When times are hard, manufacturers know they must keep interest high even if they can’t do the same for sales. But new products cost money—money for engineering, for testing, for new tooling. That money just doesn’t exist! Where is the new pizzazz to come from?
Help is at hand from two well-proven techniques. One is to punch up tired, existing models with Bold New Graphics! Skeptics call this “shelf-paper engineering.” The other is to punch ’em out: boost displacement by either boring or stroking existing engines.
Kawasaki has two of these punch-’em-out models: a 296cc version of its well-liked 250 Ninja Twin (admittedly more than just a stroker crank, considering its new frame, bodywork and more), and a 636cc version of the successful four-cylinder middleweight sportbike, the ZX-6R. Both bikes have in their time been considered “entry-level,” so these low-cost makeovers work to keep the sales doors open. Want fuel economy and style? The little Twin fills that bill. Want to step up? The 636 is not your big brother’s “little” 600.
Older riders remember an earlier round of this same game. How do you suppose the “600 class” became established as a category? In the 1970s, 500cc was a middleweight, so it made sense to reach for more market share by nudging that up to a 550. Hey, that’s a step up from 500. Here’s my money. You play to success, so 550s were soon pumped up to 600s. Yamaha’s two-valve Seca led to Honda’s four-valve CBR600, and soon, everybody was doin’ it. The race to stuff “basic” 600s with more and more big-bike features was on. The pump-up was institutionalized as AMA racing’s 600 Supersport class of the 1990s.
Riders who are even older remember the British invasion. It started pre-WWII with a few 500s, but once the war ended, Americans couldn’t get enough of these lighter, more-agile 500cc Triumph, BSA and Norton Twins. And they wanted more and more performance. No problem! Boring bars were adjusted, and 500s became 600s, then 650s and even Enfield’s 700.
England’s two-wheel industry was not “R&D-oriented,” so this boring-bar engineering suited cheese-paring stockholders just fine. When the big, heavy pistons in Norton’s 850 shook test riders’ fillings out, engineers came up with Isolastic engine mounting to separate the rider from the pounding. Yes, you’ve guessed it: Engines originally designed as 500s began to show durability problems—wallowed-out main bearings and gears with missing teeth—when displacement was pumped up by 50 to 70 percent. They’d pushed a simple idea too far.
Japanese manufacturers aren’t making those mistakes because their testing departments employ proven procedures. And the boring bar of the earlier era has become the stroker crank of today.
Why? Today’s new-technology, lightweight four-strokes have no extra metal in them for overboring. So, with a minimum of fuss, new stroker cranks are coming down the line. We have a new model easy-peasy.