Q In some of my internal-combustion engine design studies, I have come across the term "Con Rod Ratio." Although poorly explained in my textbooks, I believe it refers to the length of a connecting rod relative to the length of the stroke.

There are thousands of ways you can pledge your allegiance to Harley-Davidson and the V-twin for which it stands when you're not actually riding one. Tattoos. Decals. Doo-rags. Scary lingerie. But until the Newport News Shipbuilding Company introduces the USS Willie G. aircraft carrier, this is the top of the aspirational food chain. The spec sheet alone tells you that much. Topped off with 300 gallons of diesel fuel, the luxuriously appointed, two-door Class 8 tractor weighs in right at 22,000 pounds. Climb-and we do mean climb-into the cab and that expanse of hood covers your basic Navistar Maxforce 15: an inline, six-cylinder, intercooled turbo-diesel carrying 40 quarts of oil and 42 quarts of coolant. Though it won't fit on our dyno, International claims 550 horsepower at the 2000-rpm operational rev limit. Torque, however, is the story, as the strongest Maxforce six makes 1850 lb.-ft. of the stuff-roughly equivalent to the maximum output of 20 of the Motor Company's Twin-Cam 96 twins. We're talking about some serious twist here, with a bling factor to match.

Scattered clouds beget drops on your face shield, then a deluge of semi-Biblical proportions. Pavement that was dry and grippy 15 minutes ago is cheek-clenchingly shiny. What do you do? First, don't panic. To quote a Bene Gesserit incantation from Frank Herbert's Dune, "Fear is the mind-killer." Scared? Slow down. Find a bit of cover and pull over if you need to. Run through your options. Presented with enough rain to choke healthy adult toads, calculate the most direct route that puts a nice, dry roof over your head. Especially if whatever you're wearing isn't waterproof. Is your shield shedding water well enough? Is it fogging inside? You can't deal with what you can't see, so fix that first.

The big ZZR1200 arrived with a mildly bewildering split personality: part 145-horsepower cruise missile, part comfy long-haul sport-tourist. Was it a kinder, gentler ZX-12R or a slimmed-down Concours with anger-management issues? Both, actually, which is hardly a bad thing if you slow down long enough to think about it. After that, this one runs as fast as physics and the local constabulary will allow.

Honda CBR1000rr
Ringleader: Aaron Frank
Msrp (2008): $11,599
Miles: 4749-5899
Average Fuel Mileage: 43 Mpg
Accessories & Modifications: Taylormade Racing underbelly exhaust, rear hugger and fender eliminator

Tips, Tweaks, Fixes and Facts, plus Buyer's Guide and Expert Q&A from the Industry's Best

Q My new Triumph Bonneville has a serious problem. If the battery falls below 12.6 volts, the ECU will not let it start. With a fully charged battery, if I stop/start more than two or three times in the city, my bike will not start again. The only way to start it is to remove the left side cover and bridge the solenoid terminals. I have just fitted a new battery, but no change. The dealer from whom I purchased the bike is selling battery chargers with new bikes, so obviously Triumph is aware of the problem.

In the beginning, they taught you that braking and cornering don't mix. Get it done while you're perpendicular to the pavement. Now, after a few thousand miles of seat time, that same approach can get in your way. What if you need to fine-tune cornering speed after the bike is arced in and carving? Welcome to the fine art of trail braking.

Reinventing the Interceptor has always been risky business, mostly because every major makeover since the AMA Superbike Championship-winning 1986 VFR750F has moved it closer to sport-touring gentility. Some move more gracefully than others, but the heavily edited 2002 version is either a giant step forward or two in reverse, depending on your point of view. Blame the fifth-generation VFR800 that played to rave reviews from '98 to '01 for being such a hard act to follow. Trademark touches like four gear-driven cams made that 781cc V-four expensive to produce as well, so the VFR brain trust set off in a more civilized direction, complete with optional hard saddlebags.

Q I just finished re-reading your 2005 "Motorcycle Helmet Performance: Blowing the Lid Off" article and was wondering if there has since been any discussion between Snell and the various experts mentioned on more reasonable real-world tests and G-force allowances for head injuries. I am a first-time motorcycle buyer and value my life highly. I am currently in the market for a helmet and want to know if Snell has changed its standards or if there have been any major changes in motorcycle helmet manufacturing. I know it's only been four years, but you never know, right?
Donovan K Hamrick
San Rafael, CA

Train harder than you ever thought possible and you'll be prepared to meet the challenges of present and future battles. That is what a Marine Corps recruiter will tell you. Soldiers don't always fight a known enemy these days. But any Friday afternoon in commuter traffic is a battle, and you'd better be ready to engage.

In the beginning-familiar to most as 1998-Yamaha's cliche-shattering YZF-R1 changed everything. Then, after relatively major makeovers in 2000, '02 and '04, project leader Toyishi Nishida tossed most everything but the name in '07. Signature five-valve combustion chambers were replaced by a MotoGP-derived four-valve setup featuring titanium intake valves. A slipper clutch came from the limited-edition '06 YZF-R1 SP. The press kit coined new acronyms for MotoGP-derived electronics-most notably YCC-T fly-by-wire throttle and YCC-I variable-length intake runners. From larger ram-air inlets up front to oval mufflers and an LED taillight, precious few part numbers remained.

Tips, Tweaks, Fixes and Facts, Plus Buyer's Guide and Expert Q&A from the Industry's Best

Dear Angry Rider,
I am a lifelong motorcyclist, and have been riding on- and off-road for more than 30 years. As such, I make it a point to watch out for motorcyclists whenever I drive my car. But something you did today disturbed me...

Ask The Pro
I have had a problem with my 2005 Honda ST1300 since the middle of last winter. One day, I noticed that it did not warm up as quickly as it normally does. From there, things got interesting. After hundreds of miles of riding, I realized that the engine temperature was directly proportional to the outside air temperature. On a cold day, the coolant-temp gauge would never read more than one bar. On a really cold day, it would not show any bars at all. During the summer it seemed to be fine, going to three bars on the gauge and staying there. After investigating further, I think the thermostat is stuck in the open position. Two different Honda dealers have checked the bike, and neither could duplicate the problem. I know it hasn't gone away because of the extended time the bike spends warming up at fast idle, so I'm wasting fuel. It's still under warranty until September of 2009. Can you help?
Mike Bracken
Knoxville, TN

Triumph Bonneville SE
Ringleader: Damian Ercole
MSRP: $8399
Miles: 935-947
Average Fuel Mileage: I'll get back to you on that.
Accessories & Modifications: Looking forward to it...

A decade after its debut, BMW's 135-mph luxury suite remains the only viable foil to Honda's GL1800 Gold Wing. And like most other offerings from the Munich works, the KL1200LT approaches long-distance travel from an oblique angle. The last BMW K-four with its crankshaft parallel with the chassis rather than perpendicular to it, the 1171cc Flying Brick is essentially a 1996 K1200S engine tuned to favor torque over horsepower. Telelever front suspension and the familiar Paralever shaft-drive system out back add up to road manners that are more motorcycle than motor home. Factor in relatively generous cornering clearance and you can inhale twisty pavement in a hurry.

It was the one motorcycle John Bloor's resurrected Triumph Motorcycles Ltd. had to build, though they waited until 2001. Resemblances to the storied late-'60s Meriden Bonneville are purely intentional, if less than 100 percent faithful. The Hinckley version had to be reliable first and pledge allegiance to the past maybe third or fourth. It's bigger, and, at 499 pounds wet, almost 100 lbs. heavier than its forefathers. Starting with the DOHC eight-valve vertical-twin, every deviation from Edward Turner's original recipe helps deliver a better balance of nostalgia and practicality. Pistons rise and fall together in 86 x 68mm cylinders, spinning a 360-degree crankshaft with four main bearings. Dual balance shafts in the horizontally split crankcase allow solid engine mounts. Subtracting a cog from an existing six-speed gearbox and flipping the result put the clutch on the left, and the final-drive chain-along with the signature triangular engine cover-on the right.

Because you wanted a new one anyway, right?Sick of your bike? Sick enough to gift-wrap it for the local felons? Imagine the money they'll make. According to our friends at the Chula Vista, California, Police Department, an ambitious thief can pull down six figures per year nicking bikes just like yours. On second thought, save the gift wrap: Here's how to earn a spot on your local grand larcenist's Christmas-card list.

Q I just traded a Harley and an old snow-blower for a really clean '07 KTM 950 Super Enduro R. Aside from a bit too much bark out of the Akrapovic cans that came with it, the bike is essentially perfect for me: comfortable, well-behaved in the rough stuff and very fast. I'm still getting used to that part. My question is, since I'm heading out on more aggressive rides farther from home, what should I do to help the bike survive a tip-over in the middle of nowhere? Also, I've added a couple of things to the stock tools--tire levers and tubes, for example--but do you guys have a don't-leave-home-without-it list? How would you carry it: Butt bag? Tail pack? Both? I usually ride with a buddy or two, and we're not training for the Dakar Rally. I'd just like to feel like I'm carrying the right tools and spares.
Kai Lennart
Tucson, AZ

Kawasaki ZX-6R
Ringleader: Ari Henning
MSRP (2009): $9799
Miles: 226-1089
Average Fuel Mileage: 34 mpg
Accessories & Modifications: Tech Spec Gripster pads

Braking from a fast straightaway into a slow corner can peg anyone's pucker meter, but it's a calmer and safer operation when you scrub off most of that velocity sooner rather than later. Let's say you need to get from 80 mph to 30 just in time for a cute, decreasing-radius left. Relax. Squeeze the bike between your knees to minimize the amount of upper-body weight supported by your arms and hands, and to keep from sliding forward suddenly. Keep your weight relatively low and centered on the bike. Simultaneously roll off the throttle and squeeze the front brake lever--think smooth and firm at first--as you feel the weight shift forward to compress the front suspension and load the front tire's contact patch.

Q I just bought a 2009 Honda CBR1000RR and I'm looking to modify the exhaust. I'd like to install a slip-on rather than a full system, but after reviewing the available slip-ons, almost all of their mid-pipes make an S-bend before reaching the end cap. The only system that doesn't is from Two Brothers. I'm no scientist, but wouldn't a freer-flowing straight pipe improve horsepower over a pipe that make several turns?
Pepe Martinez
Royal Palm Beach, FL

Forget about the nasty red oxides that can show up after a motorcycle's long winter nap. There's a more insidious sort of corrosion: the kind that builds up between your ears when it's too cold and wet to ride, eating away at your confidence and slowing you down-or worse. You feel it the first few times Old Faithful rolls out of the garage under bright sun and blue sky. Mr. Sphincter tensing up at next to nothing? Trucks look bigger? Things happen a bit faster than they did last fall? Relax. Slow down. Caught in the early stages, it's nothing to worry about. Mental rust comes off quickly if you're willing to work at it.

Impressionable types outside BMW's cult of personality were not impressed with the first K1200S in 2005. After all, it's only good for 168 mph at the top of sixth gear-a virtual doorstop next to Suzuki's 186-mph Hayabusa. Meanwhile, the BMW's 150 rear-wheel horsepower are quite sufficient to dilate more discerning eyes with 10.3-second quarter-mile runs at 137.5 mph. This just in: Zero to 60 in 3 seconds flat is quick. Period.