Memorable Motorcycle: Honda RS125R

September 5, 2012
Frank Melling
Frank Melling
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Our Memorable Motorcycles expert, Frank Melling also is the organizer of the British vintage motorcycle extravaganza known as Thundersprint. Melling began riding five decades ago and remains as much in love with motorcycles as when he drove his first bike into a cow shed wall aged ten. In the last 50 years, Melling has competed in every form of motorcycle sport and now declares himself to be too old to grow up and be sensible.

Melling gets to know the Honda RS125R GP bike on track and comes back with a new found respect for the machine.
Melling gets to know the Honda RS125R GP bike at the Anglesey Circuit – confronted by the remarkable performance and engineering crammed into the 125 tiddler.

There is a very apposite saying amongst racers when they hear armchair experts giving their opinions. It’s this: “The track looks very different on the action side of the Armco.” Truly putting the racing world to rights, while watching TV, is a heck of a lot easier than pitching a bike into a corner at 100 mph.

I must confess to being guilty as charged in this respect because of the numerous critical comments I have made about 125 GP racing. Now, having ridden a 125 GP bike, I understand why Grand Prix insiders always considered the 125s to be an ideal feeder class for MotoGP. In short, these tiny race bikes are miniature versions of full on Grand Prix machines.

The difference between a GP bike and a conventional race bike is difficult to overstate and this begins right at the core of the motorcycle. The Honda RS125R was sold as a serious, over the counter race bike and wasn’t cheap at $13,000. However, the sales ticket really only bought the would-be GP racer the right to spend a lot more money in getting the bike competitive. To get an RS125 to race winning standard, a further $18-20,000 is needed. Now the price tag is a hefty $30,000 plus – which is a long way from entry-level racing.

Our test bike is the sister of the one used by teenage superstar Joe Francis, in the 125cc class of British Superbike, and to compete at this level the basic bike has to be very heavily modified.

The heart of the motorcycle is a 54mm x 54.5mm single-cylinder, six-speed, 2-stroke engine which, on paper at least, looks deceptively simple. Induction is through a crankcase-mounted reed valve and the pre-mix fuel is fed through an old fashioned, but huge, 40mm carburetor. However, the only parts of Joe’s bike which remain standard are the crankcase and clutch. The cylinder barrel, cylinder head and exhaust are all “A” kit, top specification. The radiator is also a GP level item.

The result of this package is in an incredible 44 horsepower at 13,750 rpm – vastly more power per cc than a MotoGP bike makes.

The Honda RS125R weighs a meager 154 pounds on the start line.
The RS125R kitted out for British Superbike competitor and GP prospect Joe Francis packs a considerable amount of performance into a shockingly light 154 pounds.

Although on paper a very simple machine, the reality is that Joe’s Honda is an extremely sophisticated piece of motorcycle engineering. The BPS ignition has full data logging, including a detonation counter, without which it would be almost impossible to race the bike.

The rest of the bike isn’t far behind the engine in modification. The alloy spar frame is of massive proportions for such a small, and featherlight, bike and the swingarm is built to the same standards. The frame, swingarm and rear brake are the only things which are retained from the original Honda. The Honda front forks are completely re-worked internally by British suspension experts, Maxton Engineering, and the rear shock is now an Ohlin TTX unit.

A special seat and tank unit large enough to accommodate Joe, who is heading towards six feet tall, are used and at the front a Brembo XA3 Radial Caliper and Brembo Floating Disk stop the bike. And truly, stop is the most accurate word which can be used.

Total weight, on the start line, is a startling 154 pounds. This is a bike which you don’t so much run up a ramp into the back of the van but rather merely lift in!

Before I am allowed to ride the bike I need the essential briefing from Joe’s Dad, Troy. If I ride too slowly, and don’t keep the temperature above 50 degrees Celsius I will cold seize the bike. I would also hot seize it, should I run the bike too hard at low speeds. If the detonation counter registers repeated hits I will blow the engine up.

The RS125R is sleek and boasts 44 horsepower at 13 750 rpm.
The RS125R claims 44 horsepower, with the high-strung 2-stroke requiring vigilance to the thin powerband and slim tolerances.

The detonation counter is the golden key to performance on 125s. The carburation and ignition timing are set as close to the point of seizing as is possible and the det counter gives a warning of pre-ignition. The closer the tuner can run the bike to the point of seizure the more power it will make – but the slightest error will mean a wrecked engine. It’s not slot machine, stupid gambling but a sophisticated game of poker against the weather, fuel, track conditions and rider style on any given lap.

Joe then joins in the fun by warning me about the dangers of trail braking into the corner. To (mis) quote the Holy Beach Boys of California. “We’re going to have fun, fun, fun until Troy takes the GP bike away.”

Having spent a lifetime racing, and riding, race bikes I am hyper sensitive to the body language of a race bike and the staccato crackle which emanates from the tiny stinger of the Honda tells me all I need to know: this is a serious race bike.

Because of Joe’s height, there is plenty of room – a surprising amount in view of the tiny overall size of the bike – but there is no debate that this is a full-on GP riding position with the footrests set high, and well to the rear of the bike, and the ‘bars low and narrow.

With the engine warmed up, I am given permission to coax the little Honda on to the fabulous Anglesey race track. The conditions are good – cool but sunny and dry – and, as far as I am concerned, just a normal Anglesey sea breeze.

The motor is sweet and eager. It picks up easily from zero rpm but getting the bike to move is a rather inelegant series of hops as the race clutch bites viciously and the power dies instantly.

The Anglesey track is wide, ultra grippy – and empty. I am grateful for all three as I tip toe out feeling very stressed. The problem is that the Honda can only be ridden one way: hard. There’s no hiding place and nowhere to learn gently: the bike simply demands to be mastered.

Braking on the Honda RS125R is one of the most difficult tasks to master  as the Brembo calipers will lock the front wheel solid at 120 mph without a gentle touch.
Braking on the Honda RS125R proves a difficult task to master, as the Brembo calipers will lock the front wheel solid at 120 mph without a gentle touch. It’s almost like you need to be a Grand Prix racer…

Once the motor clears the excess oil from being warmed up it jumps into the powerband in half a blink of an eye. Joe tells me to change gear at 13,000 rpm but the digital tachometer is almost impossible to see so I rely on the Formula 1 type rpm indicator. Five red lights, no clutch and the lightest of touches on the gear lever allows the quickshifter to engage the next higher gear and the process starts all over again.

It’s relentless, exhausting and a galaxy away from a classic race bike or even the road bike derived Superbikes I have ridden in the past. Rev. Change. Rev. Change. The process is infinite.

Not that I have much of a problem with the power. 44 hp is well within my comfort zone in terms of acceleration and top end speed – the real culture shock is stopping. With the latest Dunlop slicks, it is difficult to articulate just how fast this bike stops. The Honda decelerates from 100 to 30 mph in yards for Anglesey’s slowest chicane – and with only the gentlest of pressure. The Brembo calipers will simply lock the front wheel solid at 120 mph – with one-finger pressure – and the rider workload is immense.

After ten laps I am aching with the effort of locking my arms and trying to hold up nearly 200 pounds of rider. This is why GP riders are light, small and ultra-athletic: there is so much g force that big lumps like me get crushed in the deceleration.

The brakes are also another reason why GP gurus like 125s. Joe has warned that the wheel will lock in an instant when the point of no return is reached. The young rider who can trail brake right up to 99.999% – and not crash – is going to be the MotoGP star of the future.

I am fit for my age and, in particular, have good aerobic performance. Braking apart, it’s not so much the physical effort of riding the Honda which is exhausting but the mental commitment the bike demands.

Joe Francis  far left  and his family: Troy and Sharon  his mother and father  Jacob  his younger brother  and Sean the racing teddy.
Joe Francis and his family: Troy and Sharon (his mother and father) Jacob (his brother) and Sean the racing teddy.

Every inch of the circuit has to be ridden. There is no downtime, nowhere to relax or take a break – just thought and effort. The chassis is taut beyond belief and so willing to obey commands. You want to tip in hard – no problem. Change line – available in an instant. Tighten a racing line: yes sir. But all at a cost – and the price is constant rider input. Every fraction of every second you need to be giving commands to the bike.

It’s a busy ride too. The little Honda wheelies out of corners so you move your weight forward and what I thought was no more than a mild sea breeze blows the bike all over the track.

So it’s tuck in; change on the lights; change on the lights; change on the lights; stay tight behind the bubble, caress the brake; move back to keep the bike balanced; blip the throttle, release the brakes and come down three gears; throttle pinned; slide forward to kill the wheelie; change on the lights. And so on for every inch of the track – without any break.

I brought the bike back to the Francis family, a changed rider – full of admiration for Joe and his racing compatriots and delighted that Troy had his beloved bike returned without any scratches! And I’m also deeply grateful that I race such a lovely, soppy Labrador puppy of a race bike which is my G.50.

My thanks to the Francis family and to the Anglesey Race Circuit for allowing us to use their wonderful track.