Reverse engineering for m/c head design

[drwebb]

I've got a Suzuki GS500 motorcycle, air cooled 2 cylinder DOHC shim on buckets operating 2 valves/cylinder. Not very high performance, but market longevity attests to it's design durability. I believe Suzuki originally produced a contemporary 1000 cc model with 4 valve head, but the 500 got 2 valves in keeping with its more utilitarian application. I wonder why they may not have chosen a single cam design at presumably lower parts count/cost?

 

[BrianPetersen]

Compare parts count:
DOHC: 2 camshafts, 2 cam sprockets, 4 buckets, 4 shims.

SOHC: 1 camshaft, 1 cam sprocket, 4 rocker arms, 4 rocker shafts, 4 screw/locknuts.

Not a whole lot different at the end of the day.

 

[dgallup]

If they already had the DOHC cam drive designed then design reuse saves making & testing new parts. Also, don't forget DOHC was probably a strong marketing buzz word back then.

 

[SomptingGuy]

Wasn't the GS1000 a DOHC 4-cylinder with 2 valves/cylinder?

- Steve

 

[BrianPetersen]

Suzuki built many engines both SOHC and DOHC. The GS1000 that I am thinking about, which was 1980-ish, was Suzuki's first (I think) production engine with DOHC and 4 valves per cylinder, and so-called TSCC (Twin Swirl Combustion Chamber).

Looking back from today, that bike seems like a lump, but it was as state-of-the-art in its day as the GSXR1000 was 20 years later.

 

[drwebb]

Thanks for the ideas folks- The design reuse explanation has an ironic appeal, because the daughter application has lasted 20 years- much longer than the parent! Sort of a case of the tail wagging the dog. . .