The Processes of K-Tech Suspension Treatment
Story and pictures by Wahid Ooi Abdullah
If you thought being a motorcycle journalist is only about riding almost every single bike in the market, it’s only a blip about what we do. While it’s true we test the latest two-wheeled sensations, we had to unlock the bikes’ capabilities in a short time. The power is one thing, but we always held that a bike’s best trait is its handling. Hence the ones that we hold dear were the ones which handled the best, regardless of engine power and looks.
On the flip side of things, we also tested bikes which looked truly sexy and seemed to be powered by uranium rods, but handled like a slab of butter on a piece of hot toast. There was one had suspension was so hard it felt like our livers would pop out of mouths every time we hit a little bump, while their bigger brethren had the effect of liquefying our internal organs. It wasn’t a cruiser, but a naked sportbike so it came with fully adjustable suspension. No problem, just turn the dials here and there, right? Nope. No matter where we turned the knobs, the suspension stayed exactly the same or worse!
That was the worst case scenario, however, being complete bike nerds that we are, we’ve always thought about more personalized suspension settings.
Every bike sold to the public is compromised in some way, be it in terms of engine characteristics, ergonomics and the suspension. When a manufacturer produces a bike, it has to be accessible to a large proportion of the intended target audience. Even then, a large proportion of that target group may not agree with every characteristic of that bike. Thus a bike which enjoys great sales is the bike which could cater to the needs of the many.
But unlike in a car, every rider rides a bike differently and because of that, the chassis has to deal with a large cross-section of riding styles: Early, progressive braking; late, hard braking; trail braking; easy, progressive steering; hard, aggressive steering; early, progressive throttle; early, hard throttle; later, hard throttle while leaned over; hard throttle when more upright; less lean angle; elbow down lean angle; less mid-corner speeds; higher mid-corner speeds.
Compounding that complexity is our different physiology. Overall bodyweight is one thing, but how is it spread throughout the body? Bigger upper body? Wider hips? Bigger and heavier thighs and legs? Besides that, our physiology usually decides how we sit on a bike, resulting in different weight distribution around the bike: Bum all the way at the front or back of the seat or right in the middle? What about chest position in relation to the fuel tank? Fully upright or slightly bent or aggressively bent? How much weight does one hang off in a corner?
And what tyres do you use? The tyre pressure?
These aspects don’t only concern the likes of Rossi, Marquez et al, but also every rider in the pursuit of riding bliss.
So what can you do to personalize your suspension?
K-Tech Suspension are based in the United Kingdom and have enjoyed much success in the racing scene, including in the Isle of Man TT. Although an annual event, the TT course utilizes a section of the island’s public roads, instead of a closed, purpose-built racecourse. The Snaefell Mountain Course, as they call it is 60.725 km long and consists of more than 200 corners. The riders would race past houses, trees, utility posts, letter boxes, farms, towns over an undulating course, sometimes at speeds topping more than 320 km/h. Unforgiving and dangerous. Michael Dunlop has just posted the fastest outright lap during this year’s TT, at 16 minutes 53.929 seconds, averaging a mind-blowing 215.591 km/h.
K-Tech is involved with the top teams and riders including the multi-time Senior Class (Senior here refers to the top boys, not geriatrics) John McGuiness. It’s this data, accumulated from this punishing road course that translates to the development of better suspension systems not only for the closed courses but for the roads 99% of us ride on.
K-Tech Suspension Malaysia has enjoyed great success as well, partnering with Chia Motor PJ in their racing exploits in the Malaysian Superbike Championship (MSC). The team won the Group A Overall Championship in 2015 and came close to retaining that title in the just-concluded 2016 season.
Kratos Motorsports, the official distributor of K-Tech Suspension in Malaysia invited us for a firsthand look on the processes involved in upgrading the suspension of a 2014 Suzuki GSX-R 1000R at Chia Motor PJ recently. Proprietor Keith Chia is no stranger to the biking community, especially in racing. He raced in the AAM Malaysian Supermoto Championship last year and continues to ride motocross as well as on track days. So who better to perform the upgrades than him?
“K-Tech is a well-engineered product from the UK. The engineering team has great ideas on how to deliver the best suspension solutions to all aspects of riding, for both road and offroad applications,” said Keith.
Also present was Joachim Sebastian of Kratos Motorsports. You may remember his stunning Kawasaki Z800 in these very pages a few months back. “Word is starting to spread throughout Malaysia about K-Tech and we’ve had customers who came all the way from Kedah and the East Coast.”
Keith started by working on the rear shock as it’s a full replacement. The stock shock is mounted on a scale-like contraption which measures its overall length. The replacement K-Tech Razor R shock went on next, to check for the same length in its unadjusted position. Installing a same length item is important as to not “shock” the rider with a totally different chassis geometry (front and rear ride height attitude).
Installing the shock was straightforward, only requiring the rear brake’s fluid reservoir to be relocated. The Razor R is adjustable for preload (sag), compression, rebound damping and shock length. A separate adjustment for shock length is good, as the rider could set the necessary ride height without having to perturb the sag settings by adjusting the preload. The settings were left in their default K-Tech factory setup to allow the owner to acquaint himself to the “baseline” settings first. The owner’s feedback will be more accurate this way, should adjustments and fine-tuning are required at a later date.
The biggest portion of the manpower was spent on the forks, of course.
We’ll touch on how a motorcycle fork works in detail next time but one essentially contains (besides a spring) a piston which pushes down on the fork oil. The piston is equipped with passages that through them oil is pumped from the up-and-down suspension action. The resistance encountered by the oil as it’s forced through those passages turns kinetic energy into heat. The design of these passages determine the damping characteristics of the fork. (Think of compressing water in a can with holes of different sizes.) When you turn the damping adjusters on the fork, these passages range from being partially blocked to almost fully closed. The less oil (increased resistance) that flows through, the “harder” the fork feels, and vice-versa.
Advanced cartridge forks or cartridge upgrade kits like the K-Tech RDS that went into this bike’s forks, however, flow oil through a series of flexible shims that er… flex according to suspension speeds to provide damping. (Suspension speed means how fast the suspension travels up and down, unrelated to road speed.)
The Suzuki was fitted with Showa’s Big Piston Fork (BPF) as standard equipment. The BPF caused quite a stir when it was introduced. Again, without touching on specific details, the BPF uses the whole fork as the cartridge. The greater volume is purported to result in lower pressures, consequently, the oil travels at slower velocities. This in effect makes for good low-speed damping, as in limiting suspension dive during braking. With less suspension travel being dedicated to dive, more travel is available to soak up road surface irregularities.
But again, as good as the BPF is, it’s made for volume production. So relating back to our opening story, unless you’re Valentino Rossi, it’s not tailor-made to a single individual and may not be suited to your particular requisites.
To upgrade the forks, Keith first had to remove the internals of the Showas.
Once the top cap came off, we could see the central rod guide attached to it with the main piston (a large white-colored plastic) at the bottom. This allowed the top leg to be slipped off. The spring was then removed and the oil drained. The Showa’s fork bottom (at the base of the fork which incorporates the axle carrier and brake caliper mounts) is where you’d find the preload adjuster (a departure from the traditional position). It needed to come off as the RDS’s rebound adjuster will be fitted in its place.
The lower fork tube was screwed into the fork bottom and secured by Loctite. Keith heated up the section with a blowtorch to melt the Loctite. This is a delicate process but to which Keith is already accustomed to as overheating may damage the black powdercoat. Once the correct temperature was reached, Keith clamped the fork tube with a K-Tech special tool and turned it. With that out of the way, the remaining bits such as the preload adjusted shim was removed.
Time to reveal the K-Tech RDS cartridge kit.
It was immediately apparent that K-Tech uses more metal parts than stock. These high-quality parts were CNC-machined and treated in equally high-quality finishing. They ranged from being powdercoated, anodized, shot-peened or chromed. The main piston itself is made of metal. “The kit comes fully installed but I disassembled it to show you the internals. All the installer needs to do is follow the steps of reinstalling the fork’s internal parts,” said Keith. “K-Tech uses very high quality parts to ensure longevity and reliability. So that means your investment will last for a long, long time, when properly maintained.”
Keith also showed us the main spring, which was rated at 10.5 kg/cm. “You can’t go wrong. The spring rate is stamped on one end of the spring.” Besides that, he also showed us K-Tech’s proprietary fork oil seals – one internal and the other external. The internal seal holds the oil in.
Not all seals are equal. The 1993 Cagiva Mito I owned cracked its fork seals on the average of once every fortnight. It was finally resolved by using seals from a Japanese brand, replacing the stock Marzocchi items. As for the external seal, it functions as the barrier to keep dirt and other contaminants from entering the fork.
The top fork leg went back on with both seals in place. “It’s imperative that the internal surface of the seals are fully clean of impurities as dirt will score the fork slider leg and compromise the oil seals, resulting in a leak. In worst cases, the fork tube had to be replaced altogether. The tube isn’t exactly cheap!”
Keith first filled the fork with some SAE 30 grade oil and checked for leaks from the rebound adjuster. Satisfied, Keith slipped in the main spring next. He now allowed the assembly to sit for some moments to allow for air bubbles to come to the top and dissipate. Having extra air than the measured amount in the fork will compromise the characteristics of the fork, as it will cause cavitation in the oil, adding an unwanted variable in the fork’s action.
Keith came back from a break and installed the cartridge assembly. However, before capping it off, he pushed and pulled it up and down a few times, again to rid of the system of air bubbles and to ensure the oil had fully filled the cavities and orifices. Keith topped up the oil to the specified amount with a K-Tech special tool. The tool also measures the correct amount of air-space required.
A piece of yellow-coloured rubber washer was installed to the slider tube. “It’s to indicate the fork’s maximum compression. If the rider comes back with the washer way down, it could mean that we either need to increase the compression damping or maybe switch to a heavier spring. If the washer stayed up high, it would mean either there’s too much compression or the rider didn’t brake hard enough. That data will be corroborated with the rider’s feedback on his feel and we’ll adjust it from there,” said Keith.
“K-Tech systems need to be worked on with special tools,” said Keith. That is a positive because one can be confident that future maintenance can only be performed by a K-Tech specialist like Keith. “Our dealers need to also purchase the special tools.”
Finally, the fork was reinstalled on the bike.
Throughout the process, we couldn’t help but feel the dedication showed by Keith and K-Tech’s engineering. We also hope to gain the Suzuki owner’s opinion in the future.
In the meantime, do check out K-Tech Malaysia and Chia Motor PJ’s list of products and services.
KRATOS MOTORSPORTS and CHIA MOTOR PJ
No. 11, Jalan 21/17
46300 Petaling Jaya