Friday, November 25, 2022

The magic of Royal Enfield's 'thump'

 Nothing is more important to a Royal Enfield motorcycle than the sound it makes. The Royal Enfield Bullet is renowned in India for its "thump." This low, slow pulse of sound results from the big single-cylinder motor's relatively slow heartbeat. 

The "thump" is as important to Royal Enfield as the "potato-potato" sound of a V-twin is to Harley-Davidson. 

Modern Royal Enfield motorcycles, even Royal Enfield's new twin-cylinder models, seek to preserve something of the mellow mumble of the thump. Being loud isn't the goal. You want rhythm, not percussion. (For example, watch this YouTube clip of the sound made by the new Royal Enfield Hunter 350.)

My own Royal Enfield, an old 1999 Bullet 500 with an after-market (louder) muffler, is not very mellow. For one thing, I won't risk lowering the idle speed until you can count the power strokes. I don't want to risk stalling. 

Besides, there's a better way to get that melodious sound. 

The fastest, cheapest and easiest method to improve the exhaust note of an old Royal Enfield motorcycle is to insert foam earplugs into your ears.

The effect is magical. The clatter of push rods goes away but the gentle rhythm of the motor comes through.

I believe I've found an endorsement for this in the oddest place: a 1920 article by "Ixion" in The Motor Cycle magazine. 

Cover of book "Xion of The Motor Cycle."
Dave Masters' book "Ixion of the Motor Cycle."

Ixion was the pseudonym of Basil H. Davies, an Anglican priest and avid motorcyclist who from 1903-1961 wrote a sort of diary of his observations awheel for the magazine.

He did not fear to give offense by creating noise.

"On my way home recently, for example, I negotiated no fewer than 11 absolutely blind corners. On roads of such a character noise is the only valid insurance, " he wrote in 1920.

"It is good for me to make as much noise as I can, and if I meet another fellow near any of these corners, I prefer his machine to be as noisy as possible."

But here is the key: He also writes: "I have not the least wish to ride a noisy machine where noise is useless."

It might be well here to note that, in Greek mythology, "Ixion" was a man Zeus punished by binding him for all time to a fiery wheel. That was torture. Ixion, the gentle priest and magazine columnist, would not choose to be tortured by noise.

A motorcycle should be "Free from mechanical noise at all times. My present mount makes a moderate noise at all times; and 50 per cent of its noise is mechanical noise. Wherefore from my standpoint it is just about as bad as a machine can be," he wrote.

He envies a neighbor's Indian, "which on small throttle openings creates no sound beyond the mild swish of well-lubricated chains."

That's it!

It's mechanical noise that bugs people. Ixion wants others to hear the trumpet of his motorcycle, but doesn't want to hear the percussion himself. Thus, take my advice. Pop in the earplugs, banish the jackhammering sound of the push rods, and all that remains inside your helmet is music to the ears.

Ixion's hope that noise is a safeguard around blind corners has something of the "Loud Valves Save Lives" joke about old Royal Enfields. It's amusing but it's just a joke. At any good rate of speed you're leaving most of the noise behind you, doing nothing to wake up the drivers ahead, who are the threat.

Of course, things may have been different on Ixion's 1920 rides around his country parish.

"If and when the powers that be compel us all to ride machines which are dead silent I shall emigrate," he wrote. I wonder what he would think of the coming age of (silent) electric motorcycles?

I found the excerpt from Ixion's article on noise in the 1920 section of the Motorcycle Timeline blog.

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