. In most states, cars are regularly smog-checked, and their emissions equipment, by law, must remain functional for 100,000 miles. Motorcycles are not smog-checked or subject to those same mileage regulations, so the use of ZDDP in their oils is not problematic. In the end, the decision is up to the user.

—Kevin Cameron the manufacturer uses to help release the rubber from the mold when the tire is made. He warned that the residue makes the tires very slippery for the first 100 miles or so, and that I needed to wear it off naturally by riding carefully, avoiding aggressive lean angles. My questions: 1) Are there no effective methods of removing this coating faster (unnaturally); and 2) how does a rider wear off the outer surfaces of the tire "naturally" without actually leaning to that angle? Mark Teragawa

Shoreview, Minnesota

A Although new tires from some companies, including Bridge-stone, are indeed coated with "mold release" that must be worn off before the rubber can provide full grip, that dealership employee's lOO-mile stipulation is misleading. Mileage is not the criteria here; you could ride 100 miles or more on a typical Interstate or open highway, for example, and still have untouched mold release on the sides of the tires. Instead the best way to remove mold release is to ride at moderate speeds and casual lean angles at first, gradually increasing your speed and amount of lean just a few degrees at a time. This ensures that as you progressively lean farther and farther, the largest part of the contact patch at any time consists of rubber that has already had the mold release scuffed off, thereby providing sufficient grip to prevent the tire from sliding. With this technique, you can prep a new tire for all-out cornering duty in 10 miles or less, depending upon the riding conditions.

A new tire actually provides decent grip before the mold release has been scrubbed off; it just can't cope with aggressive cornering right out of the box, when the entire contact patch or the greater part of it would be riding on virgin mold release.

I've been told of several methods for removing mold release that some riders have tried—wiping the tread with contact cleaner or acetone, or hand-sanding it with heavy-grit sandpaper. I've never tried any of them myself, so I can't verify their effectiveness or their impact on the rubber. But I have used the gradual-leaning method with every new tire I've had mounted and I've never experienced the slightest incident of tire slippage during those "break-in" sessions. □

Got a mechanical or technical problem and can't 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 949/631-0651; 3) e-mail it to [email protected]\ or 4) log onto www.cycleworld. com, click on the "Contact Us" button, select "CW Service" and enter your question. Don't write a 10-page essay, but if you're looking for help in solving a problem, do provide enough information to permit a reasonable diagnosis. Include your name if you submit the question electronically. And please understand that due to the enormous volume of inquiries we receive, we cannot guarantee a reply to every question.


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