Why The V-Twin Is The Standard Engine For Big Cruisers

Summary

• Cruisers thrive on emotions more than performance numbers; evoke freedom, love, rebellion.
• V-twin cruisers are powerful, reliable, but laid back for comfortable long rides.
• V-twin engines bring character, vibrations, and torque delivery for cruisers’ appeal.

Sports bikes are all about performance and adventure bikes are all about practicality. But if there’s one segment that thrives on emotion, it is the cruiser segment. When it comes to this segment, it’s no longer a game of horsepower figures, power-to-weight ratio, or top speed. It’s about what emotions these bikes evoke; whether they are of freedom, live-laugh-love, or rebellion.

Don’t get us wrong, modern V-twin cruisers are powerful and reliable, but they have a character that high-strung sports bikes can only dream of. Cruisers are more laid-back — that’s where the answer lies. Laid back, so you can munch miles on them comfortably without constantly working the gearbox and trying to stay in the powerband. But there’s more to these long-stroke V-twin engines than just character. V-twin engines are not without their technical merits. For what they are meant to do, they are bloody good at it.

In order to give you the most up-to-date and accurate information possible, the data used to compile this article was sourced from Harley-Davidson and Indian, and other authoritative sources, including Zeroto60times.com.

The History Of The V-Twins

Back in the day, motorcycles were nothing but bicycles with crude single-cylinder engines strapped to the frame. These engines were unreliable, leaked oil everywhere, and were barely stronger than the rider themself. But we’ve always wanted to go fast, and soon enough, the appeal of bigger engines grew. One of the first solutions was to plonk a second cylinder on the same crankshaft in a V configuration. Lo and behold, you have doubled the displacement while using a single cam to operate the valves in both cylinders and a single carb that shares two intake manifolds.

Indian Motorcycles was the first to develop a V-twin engine in 1903, and Harley-Davidson quickly followed suit in 1909. And this configuration has propelled both the brands to prominence today, through the Great Depression, world wars, and everything in between. In the 70s, the Japanese manufacturers joined the rally by bringing in imitations of American cruisers, which were outdated for the time. These metric cruisers arrived in style along with the American cruiser fly line, a teardrop tank, chrome panels, buckhorn handlebars, and a stepped saddle. But these cruisers lacked a V-twin engine. No surprise, they didn’t thrive, but soon enough, the Big Four had at least one cruiser with a V-twin engine.

The Very V-Twin First Metric Cruisers Introduced In America

• Yamaha Virago 750
• Honda V4 V65 Magna
• Yamaha Virago 920
• Kawasaki Vulcan 750

Vibrations That Don’t Rattle You But Bring Character

You may not like vibes on the handlebars, but there’s something about watching a big V-twin ratting around in a Harley frame. Here’s the thing: V-twin engines are massive, so much so, a liter-class cruiser is considered small or entry-level. These engines have big pieces moving around, and unlike other performance-oriented engines, the pistons aren’t small, the connecting rods aren’t paper thin, and the flywheels aren’t nonexistent. The big pistons move with a gusto in the cylinder. This is why V-twin cruisers throb as they lurch away from a stoplight.

In an engine, vibrations come from two sources: the inherent imbalance in the reciprocating parts (pistons) and the pulses descending from the ignition. This vibration is part of the design, present regardless of the power output.

Primary And Secondary Vibrations’ Contribution To Character

Enter primary vibrations, which are created by the acceleration and deceleration of the pistons. But to counteract this, most cruisers feature a 45-degree V-twin, where the vibrations are isolated to the vertical plane. Consider the Harley-Davidson configuration here; these cylinders are not offset from each other — they are in line. Such a vibration is easier to dampen. Simply lock the engine transversely and let it shake up and down as much as it wants.

Then come secondary vibrations, which occur twice the engine speed, and they act in the same plane as the primary imbalance. To overcome this, companies use various technologies, like counterbalancers, additional shafts, and drives in the crankcase. After that, companies tend to leave it to the rider to enjoy. The vibration is the heartbeat of the engine, and for long-stroke, low-revving motorcycles, it’s character.

Easier To Fit In The Frame While Adding Stability In A Straightline

Does a better V-configuration exist that doesn’t vibrate as much? Damn right, it does — Ducati calls it an L-twin engine, but it’s essentially a 90-degree V-twin. This configuration has inherently counteracting primary forces and minor secondary forces, so they are much smoother than narrow-angle V-twins. So, why don’t cruiser manufacturers use it?

A wide 90-degree V-twin is simply too difficult to fit in a motorcycle chassis. On the other hand, narrow-angle V-twins were naturally designed to fit into bicycle frames, and even when it comes to modern bike chassis, they fit much easier. The triangular shape seems molded to the available space between the front wheel and the swingarm, without hanging out of the bike like a transverse inline-four engine.

Such a configuration brings two more benefits to the bike’s handling dynamics. One, the narrow profile of the engine centralizes mass, giving the bike more stable handling. Yes, cruisers don’t handle so well, but now you know the engine is doing everything it can to make them handle better. The second is flexibility in terms of fore-aft weight distribution, which will make the bike more stable in a straight line.

Great American Cruisers For The Long Haul

Power? No, Torque Is King For V-Twins

You can extract more power from an engine in a few ways: put more air into the engine, add more compression, or increase the engine speed. But when it comes to cruiser bikes, there’s no replacement for displacement. This is because V-twin engines are long-stroke engines, which have a smaller bore.

Theoretically, smaller bores have a major issue — they leave less room for the valves — less air going into the engine. These engines turn asthmatic at high RPMs, but they breathe pretty well at low RPMs. So, long-stroke low-revving engines can do away with a simpler valve design, as they don’t need more than a single valve per cylinder. Since cruisers are designed for long hours on the highway in a lower RPM range, who needs all that complicated engine mechanics? Still, that hasn’t stopped manufacturers from making V-twin engines with four-valve designs, since they are more efficient at lower revs.

This is just one example of how V-twin engines for cruisers can get away with simpler mechanics without compromising on torque output. These engines also share an intake manifold and crank-pin, while generally featuring more simple internals. It’s no surprise that modern V-twin engines produce so much low-end torque despite having simpler designs. That’s what they’re made to do.

Harley-Davidson Sportster S Specifications

(Specs sourced from Harley-Davidson and Zeroto60times.com)

V-Twins Are Literally The Heart Of The Bike

Did you know that Harley-Davidson once wanted to trademark the signature potato-potato exhaust note? Sure, it was for a unique character, but it was also a way to protect other manufacturers from producing single-crankpin 45-degree V-twins. But there’s more to the V-twin rumble than that. Modern V-twins, in general, evoke a similar emotional response with distinctive sounds — it’s the idea that you get to hear the entire combustion process in slow-mo. Thank you, long-stroke pistons!

A big V-twin goes like this: bang-bang-pause-bang-bang-pause — this is a more natural-seeming rhythm than the regular frenzy of an inline-four screamer. For many, this potato-potato sound is like a heartbeat. Yes, the angle of the V-twin matters, but different V-twin engines sound more alike than different. These engines have a charisma that is unparalleled in the motorcycling world. If you’re going to spend weeks on the saddle, you might as well have a rumble of an exhaust note, right?