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Paul Dean
Get Shorty-a bike
I own a 1997 Yamaha YZF600, and my wife loves riding on it with me everywhere I go. She wants to ride on her own, but she’s only 4-foot-10 and finds that even a bike like the Kawasaki Ninja 250 is too tall for her. The closest things I’ve been able to find that might fit her are an Aprilia RS50 and a Yamaha YSR50. She doesn’t want a cruiser but does want to be able to do at least 100 mph. I was thinking of lowering the YZF for her. Should I? What are my other options?
Josue Galvez Ft. Irwin, California
You and your petite wife are impaled on the horns of a genuine dilemma. By stipulating that she has no desire for a cruiser but does require a bike capable of running at least 100 mph, your wife has eliminated virtually all applicable possibilities.
Take your Yamaha, for example: Its seat height, 31.7 inches, is too tall for her, but so is the Ninja 250’s at 29.3 inches. You would, therefore, have to lower your YZF 2/6 inches just to equal the Ninja in seat height, then drop it another inch or two so your wife could plant her feet firmly on the ground. But by that point, the YZF would have very little remaining suspension travel and ground clearance. As a consequence, the ride would be brutal and the bike couldn’t be ridden safely because its ability to lean into a turn would have been severely impaired. Bad idea.
You could buy the 250 Ninja and “slam ” it an inch or two, but you d still end up with a bike that won 't quite reach 100 mph (93-94 with a tailwind) and has limited cornering clearance— although not as much so as a lowered YZF600. Buell’s new 500cc Blast is another logical candidate, especially with its optional 251/2-inch-high seat, except that it, too, is only a 90-plusmph motorcycle. If your wife is willing to be somewhat lenient in her definition of a cruiser, she might consider a Harley-Davidson Sportster 883 Hugger. It has a 27.1-inch seat height and, with minor exhaust and intake modifications, is fully capable of 100 mph.
It would seem, then, that your wife will have to compromise somewhere, either in her top-speed requirements or her disdain for cruisers. Because with the current crop of available motorcycles, no one bike meets her criteria.
What’s up with EXUP?
I have a couple of questions regarding my 1998 Yamaha FZR600. 1 recently installed a Vance & Hines SS2-R slip-on silencer and it sounds great. I went with a slip-on instead of an entire exhaust because I was told that the header section would screw up my bike due to the EXUP system. Is this true? And what about jetting? With the slip-on and the stock header, should I use a Stage 3 Dynojet kit or would I be better off with just a Stage 1? Any help would be appreciated.
Brian K. Broyles Elmendorf, Alaska
I wouldn’t quite say that use of an aftermarket header would “screw up ’’ your FZR, but the engine would probably suffer a slight power loss somewhere in the rpm range because of the elimination of the EXUP system. EXUP (Exhaust Ultimate Powervalve) is Yamaha ’s method of using a movable valve in the header to change the tuning characteristics of the exhaust system according to rpm. At lower engine speeds, the volume of the system is tuned for optimum power output in that range of rpm: as the engine revs up, an electronically controlled, rpm-sensitive valve in the header closes, which reduces overall exhaust-system volume to enhance the power output at higher engine speeds. If you do away with the EXUP system by installing an aftermarket header, the engine may gain power in one range (usually at higher rpm) while losing a little in another (most likely the midrange), because the new' header must make do with only one, non-adjustable volume.
As far as jetting is concerned, the Stage 1 Dynojet kit should be all that your FZR600 needs. The Stage 2 and 3 kits are intended for more heavily modified and racing engines, whereas the Stage 1 kits are designed for near-stock applications.
From debt to doubt
Recently, a neighbor paid off a debt he owed me by giving me a 1995 Honda CBR600 that had been sitting in an unheated garage for about a year and a half. Aside from some minor corrosion, the bike is in pretty good shape except that it won’t run. The electric starter spins the engine just fine, and it seems to have good compression. I don’t have a compression gauge, but if if I turn the engine over with all of the sparkplugs removed, I can feel a strong blast of air exiting all of the open plug holes as the pistons come up through their compression stroke. There’s a healthy-looking spark at all of the plugs, and there is fuel in all of the float bowls. So, why won’t it run? When I removed the air-cleaner element and tried squirting a little bit of raw fuel into the carbs through the airbox, the engine attempted to run for a second but then died and refused to even sputter. Got any suggestions?
Don McMichael Troy, New York
Most likely, the jets are clogged, preventing the fuel in the float bowls from being drawn up into the carb throats. The engine ran momentarily when you squirted fuel into the airbox, indicating that the other ingredients needed to produce combustion were present in sufficient quantities and occurred at the proper time. All they needed was the introduction of fuel, which your carburetors apparently cannot provide.
Jets frequently get clogged when a bike sits unused for a long time without any stabilizing additive in the fuel. The volatile ingredients of gasoline eventually evaporate, leaving behind a hard residue called varnish. When the fuel in the float bowls evaporates, the varnish tends to plug any jet that had been submerged in the fuel.
If this is the problem with your CBR, you can remedy it by removing the jets and soaking them in carburetor cleaner. Once all the varnish is dissolved, blow high-pressure air through each jet’s orifice to remove any remaining deposits before reinstallation. And if for any reason, cleaning the jets is not an option, simply replace them.
Sport-touring heavyweight
I am 6-foot-2 and weigh 240 pounds, and I just purchased a 1994 Kawasaki ZX-11. The bike is awesome! I usually ride a cruiser and never knew that sportbikes could be so much fun. My question is, where can I get a kit or all the necessary aftermarket parts to lower the footpegs, raise the handlebars 2 or 3 inches and raise the windscreen slightly? I want to try to convert the bike into a sport-tourer. Is such a thing possible, or is this just an old man’s dream?
Vulkan96 Posted on America Online
It’s very possible. You could start by reading our August, 1993, issue, which
contained a story about a project ZX-11 (“ZX-11 for the Long Haul’’) we modified for sport-touring duty. That bike was fitted with a host of aftermarket components, many of them intended to address the same issues that you have identified. Although nearly seven years have passed since that story appeared, most of its information remains valid.
One exception is that the 2-inch-higher Heli handlebars we used are no longer available; the good news is that their manufacturer, Heli-Modified (800/8594642), now sells what it calls Multi-Tour Sport Bars to fit the ZX-11. These $385 bars are adjustable in several planes, offering a range of possible handgrip locations and angles to suit a wide variety of riders. Zero Gravity (818/597-9791)
still markets taller windscreens for the ZX-11, in clear for $70, and in light or dark smoke tint for $80. We don’t know of any company that is making lower footpegs for the big Kawasaki, but Corbin-Pacific (800/538-7035) has slightly higher seats available that provide the same effect as lowering the pegs. Raising the seat does effectively make the handlebars lower, of course, but the adjustability of the Heli bars should allow you to compensate for the added seat height.
Getting the shaft
I recently read a motorcycling newsletter that had a page-long article on the care and maintenance of belt final drives. That made me think about a HarleyDavidson I had years ago and the problems its chain drive caused me. Back then, I had more time to tinker and less knowledge of final drives. Now that I am older, I have less time to tinker but am more experienced, and I like the shaftdrive idea better. Why would you want to check continuously for alignment and guess at the proper tension adjustment when all you have to do with a shaft drive is change the oil and forget it? The lack of shaft drive is the main reason I do not own an American motorcycle today. I think it’s time for the American motorcycle manufacturers to break away from lawnmower engineering and start using today’s shaft-drive technology.
Darrell Peters Minden, Iowa
Your “lawnmower engineering’’ assessment might have been valid 25 years ago, but it no longer holds up today. Belt and chain final drives have come a long way in recent times and, compared with shaft drive, have proven advantageous in many applications.
And make no mistake, shaft drive has disadvantages. For one, it is much heavier, which increases unsprung weight, making more difficult the task of attaining a good ride. Shaft drive also tends to have adverse effects on chassis dynamics unless the swingarm is exceptionally long (impossible with most existing engine designs) or configured like BMW’s Paralever system (which no other mainstream manufacturer currently offers). Further, shaft drive is more expensive
to manufacture, more difficult and expensive to repair, causes greater frictional power losses and makes gearing changes either highly impractical, prohibitively expensive or downright impossible.
Meanwhile, belt and chain final drives are much better-suited for racebikes, sportbikes and most other high-performance applications. What ’s more, with all the customizing performed on Harley-Davidsons, belts and chains permit easier, less restrictive modification of the swingarm while allowing the bike to retain the classic style that is so highly revered. As far as reliability and maintenance are concerned, H-D final-drive belts have a remarkably low failure rate, even when subjected to nearly twice the power output of a Stocker. On unmodified Harleys, they frequently last as long as 100,000 miles with only one or two adjustments. In fact, the designers of the new belt-drive Buell Blast were so confident in the belt’s resistance to stretching that they provided no rear-wheel adjustments whatsoever.
For love or money?
I have a 1984 Kawasaki 900 Ninja that was my first bike, so it holds some sentimental value for me. Just recently, it broke a connecting rod, poking a pretty big hole in the crankcase. I’m wondering if it would be worthwhile to restore the bike or should I just scrap it? I’ve already bought several new components for it (tires, rotors, brake pads) and know that I won’t be able to get my money back for them. If I decide to invest in a restoration, I would try to bring the Ninja back to its original glory. Should I go ahead with this project?
SPYSTANG Posted on America Online
Only you can answer that question, because only you know how much sentimental value the bike holds for you. But from a financial standpoint, restoring a 1984 Ninja 900 with a blown engine is not a sound proposition.
If the bike were in excellent condition, both mechanically and cosmetically, its current street value would only be somewhere around $2000. It’s a marginally collectible bike, and there s no reason to believe that its value will escalate significantly in the future. If the engine damage is as extensive as it usually is when connecting rods break and flail around, the repair will involve a lot more than just a new set of cases and one rod. You easily could invest more than $2000 just in getting the engine repaired, and you’d still have to deal with the expense of restoring the rest of the bike. Unless you can get all of the necessary parts at a significant discount and do all the work yourself you will never even come close to recouping your investment.
