Like most biking enthusiasts, Deepak ‘Clutchless’ Vishnu developed a fascination for speed a few years ago. Alongside his friends, he would ride down to the Athirappilly Falls near Kochi and spend the morning hours practicing his cornering on the winding roads. Over time, Clutchless realised the need to work on his riding skills.
In 2016, he made his way to a race track for the first time. From his home in Kochi, he rode down to the Madras Motor Race Track in Chennai, spent five hours on the track and returned home the following day. The round trip of 1,600km in just a couple of days was hectic, but Clutchless realised he would never be speeding down a road again.
Ever since, he’s spent many hours at the race track, where besides riding, he’s had the opportunity to mingle with seasoned heads from the Indian bike racing circuit. He took those ideas back home and after his own research, started tinkering with his bike. That passion has today translated into his own state of the art workshop called UnderGround Tuning in Kochi, where he continues to work on his prized machines to bring out the best in them.
Through the experience that he’s gathered over the years, Clutchless shares the essentials that go into building a racing bike. He says that the performance of a bike depends on a few basic factors that must be taken into consideration while planning the build.
Wheelbase and the bike geometry
The fundamental difference between cruisers and racing bikes is the wheelbase. This is the horizontal distance between the centres of the front and rear wheels. Cruisers have longer wheelbase to give them better stability on the road. On the other hand, racing bikes use a shorter wheelbase for quicker turning, a sharper angle while leaning and better agility on the whole.
“Any modifications that you make in the front must have a corresponding change on the rear to maintain the geometry. For instance, if you change the rake of the motorcycle to shorten the wheelbase, the bike becomes nimbler. But at high speeds, it loses stability. So the changes must be made both in the front and rear,” says Clutchless.
Trick out your Electronic Control Unit for racing
If the engine is the heart of the bike, the Electronic Control Unit (ECU) is its brain. It mainly controls how the fuelling and ignition runs on the bike. The many sensors on the bike send data to the ECU, which in turn transmits signals to specific components for action. The data collected by the ECU allows a tuner to understand the performance and tweak settings to improve the bike’s capabilities.
“When manufacturers build a bike, they have to comply with various environmental norms. But while racing, we don’t need to follow it. So to start off, these are some basic changes that can be made through the ECU to ready the bike for racing,” Clutchless says.
The ECU is a sensitive device that is affected by changes in atmospheric temperature and pressure. Clutchless remembers a time when they had starting trouble due to a new ECU that had been installed just a day before the race. It had worked fine under the weather conditions in Bengaluru, but had acted up once at the track in Coimbatore.
“The program on the ECU would cut the ignition and we faced a lot of trouble at the start, though we did land up racing eventually,” he says.
Adjust tuning for better performance
The main idea behind tuning a bike is to improve the efficiency of the engine. It gives it the capability to deliver more power for the same amount of displacement and in turn, better its performance.
“It’s a lot of work to get the tuning in place. We first program an ECU that makes very good top-end power and at a very high RPM. Then we start dyno tuning it over multiple runs,” Clutchless says.
Dyno tuning typically means configuring the engine’s air-to-fuel ratio to establish good balance so the engine can run at its peak. It provides for greater power delivery and a smoother throttle while riding. Any changes on the bike – say for instance, if the exhaust is replaced – will have a direct impact on the bike’s tuning and must be accounted for. Most stock motorcycles have a rev limit of 9,500-10,000 rpm, which is usually raised to 12,500-13,000 rpm for racing, depending on the track and the rider’s preferences.
More fuel+air = More power
Any rider would like to maximise the power output of their machine. The power that is delivered depends on the proportion of air and fuel that is entering the engine.
“The engine is like an air pump – the more fuel and air you add, the greater power it delivers,” Clutchless says.
Modify the sprocket for higher torque
In generic terms, torque means the pulling power of a bike when in a particular gear, which means fewer gears shifts while riding. Torque can be improved through sprocketing, which essentially means modifying the sprocket to alter the gear ratio.
“You can make the rear sprocket bigger or the front sprocket smaller, depending on the track and how you want the power delivered,” Clutchless says.
Adjust suspension to improve handling
Suspension is the key to improve the handling of the bike. When the rear suspension is lowered and the front is raised, the stability improves, though it has an adverse effect on the steering.
“The springs must be changed depending on the rider’s weight. The handling of a bike is a personal preference and there can be different setups using multiple forks and shocks, depending on how the rider wants the bike to react,” Clutchless says.
Use sintered brake pads for racing
Sintered brake pads are the most preferred for their grip and performance under both wet and hot conditions. They are used over organic brake pads, which are known to deteriorate more rapidly due to wear and tear.
“Sinthering is a process where you compress copper under very high temperature and pressure. It makes the metal more wear resistant and increases its longevity. Besides that, you can increase the size of the rotor, which can make handling slightly better,” Clutchless says.
Use fibre glass for a lighter racing bike
A stock bike is firstly stripped off all unnecessary components like switches, mirrors and indicators to get it ready for racing. The overall weight of the bike can be reduced by creating the fairings and seat using fibre glass, which is much lighter.
“Carbon fibre is what is preferred around the world for racing, since it is even lighter than fibre glass. But it’s been banned in India, so fibre glass is the best bet,” Clutchless says.