Part the Third, in which our hero dabbles in the black art of suspension.
As you may or may not have read in parts one and two of this series, the 1999-2009 Suzuki SV650 and SV650S is a dependable, affordable, good-handling, light and very fun motorcycle that appeals to commuters, racers and track-day junkies, but it’s not that great out of the box. And of all its flaws, perhaps the hardest to tolerate without modification is the suspension.
Here’s the thing about suspension. No other modification gives you more riding pleasure when done properly, but doing it properly is much easier said than done. It’s not easy to understand how suspension works and how to best improve it. Want more power or better throttle response? Easily done with intake and exhaust modifications (which may not actually make you faster, but it will be louder, which seems to be good enough for most riders). Better braking? Steel-braided lines, master-cylinder rebuild, new pads will yield massive improvement in most cases. But suspension? I talk to a lot of riders, some with many years of riding experience, who have a fuzzy understanding (at best) of what all those valves, tubes, springs and oil do.
I am one of those people. Believe me, I’ve talked to many suspension gurus over the years, including the brilliant Jim Lindemann (ride in peace, Jim!) and equally brilliant Paul Thede, and even though I can (sort of) adjust suspension and (sort of) understand what those guys say, when I try to talk suspension with laymen, I realize how little I truly understand.
Luckily, you don’t have to learn from me. If you really want to understand suspension, get a copy of Paul Thede’s Motorcycle Suspension Bible and wallow in the 256 pages of very readable text (co-written by Total Control author Lee Parks) and 534 photos and illustrations (by talented illustrator and graphic designer, and occasional MD contributor, Alan Lapp). Another cool source of suspension knowledge is this iPhone app that contains all kinds of suspension-related videos, podcasts, blog posts and other material from Dave Moss Tuning.
You may not be a book learner, though, so I’ll share with you a brief summary of what I’ve learned in the last 20 years of sport-riding, racing and moto-journalism when it comes to improving your stock front suspension.
1) Damper Rods Suck.
Back in 1934, when the Nimbus appeared with the first hydraulically damped fork, it was a big deal. Eighty years later? Not so much. Here’s my understanding of how they work, which will, no doubt, be corrected in endless (if boring) detail by our enthusiastic readers below.
With a damper-rod design, oil squirts through tiny holes in a tube, controlling how fast the fork compresses and returns to its original length (also called “rebound”). There are different kinds of suspension action: “low-speed” refers to smaller bumps and irregularities that cause the fork to move slowly, and there are “high-speed” (also known as ‘oh, crap!’) bumps that make the fork move faster. The problem is that with a damper-rod, high-speed or low-speed compression and rebound have to be the same, since they use the same holes. As you may have guessed (or noticed), what’s good for the high-speed goose isn’t always best for the low-speed gander, and vice versa, which means you have to find a compromise between too harsh and too soft, which, like many compromises, means both actions are far less than ideal. For a better, and more detailed explanation, read this excerpt from Motorcycle Suspension Bible on the Racetech website. Do not feel guilty if you have an urge to do laundry after reading three paragraphs.
I tried to find a balance with the stock SV dampers. I asked well-known moto-tuner Dale “Holeshot” Walker what he recommended for those looking for an ideal springs-and-oil upgrade. He sells the Progressive Suspension fork springs kit, which includes progressively wound springs and a couple of pieces of PVC tubing for spacers. Progressive tells us its springs reduce front-end dive by being progressively wound, which means the springs get stiffer the more they compress. Interestingly, Progressive’s spec sheet shows their spring’s initial rate at .71 kg/mm—just a hair stiffer than the stock .706 kg/mm springs. Dale recommended I use thicker oil as well: 10-weight, much heavier than the 5-weight Suzuki recommends (if you’re not bored enough by suspension arcana, check this out: there is no standardization of suspension fluid weight, so one brand’s 5-weight may be closer to another brand’s 10-weight, which is why you may want to use branded fluid for your specific suspension products).
The spring swap is easy to do: pull your forks off, pour the oil out after removing the top caps (here’s a concept for you, Suzuki: drain plug) and set the new oil to the recommended level (pro tip—do this at your workbench, with the springs out and forks compressed so you can easily shine a light down there and measure the level). Note the Progressive springs are longer and take up more volume, so you have to use a lower oil level than stock). Drop in the new springs, calculate your spacer length, bolt on the caps and then put your front end back together. This would be a good time to bolt on some preload-adjustable fork caps if your SV (or other damper-rod equipped bike) doesn’t have them. You can buy the Suzuki parts or try an aftermarket vendor: they should be under $100 either way.
I’m not sure the new springs were worth the effort. I did notice less dive while braking, but damping was not much improved, with the bike’s front end bouncing about as we traveled over bumpy California freeways. Not the springs’ fault. I tried heavier 15W oil, which made rebound slower and compression harsher and did only a little to alleviate the bouncing and vague feel from the front. It was clear I wasn’t getting off cheap.
No worries—my 2000 is actually my second SV, so I knew the magic word: emulators.
2) Cartridge-Fork Emulators make you go faster for cheap.
If I told you there was a little gadget that would make your front suspension work as well as really good stock suspension for $170 you would want it. Racetech makes such a doo-dad, called the Gold Valve Cartridge Emulator. Paul Thede says he invented it in the early ’90s to “provide the compression damping curve of a cartridge fork, make it tunable, and offer it at a very reasonable cost.”
Emulators look like a dreidel that sits atop your damper rod, under your fork spring. There’s a lot of jargon involved in explaining how it works, but it basically substitutes for the function of the stock damper rods (the installation process requires you take out those crappy things and drill out their orifices) and through some clever but simple check valves and other tricks, emulates (hence the name) the action of a cartridge fork’s shim stack.
Clearly, there are disadvantages. First, you have to drill out and modify your damper rods to install emulators. Next, even though they offer some adjustment, you have to pull out your springs and fish out the emulators to turn the adjuster screws. Finally, if you know less about suspension than I do, you need to have a professional shop install them, unless you’re a hardcore do-it-yourself-er and love trial-and-error.
Racetech will do the install for about $125 on top of the cost of the parts (you’ll want to use Racetech’s recommended springs), but I called up James Siddall at Super Plush Suspension in San Francisco to do a fork service as well as an emulator installation. James has a very long history of off-road and roadracing suspension tuning, and one of the techs, Matt, has a long history of racing and riding SV650s. He calculated the spring rate, preload, oil weight and emulator setup I’d need and bolted it all together. Time to see if the emulators were as good as I remember.
3) Swapping out for fancy GSX-R forks may not be worth the trouble and expense
Back in 2002, before I sold my first SV, the common wisdom was to install emulators, not just for street and trackday riders, but racers as well. In fact, Thede claims an emulator-equipped SV and cartridge-fork equipped SV were on the same WERA endurance race team (ridden by Total Control author Lee Parks) in 2001, taking a national title while posting identical lap times. Eleven years along, things have changed, with the zeitgeist favoring swapping out the entire front end for a late-model GSX-R setup. So what’s better?
I’m going to ride my bike back-to-back with a GSX-R-equipped example and see which I prefer, but I’m here to tell you that I did a trackday on my bike recently and found the emulators still do exactly what Thede promises. The ride is plush, controlled and there is no wallow or vague feel from the front end. I think it needs a bit more dialing in, but the front is much more confidence-inspiring, keeping the front tire firmly on the ground. I maintained a brisk B-group pace, passing many riders regardless of what they were on, without feeling like I was outriding my suspension. For street riding, it’s great, allowing me to ride faster and more confidently on bumpy pavement.
I’ve seen sites discount the springs and emulators to $262 as a package (another interesting option is to purchase Traxxion Dynamic’s “Drop-in” kit that includes new damper rods in addition to the emulators and recommended springs for $350, making it easier to do the swap yourself and preserving your original equipment if you want to return to stock). That means you’ll spend about $450 to do this upgrade (with shop help), about half of what a GSX-R swap would cost. Of course, the GSX-R swap gets you modern four (or six)-piston calipers and giant discs…but you also have to contend with subtle changes in steering geometry as well as a need to customize your instruments, headlight and handlebars. I’m here to tell you there’s an option, thanks to Racetech—stay tuned to see if it’s the best one.
Next: Rear Suspension.
Gabe Ets-Hokin is the Editor of City Bike magazine, and a frequent freelance contributor to MotorcycleDaily.com