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Making Sense of Engine’s Bore and Stroke

We were treated to an all-new Yamaha YZF-R1 for this year. Poring over the specification sheet we found that the engine’s bore and stroke has changed i.e. larger bores and shorter strokes. And yes, it revs higher.

What is bore and stroke?

To put it simply, the bore is the hole the piston sits in. Stroke, on the other hand, is the length that the piston needs to travel between its highest and lowest points.

But why is that?

The relationship between an engine’s bore and stroke determine, to an extent, how it makes its power. For a given capacity, ‘long stroke’ engines – ie those with a relatively long stroke in relation to the bore size – will tend to be relatively low revving but with strong low down power, while ‘short stroke’ or ‘oversquare’ motors – short stroke with a wide bore – will be able to rev higher. And, because more revs equal more horsepower (horsepower = torque x rpm divided by 5252, so increase the revs and the bhp increases too), manufacturers are always looking at ways of safely increasing the upper rev limit of their motors.

One of the major factors determining an engine’s upper rev limit is piston speed. For every revolution of an engine, the piston moves up from the bottom of its stroke (bottom dead centre or BDC) to the top of its stroke (top dead centre or TDC) and back again. So in the case of the ’04 R1, the 77mm wide piston goes from a standstill, travels 53.6mm up, stops, and comes back down again. At 10,000rpm it makes this journey just over 166 times each way every single second, at an average speed of 17.9 metres a second.

The stresses on a piston and conrod at high revs are massive. If the piston is forced to travel too quickly something’s going to break. Put very simply, if you reduce the distance the piston has to travel – ie its stroke – it doesn’t have to travel as fast and can make that journey more often. So that’s what Yamaha chose to do with their new R1, reducing the stroke by 4.4mm and adding 3mm to the bore. Last year’s R1 redlined at 11,750rpm, while this year’s redlines at 13,750, and makes its peak power 2000rpm further up the RPM scale.

Another way of reducing driveline stresses

Another way of reducing stresses is by using lighter materials for the pistons and connecting rods. Every moving part has momentum, and momentum is calculated by acceleration multiplied by mass. So, the more mass a moving object has, or/and the faster it moves, the higher its momentum. Lightening these parts will reduce stresses and also lets the engine rev faster.

How does an Assist Clutch Work?

We have covered the subject of the slipper clutch, now let us look at the assist clutch function. The assist function is an evolution of the slipper clutch and is fitted to an increasing number of motorcycles these days.

Why do we need the assist function?

Previously, harder clutch springs are required for high powered motorcycle engines in order to force the clutch plates and friction plates together, in order to maximise power transfer. Cutch springs that are too light can cause the plates to slip past each other, especially under hard acceleration.

Problem is, the clutch lever will feel very stiff as we need more finger pressure to overcome the springs’ force. It becomes even worse when the bike is accelerating hard and at speed, as the clutch’s centrifugal force pushes the plates in. Not only that, the gear lever can also feel really when using a quickshifter.

So how does the assist function work?

As with the slipper clutch, there are also ramps on the clutch’s pressure plate. However, these ramps face the other way, which cause the pressure plate to push inside onto the clutch plates for more positive engagement. In other words, less of the engine’s power is wasted from clutch slippage.

The takeaway from this is we can now use lighter clutch springs, allowing for a lighter pull on the clutch lever. It is especially useful when your motorcycle does not have a quickshifter. Additionally, shifting with the quickshifter can be potentially faster and the gear lever feels softer.

How does a Slipper Clutch Work

The slipper clutch is a common feature in road motorcycles nowadays, compared to when it was used in racing exclusively. Even some “performance” kapchais are equipped with it.

Why do we need a slipper clutch?

We are familiar with that deceleration when we shut off the throttle, or when we downshift. That is called engine braking or back torque. It is especially strong on four-stroke motorcycles with bigger engines that produce higher torque. The higher the engine’s torque, the higher its back torque too.

This engine braking can become intrusive, especially when we downshift to aggressively or we accidentally downshift to a gear that is too low. It can cause the rear wheel to hop, or even lock up momentarily. It is not something we want as we are tipping the bike into a corner, and certainly when the road is wet.

How does it work?

That is exactly why the slipper clutch was developed for: To reduce the engine’s back torque through the clutch plates to the transmission and to the final drive.

Slipper clutches usually consists of ramps that would cause the clutch basket to disengage or in other words, “slip” when the rear wheel tries to drive the engine faster above a certain deceleration threshold.

These angled ramps let the clutch faces which are normally meshed together under acceleration and normal riding to pull apart and disengaging the plates when there is too much back torque. Consequently, the rear tyre continue to rotate. It also decreases wear and tear on other transmission and engine parts due to the engine overrevving.

However, on some more sophisticated bikes (read: expensive), the slipper clutch works in conjunction with an electronic feature called engine braking control which regulates the engine speed to avoid clutch hop altogether. But that is a story for another day.

Triumph Thruxton – Where did the Name come From?

Following the news of an upcoming Triumph Thruxton 400 to replace the Bonneville Thruxton R 1200, let us take a look at the origin of the Thruxton name.

The Thruxton name plays a significant part in the marque’s history, just like the Daytona, Bonneville, Speedmaster, Trophy, Speed Twin. This is why Triumph decided to keep the name running albeit in the 400cc range, after stopping production of the 1200cc model.

What is Thruxton?

More like where, actually. It is the name of the Thruxton Circuit, in Hampshire, England.

It began as a military airbase, known as RAF Thruxton in 1942, and was home to troop carrying aircraft of both the RAF and USAAF. In fact, some of the airborne troops who took part in D-Day, 1944, took off from from this airbase.

The circuit was laid out along the perimeter of the runway since the 1950s, but the longer and present track was only fully established in 1968. History, it has since hosted the Thruxton 500 endurance race (1960-1964, 1969-1977), British Formula 3, British Formula 2, and many more. The circuit remains part of the British Superbike Championship (BSB) and British Touring Car Championship (BTCC) calendar until today.

The Thruxton 500

However, the most relevant and important race in this story was the Thruxton 500.

It all began as a 9-hour endurance race for motorcycles in 1955, followed by another two in 1956 and 1957. This 9-hour race evolved into the famous Thruxton 500 mile (800km) race from 1958.

The Thruxton 500 was a production motorcycle race, meaning the motorcycles being raced must be available to the public, not unlike the current day FIM Endurance World Championship. Each bike entered will be ridden by two riders on rotation.

Anyway, Triumph entered the inaugural endurance race in 1958 with a Bonneville T120, entered with Mike “The Bike” Hailwood and Dan Shorey as riders. They won.

The race soon caught the attention of the public. As such, motorcycle manufacturers were keen to win it to showcase their products’ performance. “Win on Sunday, sell on Monday,” even before Soichiro Honda made those words famous.

Triumph won again in 1961 with Tony Godfrey and John Holder after being runner ups to the BMW and AJS in 1959 and 1960. It was this win that spurred the Triumph factory to build the T120R Thruxton, which was hand-built by a team of Triumph technicians using specially picked components and precision-machined cylinder heads and crankcases. Peak power was increased and each ‘Thruxton’ engine was bench tested to deliver around 53 bhp (40 kW) at 6,800 rpm with a safe rev ceiling of 7,200 rpm. Only 52 of the Thruxton T120Rs were built in 1964/5 to meet homologation requirements for production racing. About 100 more machines were subsequently manufactured and supplied to selected dealers and riders.

It was one of the rarest Triumph motorcycles.

Rise of the modern Triumph Thruxton

In 2004, the new Triumph factory based in Hinckley, England introduced the Thruxton 900. The engine was derived from the Bonneville lineup, but has new cams and pistons 90mm pistons, taking capacity to 865 cc and power up to 70 bhp. The crank was a 360°, which meant both pistons rose and fell together. Triumph was smart to sell the Thruxton 900 as the café racer of the Bonneville lineup. (Tom Cruise rode it in The Edge of Tomorrow, by the way.)

The company then introduced the new Thruxton in 2016. It used the new 1200cc, 270º, liquid-cooled engine. There were two variants, one the standard while the “R” got Ohlins shocks, Showa forks, and Brembo brakes.

The Thruxton has since enjoyed good sales the world over, although the later-launched Boneville Bobber pipped it as the best selling Triumph.

Then, in 2024, Triumph announced the Thruxton Final Edition as they moved the performance Bonneville to the Speed Twin.

Closing

Long live the Triumph Thruxton!

How to Tell if Your Riding Gear is Genuine (Part 2) – RS Taichi

Continuing this series, let us check out another brand, the world-renowned RS Taichi.

To recap, we wanted to know how the makers of motorcycle riding gear take steps to ensure that you and I buy are genuine. These major manufacturers have put in much effort and cost to ensure that their products conform to safety standards in order to protect us.

However, the advent of online shopping platforms have created the problem of dishonest sellers parading copied and fake wares. And these shopping platforms are doing nothing to stop them.

Thus the onus falls back on our shoulders to ensure that we are spending our hard-earned money on genuine products.

**Courtesy of Hodaka Motoworld Singapore**

Who is RS Taichi?

The brand was founded my a professional motocross racer, Taichi Yoshimura in 1975, in Osaka, Japan. Yoshimura was raced for the Suzuki and Honda factory teams in motocross, and had the distinction of giving Honda their very first win in motocross racing.

The first RS Taichi product was a gear bag, before going on to making racing leather suits in 1978. Now, RS Taichi makes the complete range of motorcycle rider gear and accessories, from helmets to jackets, gloves, pants, shoes, inner wear, leather suits, bags, protectors, and more.

How can you detect a genuine RS Taichi product?

1. Look for the yellow Taichi tag in your jacket, gloves, pants, and bag.

2. Use a torchlight or your phone’s flashlight and shine through the tag.

3. You should see many Taichi logos.

Counterfeit RS Taichi products may have the tag, but the hologram will not show.

Conclusion

Alright, we have covered Komine and now RS Taichi, and we shall continue to cover other brands. Again, buy your riding gear from official channels. It is not worth saving a few bucks but compromising your safety.

Adventure Motorcycles for New Riders (2025) – Part 2

Alright, let us continue with part 2 of this Adventure Motorcycles for New Riders (2025). But before we proceed further, let us clarify that “adventure motorcycles” describe motorcycles that have more fuel capacity and long-range comfort, compared to enduro motorcycles. In other words, these motorcycles retain some off-road capabilities and can be used for touring. Hence they are also known as dual-sport motorcycles.

Let us also move up the scale a bit and into the sub-500cc range.

6. KTM 390 Adventure

There are actually two versions of this bike i.e the standard 390 Adventure and the (much) more off-road oriented 390 Adventure R.

Launched in 2021 with cast alloy wheels, it underwent a revision for 2023, featuring wire spoked wheels.

Then, at EICMA last year, KTM revealed the long-awaited “R” version which was pretty much a totally new motorcycle including a new engine, suspension, bodywork, frame, swingarm, 27-inch front wheel, electronics. Come to think of it, it is much more like the smaller version of the 790/890 Adventure R.

In any case, the 390 Adventure was a hoot to ride both on the road and off-road, thrilling both new and veteran riders. However, wait for the “R” version if you plan on more exploring and off-roading.

(Specifications for the KTM 390 Adventure)

373cc, single-cylinder, DOHC, four-valve, liquid-cooled engine, producing 44hp, 37Nm.
14.5-litre fuel tank, 159kg (dry).
855mm seat height.
Pros: Torquey engine, superb suspension, hard-edged.
Cons: Standard suspension tuning is a bit hard.
Selling price: RM33,800.

7. Royal Enfield Himalayan 450

The Royal Enfield Himalayan offers reliability, toughness, simplicity, versatility, and affordability all at one go. However, that toughness has a price in terms of weight. The 450 is the new model and features a bigger engine and TFT screen with smartphone connectivity, and there are 4 trims.

452cc, single-cylinder, DOHC, four-valve, liquid-cooled engine, producing 40hp at 8,000, 40Nm at 5,500 RPM.
17-litre fuel tank, 191kg (dry).
825mm seat height.
Pros: Simple, reliable, versatile.
Cons: Rather heavy.
Selling price: From RM30,600.

8. CFMoto 450MT/450MT-X

A high-spec’ed motorcycle at a competitive price: Adjustable KYB suspension, TFT screen, J.Juan brakes, adjustable windscreen (although manual), switchable rear wheel ABS via a dedicated button, etc. This bike is gear more towards off-road riding with 21-inch front and 18-inch rear wheels, but has a low seat height. Go for the MT-X version for just RM2,000 more and you will get three aluminium cases.

449cc, parallel-twin, 270º DOHC, four-valve, liquid-cooled engine, producing 44hp at 8,500, 44Nm at 6,250 RPM.
17.5-litre fuel tank, 175kg (dry).
820mm seat height.
Pros: Good features, light, low seat height.
Cons: Abrupt throttle action.
Selling price: RM28,800 (450MT), RM30,888 (450MT-X).

9. Triumph Scrambler 400X

Not as off-road oriented as the Scrambler 1200 but does a decent job with its longer travel suspension. But as with other Triumphs, the 400 platform is nimble, has a torque and entertaining engine, and superb suspension. And, the Scrambler 400 X comes equipped with a whole range of accessories, making it look really butch at a great price.

398cc, parallel-twin, 270º DOHC, four-valve, liquid-cooled engine, producing 39.5hp at 8,500, 37.5Nm at 6,500 RPM.
13-litre fuel tank, 179kg (wet).
835mm seat height.
Pros: Easy to ride, stylish, entertaining.
Cons: Very short 1st and 2nd gears.
Selling price: RM29,900.

10. Benelli TRK 502X

The TRK 502X is the adventure version with 19-inch front and 17-inch rear wheels, while the TRK 502 is the sport-touring version with 17-inch wheels on both ends. Truth be told, this product lineup is kind of long in the tooth, although it was updated recently. But, you do get dual front brakes, and it is probably the best for long-distance touring among the group here.

500cc, parallel-twin, four-valve, liquid-cooled engine, producing 48hp at 8,500, 45Nm at 6,000 RPM.
20-litre fuel tank, 213kg (dry).
840mm seat height.
Pros: Well appointed for long-distance riding.
Cons: It is heavy and feels heavy.
Selling price: RM35,288.

Closing

So there you have it, 10 most appropriate adventure motorcycles for new riders. It has to be said that motorcycles have come a long way and even a 250cc adventure bike can do wonders plus saving you a few bucks to be spent on riding gear.

There are several models missing in our list, including the Honda CB500X and Fantic Caballero 500. These two are fantastic bikes, nonetheless so we will write further features about them in the near future.

Adventure Motorcycles for New Riders (2025) – Part 1

Adventure motorcycles are already known for their comfort and versatility, hence why the segment is still growing. While we ride 99.9% of the time on paved roads, adventure bikes still provide many advantages, including long-travel suspension is able to soak up bumps and irregularities, tall ride height which gives the ride great all-round vision, comfortable ergonomics, and the ability to be fitted with luggage and bags.

Then of course, there is ever present capability for off-road exploring although that potential depends on the specific motorcycle and rider.

Speaking of the rider, it is perhaps unwise for a new rider get the most powerful and fastest adventure bike, especially if you plan to do some off-roading. So, here are XX adventure motorcycles for new riders, which we have updated for 2025.

1. Honda CRF250 Rally

It all began with the CRF250L in 2013, then the CRF250L Adventure, before becoming the present CRF250 Rally. Built to look like the CRF450 Rally Dakar racer, this bike looks the part and is easy to ride. There is even a built-in tool space in the left underseat panel.

250cc, single cylinder engine, which does 24hp at 9,000 RPM, 23Nm at 6,000 RPM.
12.8-litre fuel tank, 153kg.
885mm seat height.
Selling price: RM28,599.
Pros: Easy to ride, lightweight.
Cons: Seat height may be too tall for new riders.

2. Modenas Versys-X 250

The Versys-X 250 is a popular model as it has a lower seat height, and is gear more towards a sport-tourer although it does have some off-road capabilities. But get this: Modenas equips the bike with a pair of side cases as standard equipment in Malaysia.

249cc, parallel-twin engine, producing 32.5hp at 11,500 RPM, 21.7Nm at 10,000 RPM.
17-litre fuel tank, 181kg.
815mm seat height.
Selling price: RM24,900.
Pros: Fast for a small cc adventure bike, low seat height.
Cons: Peaky engine (needs lotsa revs), rudimentary suspension.

3. Suzuki V-Strom 250SX

The V-Strom 250SX is a long-awaited model and had just been launched in Malaysia last year. All we can say is it was worth the wait. While the engine does not boost any new tech and looked underpowered on paper, it was full of low- and mid-range torque. And when coupled to a superb suspension, the bike was actually sweet to ride. In fact, it felt a lot like riding the KTM 250 Adventure, but at a much lower price. Build quality was the best even beating out the Honda.

249cc, single-cylinder, SOHC, two-valve, oil-cooled engine, producing 26hp, 24Nm.
12-litre fuel tank, 167kg.
835mm seat height.
Selling price: RM17,800.
Pros: Torquey engine, compliant suspension, great value for money.
Cons: No assist and slipper clutch.

4. KTM 250 Adventure

The KTM 250 Adventure is gear more towards the adventure side of purpose, hence you can hit the trails put of the box. However, it is also a practical bike everyday riding and touring. The suspension is also more supple compared to its 390 Adventure sibling’s. It is also much simpler.

249cc, single-cylinder, DOHC, four-valve, liquid-cooled engine, producing 29.5hp at 9,3000 RPM, 22.72Nm at 7,300 RPM.
14.5-litre fuel tank, 156kg.
855mm seat height.
Selling price: RM24,000
Pros: Torquey engine, compliant suspension, the most adventure-ready of the lot.
Cons: No assist and slipper clutch.

5. BMW G 310 GS

This bike always seems to escape everyone’s attention for some reason. Is it due to price? Maintenance costs? Reliability? Do let us know because we have reviewed it and found it to be a rather good all-rounder.

313cc, single-cylinder, DOHC, four-valve, liquid-cooled engine, producing 34hp at 9,250 RPM, 28Nm at 7,500 RPM.
11.5-litre fuel tank, 175kg.
855mm seat height.
Selling price: RM31,500
Pros: Torquey engine, compliant suspension, best all-rounder.
Cons: You tell us!

The Greatest Honda V4 Motorcycles (Part 2)

Welcome back to Part 2 of our countdown of the greatest Honda V4 motorcycles. The remaining five are so iconic that we are sure you have heard of them.

5. Honda VFR750/800 (1987-2013)

Among all of Honda’s V4 production motorcycles, the VFR750 and the later VFR800 were the most successful in terms of numbers sold. In fact, they were probably some of the best motorcycles ever made.

Comfort was excellent, great build quality, good handling and equipment, it was the classiest motorcycle you could buy. Honda may have since revived the VFR800 in face-lifted form along with the Crossrunner, both of which are decent, but those ‘80s and ‘90s VFR750s can still claim to being the greatest V4s of all.

4. Honda RVF750R (RC45) (1994-1999)

The RVF750R was launched in 1994 as a long-awaited and much anticipated successor to Honda’s first all-conquering V4 superbike, the VFR750R RC30.

Closely-related to the RC30, it uses a 90º V4 with gear-driven cams housed in an aluminium twin spar frame featuring a single-sided swing arm. However, it was actually all-new and co-developed by Honda’s racing division, HRC, and Honda R&D. Differences included a shorter stroke, more compact design and fuel-injection. In its last racing form, the engine made more peak horsepower than even Mick Doohan’s NSR500 two-stroke GP bike.

Although highly successful at the Isle of Man TT and in world endurance, it won only one WSB crown. While on the road, its road legal 120bhp was nothing special. It was of course supremely expensive at nearly £18,000.

3. Honda VFR400R NC30/RVF400R (1989-1996)

What? A 400cc V4 in the Top 3? Well, why not? The VFR400R and later RVF400R were the little brothers to the RC30 and RVF750R respectively. They were much more affordable and accessible to the man in the street.

Both were produced in parallel to their 750 siblings although, as mass market bikes, had lesser spec, fewer exotic materials and were not hand-built. Both were also the result of a then-prevailing Japanese licensing law that favoured 400cc machines. Several units made it to Malaysia and certainly in Singapore.

The NC30 was definitely among the best: effectively a ‘slightly smaller RC30’ with sublime handling and an impressively flexible V4 producing 59bhp. The RVF400R was said to be even better but unfortunately was short-lived.

2. Honda RC213-V (2015-2016)

Conceived as a road-going replica of the then RC213V MotoGP machine, it is as close to that bike as was possible and practical with little concern given to cost.

Around 250 were built in total, hand-made by small teams of hand-picked engineers. Although road regulations limited performance to 159bhp, its chassis boasted the best of everything including Ohlins TTX25 gas forks, forged magnesium wheels and a slimline full-colour TFT dash while, with the optional Sports Kit fitted, intended for track use which includes a revised ECU and exhaust together unleashing 215bhp, it’s as close to the full works V4 MotoGP experience mere mortals can buy.

Which is as it should be, considering the £137,000 price.

1. Honda VFR750R (RC30) (1987-1990)

The RC30 remains the best Honda V4 ever built. There we have said it.

Timed to promote Honda’s new VFR V4s, it conceived to exploit the new World Superbike and world endurance racing regulations (based on 750cc production machines). As such it was developed with no expense-spared by HRC.

As a homologation special racer it won straight out of the crate – not just in WSB (becoming the first champion in 1988), but in endurance, F1 and at the TT. It also dominated Malaysian superbikes.

Not to mention the most beautiful amongst them.

The Greatest Honda V4 Motorcycles (Part 1)

Being the world’s largest motorcycle maker would invariably mean you would have produced all sorts of motorcycles and the engines that power them. However, Honda loves the V4 engine in particular hence so many of their iconic motorcycles were V4-powered. -However, regulatory bodies do not share such enthusiasm and the Euro5 emission had put an end to any V4 bike in Honda’s line up. So, here is a fond look at the greatest Honda V4 motorcycles of yesteryears.

10. Honda VF750F Interceptor (1982-1985)

Honda’s V4 ‘project’ began with the ill-fated NR500 GP racer in 1978, but their V4 road bike story began with the VF750S Sabre and VF750F Interceptor in 1983.

The S was a semi-cruiser roadster, while the F had a half-fairing. Both were based on the same 90º V4, with the S being shaft driven and the F via a chain. They were both considered high-tech at the time, being liquid-cooled and 16 valves. The VF750F in particular was an advanced, impressive design with box-section frame, nose fairing, 16-inch front wheel, adjustable suspension and more.

Unfortunately, early versions were blighted by premature cam wear, so much so they became known as the ‘chocolate cam’ V4s. Honda initially ignored the problem, which was caused by inadequate oil flow, then eventually improved the design, eliminating the fault. But, following the folly of the NR racer, it was too late to save the V4 the bikes’ reputation, hence the short model lifespan.

9. Honda VF1000R (1984-1987)

Honda was not content of building just a 750cc V4, they went big the next year by introducing three(!) 1000cc, in addition to a 400cc V4s.

The R was intended to be the ultimate, showcasing all Honda’s latest technology as a successor to the CB1100R. Where the other 1000s (and 750s) had chain-driven cams, the R had a sophisticated gear-driven arrangement.

It also had anti-dive forks, GP-alike Comstar wheels, a box-section frame, twin radiators and race-style bodywork comprising a full-fairing, removable seat hump and twin endurance style headlights, a year before Suzuki’s new GSX-R750.

High compression heads helped produce 122bhp and drive the VF onto 150mph, making it the fastest bike of the day (prior to the Kawasaki GPz900R). Unfortunately, all that tech and gear-driven cams also made the R quite heavy. It was also ridiculously expensive hence there are not many examples these days.

8. Honda VF400F (1983-1987)

Despite Honda’s intends and purposes to dominate the big bike market with the VF750 and VF1000, many enthusiasts say that the best Honda V4 of the era was the VF400F.

The engine had 16 valves and produced 55hp, very close to Yamaha’s RD350 YPVS two-stroke’s 59hp. It also had those iconic inboard disc brakes and bikini fairings.

Honda released the fully-faired VF500F in Europe the next year. It had conventional disc brakes, and 70hp. And it did not have cam issues.

7. Honda VFR1200F (2009-2017)

Wait! Where is the VFR750/VFR800? Do not worry, those are further up the list, as we are counting down based on merit, rather than when they were produced.

In fact, the VFR1200F was the successor to the VFR750/800. However, the bike’s development was fraught with prolonged teases and delays.

The all-new 1237cc V4 engine was actually good: producing 170bhp, lots of midrange torque and power, and featuring shaft-drive. From 2010, it became the platform to debut Honda’s optional, semi-automatic ‘DCT’ gearbox.

Unfortunately, the buying public during the time found it was too heavy; the ‘sports-tourer’ concept was by then outdated; its styling was disliked; its fuel tank was too small and lack of high-spec tech, with an old school dash and no electronic rider aids, compared to its peers.

6. Honda NR750 (1992)

In many ways the NR750 was not only the ultimate Honda V4, it was the most exotic motorcycle of all – ever.

Hand-built, no expense-spared road-going ‘celebration’ bike to mark Honda’s oval-piston V4 racing project, the NR750 could very well be Honda’s most exotic production motorcycle. Ever.

Honda had first proposed the oval piston concept in the NR500 racer in 1978. It was a four-stroke V4 GP bike but with oval pistons with twin con rods and eight valves per cylinder to create the power of a V8. The company wanted to show the world that their four-strokes could take the fight to two-stroke GP bikes of that era. Unfortunately, the project did not yield the success they sought, and Honda went on to create firstly the NS500 three-cylinder two-stroke racer, and finally the world-conquering NSR500 four-cylinder two-stroke GP machines.

Back to the NR750 road bike, it had 125bhp and too much weight. But its gorgeous styling, plus high-end specs such as a carbon fibre single-sided swing arm, titanium con rods, inverted forks, etc. put it above production bikes of the era. Only 200 were built with a new price of £38,000 in 1992.

To be continued…

What is a 270-Degree Crank Engine?

‘It’s powered by a parallel twin with a 270-degree crank’ is such a commonplace now that riders probably do not pay attention to it anymore. However, they may notice the exhaust note sounds a little different than the ‘other’ parallel twins.

To understand this, let us go back a bit to another article about the CP4 a.k.a. crossplane engine. We spoke at length about the crankshaft and its crank pins (journals) where the big ends of the pistons’ connecting rods are mounted to.

In a traditional parallel-twin engine, the journals are spaced at 180° apart: When one piston is at the top of its stroke (called top dead centre, or TDC), the other is at the bottom of its stroke (called bottom dead centre, or BDC). In other words, one goes up, the other goes down.

Now, anything that has mass creates inertia, hence the primary force of one piston nearing the top is (nearly) balanced by the other piston nearing the bottom. However, these movements create a side-to-side motion called the ‘rocking couple’ which needs to be damped with counter rotating weights. Some riders do not like the lumpy exhaust note.

Certain manufacturers opt for the 360° crank to counter this, meaning both pistons rise and fall at the same time. Now you have no rocking couple, but the primary forces are X2. Several motorcycles actually used this format up until not long ago such as the old Triumph Bonnevilles (prior to the liquid-cooled version), the old BMW F 800 series. However, the 360° crank parallel-twin sounds like Boxer flat-twin.

So, here comes the 270° crank parallel-twin. Yamaha had debuted it in the 10-valve, 849cc, TRX850 in 1995/1996. Production of the bike stopped in 2011, but Yamaha believed in the engine layout’s potential, thus bringing it back as the CP2 (crossplane-2) in the MT-07 in 2014.

As hinted by the term, the crank journals are spaced 270° degrees apart. After one piston fires, the crankshaft rotates 270° before firing the other. No, the primary forces are not balanced, which is countered by the use of a balancer shaft.

The rocking couple still exists, but the effect is less pronounced due to the uneven firing order. The pistons are also always moving, unlike in a 360 or 180-degree twin, reducing inertia. However, the secondary forces in a 270° parallel twin are balanced.

This offset firing order gives the parallel twin a 90° V-twin-like exhaust note.

The true appeal of this engine format is packaging. In other words, it requires less space in a motorcycle’s frame, compared to a V-Twin as it the V-Twin is longer front-to-back. Also, the entire engine can be moved closer to the front wheel to promote better chassis balance at the front for better handling. A third advantage is that a more compact engine allows for a longer swingarm while maintaining a shorter overall wheelbase, again for quicker handling.

The list of bikes that use the 270° crank parallel-twin is long. Apart from the Yamaha MT-07, there are the Suzuki 800cc range, KTM 790 and 890 range, Triumph Bonneville, Honda X-ADV, Transalp 750, and Africa Twin, etc.

Cordura – The Wonder Material for Motorcycle Clothing?

There are many materials used to make motorcycle clothing, a far cry from just leather many decades before, following the development of different types of motorcycles for different purposes. Let us look at Cordura.

Real world evaluation

This author had the opportunity to evaluate the RS Taichi RSJ330 Cordura Hoodie during this recent trip to Guangzhou, China. It is already in the middle of the winter months, as Beijing and Shanghai are already covered in snow. Guangzhou is situated much further south, so the weather was much more pleasant: 20° Celsius during the day, and as low as 12º Celsius at night. As such, it was not exactly the feature for full-blown winter gear.

The jacket held up truly well, keeping him warm for most of the day. As Cordura is breathable, it can get blustery and cold at night but an extra shirt underneath was all that it took.

So, what is Cordura?

Cordura was developed and trademarked by E.I. du Pont de Nemours and Company (DuPont) in 1929, Cordura is currently owned by Invista, a subsidiary of Koch Industries.

DuPont’s scientists were had tried to improve upon rayon, and came across Cordura as a “high-tenacity rayon, as strong as mild steel yet able to stand up under repeated flexing.” These two properties made Cordura suitable for a wide range of products including bags, shoes, clothing.

Cordura motorcycle gear refers to protective motorcycle clothing made from Cordura fabric, a high-quality nylon material known for its exceptional abrasion resistance, tear strength, and durability, making it a popular choice for motorcycle jackets, pants, and other riding gear, providing excellent protection against impacts and scrapes in case of a crash while offering a relatively lightweight and comfortable feel compared to traditional leather options.

Key points about Cordura motorcycle gear:

Abrasion resistance: The primary benefit of Cordura is its high resistance to abrasion, meaning it can withstand significant rubbing against rough surfaces like asphalt during a slide, minimizing skin damage in a crash.
Durability: Cordura is designed to last longer than many other fabrics, making it a good investment for riders who want long-lasting protective gear.
Flexibility: While strong, Cordura can be woven into fabrics with good flexibility, allowing for a comfortable range of motion while riding.
Weatherproofing: Cordura can be treated with waterproof coatings to protect against rain and wet weather, making it suitable for all riding conditions.
Variety of options: Cordura is used in a wide range of motorcycle gear, from lightweight summer jackets with mesh panels to heavier duty touring jackets with additional protective features.

Important considerations when choosing Cordura gear:

Denier rating: The “denier” number indicates the thickness of the Cordura fibers, with higher numbers signifying greater abrasion resistance. For example, 500D, 1000D and so forth.
Armor placement: Ensure the gear has proper armor placement at key impact areas like elbows, knees, and shoulders for optimal protection.
Ventilation: Check for mesh panels or other ventilation features for comfortable riding in hot weather.

Zontes 703RR First Ride Review

Yes, it is another Zontes but hear us out as there are so much to this bike! The Zontes 703RR represents the company’s first ever sojourn into the big capacity sportbike category, by utilising their new 699cc, three-cylinder, DOHC engine which also powers the 703F adventure model. It had just been launched at EICMA, less than a month prior to our visit.

The engine was in its design stages just five years ago. What we say back then there several renderings on a computer screen, and that was it. So take away two years due to the Covid-19 lockdowns, Zontes took only three years to make it happen.

What is the Zontes 703RR?

It is the sportbike of the Zontes family and looks to be the flagship model, at least in the time being. It features a beautifully sculpted and distinctive bodywork with sharp lines, even winglets covered in aerobodies.

A short highlight of its features include:

699cc, inline-triple, DOHC engine, fed by a ram air intake. It produces 100.5hp at 11,200 RPM and 74.5Nm at 8,500 RPM. Ram air intake should add another 10hp in the upper RPMs.

The frame is real wow factor here: Each side of the twin-spar aluminium frame is cast as one piece then joined in with the other side. On the other hand ,conventional aluminium frames have their headstock and “uprights” that hold the swingarm pivot are welded onto the spars.

Zontes claims that this reduces the engine vibes and also provide better targeted stiffness vs. flex characteristics.
The subframe is also a one-piece cast aluminium component, and bolted to the back of the main frame.

Adjustable Marzocchi forks and monoshock.
Dual front disc brakes gripped by J.Juan calipers, dual-channel ABS is standard.

LED lighting all-around.
8-inch colour TFT screen complete with power modes and lap timer.

196kg wet weight.
Seat height is 795mm.

Riding the Zontes 703RR

If you like sportbikes, the seating position is so right. The ergonomics are somewhere along the lines of the Aprilia RS660 mixed with that of the Triumph Daytona 660. The clip-on handlebars are mounted slightly higher than the top of the fuel tank, so they do not put your weight onto your wrists. And that seat was so low that putting your feet down was of no issue.

The only place to test ride the bike was on a small test track at the factory’s compound. The front “straight” was just 100m long and there was a double-apex hairpin on each end, with a three-turn chicane in between. So it was tight like a small go-kart track.

Heading into the first turn, I squeezed the front brake lever with two fingers and was almost thrown out of the seat. It was THAT powerful!

Despite screwing up the corner entry from overbraking, the Zontes 703RR happily tipped into the corner without threatening to collapse the front tyre. Still in 2nd gear, I opened the throttle as the bike touched the apex and WHOOOOOOOOOP went the engine. Thankfully, the corners are marked by lines drawn on the road rather than curbs, because the bike shot all the way from the exit of the first corner to the last corner!

So, I short-shifted into 3rd and rounded the last turn, and stand the bike up quickly and rolled on the throttle to exit the corner. The 703RR just blasted down that 100m straight in a flash. The company’s CEO had insisted on building a three-cylinder engine because he prefers its strong torque and accessible horsepower.

I continued going around and around, and avoided making eye contact with those in the starting area because I did not want to be flagged in. In the end, a Zontes crew stepped almost onto the middle of the track to wave me in. I must have covered some 9 laps.

Conclusion

Yes, yes, it was a short ride but having ridden so many motorcycles before, I can confidently say that the Zontes 703RR has the chops of a great bike, although its prowess on the track needs to be discovered. But, as a midrange street superbike, the present contenders better watch their backs.

We asked Zontes Malaysia if it will make it here. The official returned a cheeky smile.

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6. KTM 390 Adventure

7. Royal Enfield Himalayan 450

8. CFMoto 450MT/450MT-X

9. Triumph Scrambler 400X

10. Benelli TRK 502X

Closing

1. Honda CRF250 Rally

2. Modenas Versys-X 250

3. Suzuki V-Strom 250SX

4. KTM 250 Adventure

5. BMW G 310 GS

5. Honda VFR750/800 (1987-2013)

4. Honda RVF750R (RC45) (1994-1999)

3. Honda VFR400R NC30/RVF400R (1989-1996)

2. Honda RC213-V (2015-2016)

1. Honda VFR750R (RC30) (1987-1990)

10. Honda VF750F Interceptor (1982-1985)

9. Honda VF1000R (1984-1987)

8. Honda VF400F (1983-1987)

7. Honda VFR1200F (2009-2017)

6. Honda NR750 (1992)

To be continued…

Real world evaluation

So, what is Cordura?

Key points about Cordura motorcycle gear:

Important considerations when choosing Cordura gear:

What is the Zontes 703RR?

Riding the Zontes 703RR

Conclusion

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