• Motorcycle engines are the hearts of the bike.

• Not all engines look alike and a few are truly beautiful.

• They not only belong to legendary bikes but they made the bikes legends.

Yes, the engine is the heart of the motorcycle. But while non-bikers are confused by how a lump of metal could do stir up so much emotions in us, to us they’re mechanical porn. Here are the best-looking motorcycle engines, in no particular order.

1. AJS 7R

The AJS 7R was a 350cc race bike built from 1948 to 1963. Commonly known as the “Boy Racer,” it won victories for both the factory and privateers from its inception.

Designed by Phil Walker, the single overhead camshaft (SOHC) was driven by a chain from the outside of the engine block, hence the “tower cover.” That cover and cylinder head cover were painted gold contrasting against the gray and black parts of the engine.

2. HRD Vincent Black Shadow/Black Lightning

The 1948 HRD Vincent Black Lightning was the race bike spawned from the Black Shadow.

It was the fastest production bike of its time, and widely acknowledged as the first superbike.

The Black Lightning was stripped down and its 998cc, air-cooled, pushrod, overhead valve (OHV), 47.5-degree V-Twin on the Black Lightning had stronger connecting rods, larger intake ports, polished rocker gear, steel idler gears, racing carbs and manual-advance magneto, pushing it to a top speed of 240 km/h.

Yes, yes, 240 km/h is attainable by most middleweight bike these days, but look at those skinny tyres the Vincent rolled on!

In September 1948, Rollie Free attempted to break US national motorcycle speed record at the Bonneville Salt Flats. He could only reach 239.1 km/h during practice so he stripped down to his swimming shorts, rubber cap and sneakers for the final run and hit an average of 241.905 km/h (regulations required two runs). That bike became known as the “Bathing Suit Bike.”

But it’s the level of attentiveness to detail and quality that made Vincents’ engines true works of art. Sadly, it was that kind of passion which made them time- and cost-consuming to produce.

Only 31 Black Lightnings were ever built.

3. Britten V1000

Frustrated with the lack of parts and reliability of stock engines, New Zealander John Britten decided to do the impossible: Building his own bike and engine.

Working from his home shed with a few buddies, he came up with a creation in 1991 that not only looks radical, but went on to dominate the Battle of the Twins championship over the factory bikes.

John Britten passed away in 1995 and only ten plus the one initial bike were made.

4. Ducati Singles

Fabio Taglioni adapted the desmodromic valve drive to Ducatis to combat valve float (the valves staying open, thereby causing loss of compression and peak performance) at high RPM. To turn the camshaft, a vertical shaft (also called a tower shaft) on the right side of the engine sent drive up to the camshaft’s idler gears through a bevel gear.

The resulting engine design together with typical Italian attention was the purest testament in the “form follows function” sense, and the “Desmo” became the trademark of Ducati.

5. Kawasaki W650/W800

The bevel gear lives! Well, for a while.

Ducati’s bevel drive was soon replaced by belt and finally chain drive in the interest of simplicity and weight savings, which saw the disappearance of the tower shaft and knuckle-like bevel gear cover next to the cylinder block.

But hang on, here comes the retro Kawasaki W650 and the later W800. Such beautiful bikes deserve beautiful engines, don’t they?

Then Kawasaki announced earlier this year that the W800 will be discontinued as will not meet future emissions requirements!

NOOOO!!!

6. Honda CBX

Speaking of Kawasaki, the 1978 Honda CBX was Honda’s weapon in the titanic arms race between the two Japanese companies. Honda’s wants to reclaim the world’s fastest production bike crown which it lost to the Kawasaki Z1.

Featuring a 105 bhp, 1047cc, air-cooled, DOHC, 24-valve, inline-Six, with six carburetors, it hit a top speed 216 km/h. But that’s just part of the story. The 1979 CBX blew through the ¼-mile run in 11.36 seconds, at 189.82 km/h.

The engine looks large and ungainly in the bike, but it’s only big at the top. The lower parts of the engine were made narrower but moving the alternator and final drive away to other locations to provide more ground clearance for spirited cornerning.

7. Moto Guzzi V-Twin

There’s no mistaking the Moto Guzzi V-Twin, with both cylinders sticking out the side. This transverse mounting uses the airflow to help cool cylinders and their alloy rocker covers, learned from aircraft experience, instead of having both cylinders stuffed longitudinally along the frame.

The deep, finned oil sump design has also survived to this day.

The newer engines such as the 843cc unit powering the V9 series and 744cc unit powering the V7 series are now fully Euro4 compliant, and are much smoother and easier to live with.

8. Triumph Twin

Whether in pre-unit form or the later iterations, Edward Turner’s created an icon. From the timing cases to the angular cylinder and finning around the cylinder block, the Triumph Twin is a distinctively beautiful power unit.

The essential design has been carried forward to the current crop of Triumph modern classics, never losing its trademark and appeal in spite of liquid-cooling.

9. Harley-Davidson V-Twin

How does one argue with something that has become an icon over so many decades?

Sure, one could argue that there isn’t much innovation or substantial power gain in the Motor Company’s V-Twins, but that’s not the point.

In any way you look at it, H-D’s 45-degree V-Twins (both the Big Twin and Sportster Evolution) form the focal point of all Harleys (except for the V-Rod) and that’s why so many customizers still prefer the Harley V-Twin (along with the aftermarket engines from S&S) as the starting point of their creations.

10. Suzuki “Square Four”

The Suzuki RG500 “Gamma” was built between 1985 and 1987, directly inspired by the RGB500 Grand Prix machine which won 7 consecutive constructors titles in the 500cc class with riders such as Barry Sheene.

The 498cc, liquid-cooled, two-stroke, twin-crank, rotary valved, four-cylinder engine had its cylinders arranged in a square configuration, hence the common pet name of “Square Four.” All four cylinders were arranged on the same plane in the earlier versions, while the later versions saw the front two and rear two staggered for better placement in the frame and weight distribution.

It was also the last 500cc two-stroke race replica ever built (the Bimota V-Due didn’t work).

And no, the pistons are not square-shaped.