Track Bike Builder part 1: The weighting game

How was your weekend? Fattening? I think we’re all in the same boat, but I’m not too worried. Most of the mail that comes through my door is suggestive of some form of fat camp, or special slimming drink that’ll burn off your man-boobs while you watch Corrie. Of course, not everyone wants to lose weight, but when it comes to riding bikes, there are quite a few benefits to slimming down. For starters, you might find yourself fit enough to tick off a whole session of a trackday. And then there’s the physics of the matter; the heavier you are, the more your motor will struggle. Losing weight is an essential ingredient when looking to up your performance and it’s as dependent on your mass as it is your bike’s. You’re in it together, and considering most modern litre sportsbikes weigh around the 200kg mark, you’re looking at around 300kg per rider and motorcycle by the time you’ve got your leathers on and you’ve scoffed that extra donut to keep your sugar levels up. That’s a lot of weight to haul around, regardless of what bike you’ve got, so it makes sense to try and shed as much of it as you can. Take this stock Gixer, for example, which weighed in at 202kg on the scales and kicked out a genuine 186bhp on the dyno. That’s no bad starting place, with a power-to-weight ratio of 0.92bhp-per-kilo. But that’s a figure that could get better. Of course, by upping the engine’s performance we could find extra poke and improve the ratio, but that’s not going to help us in the handling department, or improve the bike’s stop-ability. So a strict diet is the answer, and in order to get this standard machine a little more trim and ready for the track, we asked Hawk Racing to get stuck in.

No one knows the latest iteration Suzuki like the Buildbase-backed BSB team. For three years now they’ve championed the model, achieving BSB wins, superstock wins and, probably even more impressively, a senior TT win just months after it arrived on the market. Rolling this road-clad street bike into their Mallory Park set-up didn’t even make them blink – it was business as usual. It goes against the grain to dismantle a perfect functioning, aesthetically impeccable, six-month-old motorcycle with just 2000km on the clock, but that’s exactly what we were doing, under the guidance of the team’s superstar racer and top technician, Leon Jeacock (he asked me to write that). Within seconds of the bike finding a home on one of the workshop benches, the orders were flowing, with the first task being to remove the stock fairings and panels. Like one of those geeks that complete Rubik’s cubes while reciting the alphabet backwards, Leon had the bike stripped to its bare bones in no time, revealing the skeleton and components that made up the core.

‘Never see the road again’

There was a lot under the skin and a lot to get rid of but by this point, with the bodywork gone, the GSX-R was already 9.6kg lighter. This bike will never see the road again, unless some tea-leaf takes it for a joyride, with the plan being to use it on trackdays and for racing. That meant we had no need for a number of units, like the AIS (Air Injection System) that, in conjunction with the purge valve pump, dampens the harshness of the emissions. We binned them both off, shedding another 800grams from the mix, but for every bit removed, there was often a price to pay. You don’t go to the dentist to have a bad tooth drilled and leave without a filling, and this case was no different. Blanks and plug-ins were the order of the day, with Performance Parts’ array of Yoshimura trick bits coming to the rescue. Purge line eliminators were added on-board, while the AIS system needed a Second Air Blind Set to stop debris or air from entering the cam cover. The side stand was another victim of our onslaught, and that too needed a Yoshi plug-in to stop the ECU from having a melt-down.

Another electronically governed heavyweight that we definitely didn’t want was the chunky ABS unit, sat smack at the back of the frame. You can just keep the unit mounted and use a Yoshi module to disconnect its function, but I didn’t see sense in lugging the extra mass around. Unloved and unwanted, it was time to get the snips out and cut the stock brake line that fed fluid through its chambers. With its waste liquid collected, the unit was removed in a jiffy to the tune of a 1.2kg saving. It was one hell of a lump that, when removed, helped to give the strip-down some legs. The BSB superstock regs state a minimum weight of 174kg. At the start of the day that figure seemed a little bit of a stretch to reach, but we were already well underway and the best was yet to come.

Exhausting work…

If you’re wanting to slim down your stock road bike’s mass, there’s one component that will have a bigger hit than anything else; an aftermarket exhaust. Forced to meet the rigours of emissions and noise standards, bike manufacturers have had to introduce extensive measures to strangle sound and limit the amounts of nasty gasses mullering the atmosphere. But it all comes at a price, and it’s a heavy one at that. A typical steel system, like the one on this Suzuki GSX-R1000 usually comes with a host of debilitating features, like a catalytic converter (which weighs a good chunk), a noise regulating valve (that adds even more weight) and a big old hefty muffler (that can be used as a weapon if someone breaks into your house). It was one for the scrap heap, but getting to it took a bit of time. If you’re in a hurry, you can just loosen the radiator brackets and force the item out of the way, to gain access to the manifold studs… but Hawk don’t do things by halves. Plus, it made sense to take the rad off completely as we needed to drain it of its anti-freeze in readiness for track use. It wasn’t too much of a biggy, requiring a quick drain down and the removal of a few hoses and clips. It also gave us access to the bike’s twin fans, which we chose to unplug and remove for more savings.

Spinning spanners like a pro Leon had soon got the boss of the standard system, which weighed a ton and looked as pretty as Mike after (another) late night punch up. That’s not meant to be a dig at Suzuki; it’s the reality of today’s standard systems. It weighed in at a whopping 11.4kg and begged to be replaced by a sleeker, shinier alternative. Based on budget, quality and function, you’d struggle to do better than a Yoshimura stainless race system, with an R11 end can. That’s what the Hawk boys run on their stockers, and it was also the substitute I’d got lined up. Devoid of any do-gooder gadgetry, the sumptuously crafted pipework hit home at just 6.6 kilos – saving almost 5kg over stock. Unlike a road system, the pipework is split into four separate headers, a four-way collector, link-pipe and the can. Leon was in his element bolting this bad boy together, starting at the headers and building his way backwards. I took it all in from a distance, keeping my hands clean while his blisters began to burst. As well as the low weight being surprising, the other thing that hit me was the lack of gaskets – it just slid into itself and got pulled into place by a multitude of springs. It took a matter of minutes to get the thing mounted and while I brewed up for the ninth time that day, Leon nipped into the stores to show me the ultimate race system. It was the type used on their superbikes, a Yoshimura Alpha T, made of pure titanium and weighing in at just 3.5kg. It looked a treat and felt as light as your wallet would be after buying one. At more than `2.4 lakh a pop, these are not for the faint-hearted, but there is no other way of saving 8kgs in one foul swoop, short of riding naked. With the credit card already rammed, that kind of spending proved a bridge too far. Besides, I was more than happy with the stainless option, and content that the light Yoshi exhaust hangar had saved even more precious grams over the pillion footpeg mount that’d done the job previously. With the new exhaust in place the radiator needed to be refitted, but not until I’d added an Evotech Performance guard to its face. Doing this job, burst radiators are not uncommon and they’re a bloody nightmare problem, let alone dangerous. The stock Suzuki comes with an oil cooler guard, but the unshielded rad is just asking for trouble. Despite its young age and low mileage, this GSX-R’s unit already looked more battered than a piece of cod, so it was something of a relief to get the new guard fitted to it; simply clipping into place up top and securing with bolts at the bottom, to the oil cooler framework. On the one hand it seemed counterproductive to be adding weight when we were hell-bent on losing it but, as my mother always told me, you should always wear protection. The superbike boys run guards on their bikes, and shield their engines with GB Racing’s brilliant engine covers… so I followed suit. All in, the four GB covers, a shark’s fin and a pair of crash bobbins cost an additional kilo in mass, but it was easily written off with the fitment of a Shido lightweight battery. The original had clocked in at 3.1kg, whereas its 600 gram Lithium Ion replacement felt so light I wondered if it was hollow inside.

We were still on track for our 174kg target, and Hel braided brake lines only aided our cause. We’d saved a metre of hose already, by not needing a length to reach the ABS pump, but the featherweight, super-strong braided racing lines from Hel not only upped the bike’s stopping credentials, but actually chipped 100 grams off the block. That was a pleasant surprise, just like the Bonamici aluminium filler cap (108grams), that replaced the lardy, key operated stock item (386 grams). Throughout the build of the bike Leon would let out nuggets of reason to where we were trying to save weight and why, reassuring me that he didn’t just have a fetish for unbolting bits. The main goals were to lose weight overall, but to also centralise the bike’s weight and keep it as low as possible. The lower the Centre of Gravity, and the more central the mass, the more stable the bike would be and the easier it would turn.

Un-sprung goodness

Another big hitter in the handling department would be to lose as much un-sprung weight as possible. There were a number of different ways to do so, with most obvious being to exchange the stock steel sprockets for lightweight aluminium options. This fix alone saved over 400 grams, and a race-spec RK chain, with ultrathin O-rings, got rid of another 800 grams. Most people would be happy at that, but there was scope to take things further by replacing the stock nuts and bolts holding everything to the forks and wheels. A company called Racebolt produce one hell of a range of titanium trick bits for the Suzuki, including caliper bolts, pinch bolts, spindle nuts and discs bolts. Combined together, the package saved over 300grams of precious un-sprung weight, so it was a no-brainer. As a rough guide, I learned that titanium alternatives weighed around 40% lighter than the Suzuki’s stock offerings, and another thing I learned was not to use them bareback against other metals without some kind of barrier. I looked at Leon as if he was pissed when he started greasing up my caliper bolts, but the small amount of copper slip he used on them was there to stop the aluminium from reacting with the titanium and causing the two materials to fuse together. He also advocated using Loctite on any components that weren’t often unbolted, and insisted every nut and bolt, big or small, was torqued up correctly to the required tolerances. As you’d hope for someone in his position, the guy was an utter professional, not leaving anything to chance or being tempted by shortcuts. It was a full-on day’s graft, crammed with insight, that ended 12 hours after it had started, being rounded off by a much-anticipated weigh-in on dual scales. Minus the Crowe Performance race fairings, that will add 6.3kg to the mix when we fit them next issue, the bike’s mass had been dropped to just 167kg – a staggering 35kg less than when we’d started.

Of course, with more time and more money, there are still plenty of ways to drop the weight further. I’ve got my eyes on some DB Holders front and rear subframes that are set to lose another 500grams between them, and there’s also the chance to try some carbon wheels that should bring the completed bike comfortably below 170kilos. But even as it stands, with the fairing weight added in (173kg), the power-to-weight ratio has already crested the magic horsepower-to-kilo ratio with a reading of 1.07bhp-to-kilogram, and that’s before we factor in the performance gains from the Yoshi exhaust. It’s fair to say we’re on the right track, but there’s still a lot more to do to this bike before its fit for purpose. So where do we go from here? Well, now we’ve lost the Suzuki’s blubber, it’s time to make it handle like a good’un. So next issue we’ll be focusing on bettering its controls, optimising its ergonomics and kitting it out with proper track suspension. And, if you’re sat at home thinking you’ve got a few ideas to help us with our build, make sure to get in touch.

Words: Bruce Wilson