Motorcycle Sounds

Deryle Mehrten

 

The sound a motorcycle makes is not limited to the exhaust.  The valves seating, the gears whining, cam chains whistling, there's a lot of different "instruments" that contribute to the total sound of a motorcycle engine in motion.  Though the R-Bike is BMW's trademark, I prefer their fours, the K-Bikes.  I like the sounds they make when coming up on the cam.  It's my kind of music.

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An Orchestra in Motion: This last month Wanda and I went to the PITS rally up in Heber.  We met/re-met some terrific folks and had a great time.

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I had a very interesting conversation with one particular gentleman I met about how a motorcycle is like an orchestra.  The better in tune the orchestra the better the music.  The better in tune the motorcycle the better the music as well.  Ever hear a vintage bike on the pipe, in full song (the British like to say at full chat)?  The bike is singing to you.

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It wasn't too many years back that I was into making heavy modifications to the bikes I owned.  Trick exhausts, carburetors, cams, all the hot stuff to make the bike go faster.  I never really thought of the bike as an orchestra.  I made changes to the horn section (the carburetors) and didn't change the percussion section (exhaust) to match.  The notes the individual parts were playing didn't come together as a melody; rather they came together as a cacophony.  The orchestra was out of tune.  I got a lesson in how to tune high performance engines from Ohya-san, "If you change one thing, it will affect all things."  Pretty heady stuff when all I wanted to do was go faster.

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So now along comes the modern bike, computer designed, and computer run.  These machines are so highly controlled by electronic circuits, it is amazing.  The exact time to open the injectors, the exact amount of air/gas mixture, the exact time to spark, and it goes on.  They are like Moog synthesizers.  They play electronically controlled music.  The orchestra will be in tune, the computer will see to that.  But whose tune?

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I have been told manufacturers, in order to meet EPA/DOT requirements, set their bikes' electronic brains to be pretty lean in the low to middle rpms.  That is where the EPA/DOT inspectors take their readings.  So now I have a bike that has been programmed to be out of tune.  The song the bike will sing at those rpms will not be pleasing to the ear. 

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Along comes the tuner of the 21st Century.  I was taught that the points gap on a BSA could be set with a cigarette paper.  The tuner of the 21st Century is taught how to run Windows and brings along a laptop.  They plug their laptop into the bike's brain and teach the bike new tunes.  What a concept. 

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Some electronic brains can be changed quite a bit.  Others don't give the electronic tuner much to work with.  The aftermarket is busy backwards engineering the electronic brains on many bikes.  You can install a new brain, and your bike will sing a different tune.  If you don't like that tune, program in another.  I wonder how a bike would run on the Beatles' Yellow Submarine?

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The last three bikes I have bought I haven't changed anything in the engine or engine-management department.  "Box Stock" is my motto.  The electronic controlled music sounds just fine.  I'm pretty much deaf in the right ear anyway.  Deryle and Wanda Mehrten, riding our orchestra in motion.  mehrten@cox.net

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Deryle & Wanda Mehrten

Sierra Vista AZ USA