Literbike Mods 2013 Suzuki GSX R1000
A highly adjustable K-Tech 35DDS Pro shock and separate springs came courtesy of Orient Express. Performance was nothing short of spectacular, especially when we adjusted the settings on the shock’s bypass valve.
Driven Racing D-Axis rearsets can be adjusted to fit just about any size of rider and were sturdy enough to be trusted on the track. Serrated pegs aren’t overly aggressive and should be rotated so that the edges bond well with your boot.
Core Moto SS brake lines in red colors were mounted front and rear. What? We like to be stylish, too.
Lightweight, EBC Vee-Rotors and track-day oriented EPFA Double-H pads improved brake performance up front, whereas FA pads ($38.74) and a rear Vee-Rotor ($145.16) were used out back.
The Bazzaz Z-Fi TC box is a user-adjustable traction control system that we’ve enjoyed playing with over the years. A nice feature is that it has an integrated quickshifter. Shop foreman Michael Candreia says that, “It all mounted up fine, it’s just time consuming to put it on.”
The 2013 GSX-R1000 project bike that graces these pages of the magazine is the byproduct of a single phone call. If you’ve ever crossed paths with longtime tuner Kaz Yoshima, who happened to be on the other end of that call, then you’d understand how so much could come from one conversation; Yoshima is a unique personality, with more ideas running through his head at any given time than most persons will spawn in their entire lifetime. This time Yoshima had a rear shock link that he’d developed while working for the very successful M4 Monster Energy Suzuki team in 2011, that he’d “love for us to try.”
We’re always looking for a chance to test the current crop of performance-enhancing modifications, so naturally we jumped at the opportunity to test the link. And then, in an attempt to take the build a step further, we outfitted the big-bore Suzuki with a long list of parts that’d be ideal for track-day enthusiasts and amateur roadracers alike. Enter SR’s 2013 GSX-R1000 Literbike Mods project.
The ultimate parts list
Yoshima’s link cost $480 at the time we went to press, is designed to be less progressive than the stock link, and is intended to have a different initial rate so that more of the shock’s travel can be used. Essentially, the unit reduces the load on the rear shock and allows you to use a softer spring out back, and because it is a direct replacement for the stock piece, mounting the link is extremely easy. On top of that, fit and finish is pretty impeccable. For more info on the intended use of rear shock links and how the Yoshima link works from an engineering point of view, refer to the sidebar below.
Our GSX-R was to be tested at first with the aftermarket link and a stock shock in an attempt to better understand how the link would affect handling, but we were also curious to see how the link would perform when paired to higherspec shock. K-Tech distributor Orient Express stepped in to help here and re-introduced us to its $1691.50 35DD S Pro shock absorber, which was developed by a number of top-tier racers and uses independent circuits for rebound and compression with 32 clicks of adjustment each. A bigger benefit, perhaps, is the shock’s hydraulic spring preload adjuster and bypass valve adjustment circuit, which allows you to fine-tune feel at the track. Tige Danne, longtime friend of SR and co-owner of CycleMall, handled installation duties and helped tune the shock while at the racetrack.
With our GSX-R now sporting a fresh pair of chassis upgrades, we turned our attention to the engine (the Yoshima link requires you remove the stock exhaust, although that’s a modification we would have likely made either way). A $1236 M4 Performance Exhaust full system with stainless tubing and carbon muffler was the first modification. Then came an $849.95 Z-Fi box courtesy of Bazzaz, a user-adjustable traction control system that uses RPM data to determine tire slip and ignition cuts to help the bike regain traction. We’ve experimented with Bazzaz traction control components on previous project bikes, and as was the case then, there were no snags in the install process. As our shop foreman, Michael Candreia, puts it, “It all mounted up fine, it’s just time consuming to put it on.” What’s nice about the Bazzaz Z-Fi TC is that it has an integrated quickshifter and is easily paired to the company’s $299.95 Z-AFM fuel mapping kit, which builds custom maps based on the data it gathers.
It’s worth noting that the Z-Fi TC has two maps which can be customized via Bazzaz software and adjusted via a switch that’s mounted to the clip-ons. Fortunately, Michael has mounted a few of the Bazzaz systems in the past and had no problem finding a home for the switch. Keep in mind, however, that an at-home installation will take some patience. The M4 exhaust went on with like ease and looks impressively built. Perhaps more impressive is that, when tweaked by Danne, our GSX-R1000 pumped out 169.8 horsepower, or around 13 more horsepower than a stock GSX-R.
In addition to the not-so-modest chassis and engine changes, we went ahead and installed a set of $529.97 Driven Racing D-Axis rearsets, which have nine different mounting positions from OEM height to 24mm back and 24mm up, an eccentric that’s available in multiple hues for added looks, folding levers, and adjustable footpegs that can be rotated to mount 12mm up, down, forward or backward. An $89.95 Competition Werkes Standard Fender Eliminator replaced the stock license plate mount, and the OE Bridgestone tires were jettisoned for a set of Pirelli Diablo Supercorsa SP V2 tires. Competition Werkes’ Fender Eliminator kit went on with enough ease that we’d say you could get it done without hassle in your garage, and the Driven rearsets were no more difficult to mount. They also provide plenty of adjustability for racetrack use and feel solid, with just enough of a serrated peg to keep your foot planted. Pay close attention to how you mount the pegs though, as we originally had them rotated to a position that put our boot off the serrated platform.
Brakes were the final focal point and were updated with the help of EBC, who provided a set of lightweight Vee-Rotors ($244.14 each) and EPFA Double-H pads ($75.00 each), which are intended primarily for street riding and the occasional track day and claimed to offer more bite and heat-cycling ability. Core Moto SS front and rear brake lines in custom red colors were added, mounted up nicely by way of maneuverable banjo fittings and cost $138.
Build complete, let’s ride!
To test our laundry list of GSX-R1000 modifications we headed to Spring Mountain Motorsports Park in Pahrump, NV , with TrackXperience, a Southern California-based track-day organization that promised plenty of track time over the course of a weekend. Convenient, especially considering we needed to test the bike in a multitude of configurations. Specifically, the test schedule went like this: stock link and stock shock, stock link with K-Tech shock, Yoshima link with stock shock and spacers (provided by Yoshima), K-Tech shock with 100 N/mm spring, and K-Tech shock with 85 N/mm spring. Whew, how we managed to get all that done in just two days we’re not sure!
After learning the track and asserting that all the hardware on our GSX-R1000 was tight, we paired the Yoshima link with the stock shock and were amazed to find that the link significantly concealed the stock shock’s downfalls. Grip was improved, plus there was a lot less movement from the rear at the entrance, through the middle and at the exit of each corner. Things only improved when we paired the K-Tech shock to the Yoshima link, as the combo provided even more composure at lean, although with the 100 N/mm spring we felt like we could use more feel through the middle of the corner. Sure enough, the softer spring solved that problem by giving us that extra sense of movement that we needed, all of which we were able to then control by adjusting the shock’s bypass valve settings. There really was no better setup than the K-Tech shock and Yoshima link, and any track-day rider or racer would be impressed with the setup’s ability to keep the GSX-R composed at track speeds.
In between suspension changes we experimented with the Bazzaz electronics, and even managed to build a few custom maps while at the track. That’s probably the biggest advantage of the Bazzaz setup: The fact that you can toy around with settings between sessions and learn how to fine-tune your setup without getting things too far out of the ballpark. Fueling adjustments really smoothed the throttle response over the course of the weekend, and the adjustable TC worked to keep us entertained as the tire went off. Would we have gone quicker without TC? Maybe, but this is a track-day bike after all, and that added safety net meant our chances of heading to the office on Monday in one piece were drastically increased.
The EBC brakes took a few sessions to bed in, but ultimately provided decent stopping power. Interestingly, the initial bite didn’t seem that aggressive, which leads us to believe that the manufacturer has tuned the pads/rotors to not overwhelm track-day riders. Surely, the company’s track-specific setup would be much more potent.
Pirelli’s new Diablo Supercorsa SP V2 tires got us through the two days of testing in amazing fashion and provided more grip than we could have ever expected from a street tire. The Supercorsa SP line of tires has always been good, but these are undoubtedly the best Pirelli street tires we’ve ever tested thanks to impressive warm-up characteristics and long-wearing compounds.
That’s a wrap
Our time with the GSX-R was short lived unfortunately, but in the end we were able to test multiple link/shock setups and a long list of capable, track-oriented modifications, which was our goal from the beginning.
Worth mentioning, of course, is that we installed all of the GSX-R’s parts in one fell swoop, essentially building a bitchin’ track bike all at once, but that the goal as a track-day enthusiast is to improve the bike over time or as money permits. If your wallet is deep enough, go ahead and build at will, as we have, but otherwise look at these modifications as stepping stones. Maybe this year it’s an exhaust that you can try, maybe next year it’s traction control, and the year after a shock. Hopefully, in the end, you’ll be as happy with your ride as we were with our GSX-R.
Most sportbikes are equipped with a linkage-type rear suspension system, which is used to translate the wheel’s travel into a desired amount — usually much less — of shock travel. These setups are generally based on a four-bar linkage mechanism, with the dimensions of the various bars determining the suspension’s characteristics. For example, on a sport-touring bike the linkage can be designed with a soft rate at the top of the stroke for a smooth and plush freeway ride, but further down in the stroke the rate is stiffer to better cope with heavy loads and a passenger — the link has a rising rate as it moves further into the shock’s stroke.
Even sportbikes have this same soft/stiff bias, but on a racetrack — where you rarely have big bumps or passengers — a more constant suspension action through the stroke is desired and this is accomplished with a link that has less of a rising rate. Kaz Yoshima’s link has this more linear action, as do most aftermarket links, but goes a step further with an overall rate drastically different from the stock link. This uses more of the shock’s travel, which gives the shock better control over the wheel’s movement and reduces cavitation.
By setting shock length and spring preload to specifically work with the link, Yoshima is able to make the stock Suzuki’s shock behave in a manner similar to an aftermarket race shock, with a noticeable improvement in performance. Matching the spring rate to the link — again, with the stock shock — provides another increase in performance, and using an aftermarket shock allows the full benefits of the link to be realized.
Bazzaz: www.bazzaz.net, (909) 597-8300
Competition Werkes: www.competitionwerkes.com, (800) 736-2114
CycleMall: www.cyclemall.net, (714) 258-7501
Driven: www.drivenracing.com, (866) 531-4836
EBC Brakes:www.ebcbrakes.com, (818) 362-5534
M4 Performance Exhaust: www.m4exhaust.com, (972) 481-9300
Orient Express (K-Tech shock): www.orientexpress.com, (800) 645-6521
Kaz Yoshima link: www.datamc.org/products, (406) 924-1717