Why SOHC?

[Athame57]

Having produced a range of DOHC in the 1960s why did Honda go back to SOHC like the CBs in the 1970s? It seems regressive unless I'm missing something.

[Johnwebley]

Having produced a range of DOHC in the 1960s why did Honda go back to SOHC like the CBs in the 1970s? It seems regressive unless I'm missing something.

I am guessing, simplicity

You notice how small and tidy the sohc head is


Compare the late 70s 750/900 dohc heads,much bulkier

Ok,I know about 4 valves etc,pent roof chambers, but these were only just arriving, as in the DFV,

but the RR Merlin was 4 valves, and pent roof if memory serves
That was late 1930s



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[Laverda Dave]

I think Honda only made the one DOHC road bike in the 60’s George and that was the CB450, all the remainder were sohc engines. The race bikes were DOHC but these were racing exotica made with equally exotic materials that were far to expensive to put into production as a road bike engine although a 250 six road bike in the 60’s (and the 70’s, 80’s and beyond) would have been the last word in showing off down the chip shop! Honda's mainstay engine in the 60’s and 70’s was the sohc. You also have to remember a sohc engine in the 60’s was also advanced for its time considering what the Brits were churning out, leaky OHV singles and parallel twins produced on clapped out pre-war machinery.

[McCabe-Thiele (Ted)]

I suspect the reason (on cars) was servicing costs for adjusting the valve clearances.
Much easier to adjust a rocker screw than mess with shims.

[Athame57]

I think Honda only made the one DOHC road bike in the 60’s George and that was the CB450

Hi Dave
The CB450 was the bike I was looking at on youtube ( via a link on here) and CMSL, I didn't realise it was the only one. The title of Black Bomber forum on here has a suffixed comment DOHCs only need apply... that seems to have misled me! 

[Athame57]

I suspect the reason (on cars) was servicing costs for adjusting the valve clearances.
Much easier to adjust a rocker screw than mess with shims.

Duuuhhh... what's a shim Ted? 

[florence]

I would imagine that SOHC was much cheaper to manufacture, more profitable, and good enough for what it was.

[Bryanj]

Dont forget this was the first PRODUCTION four cylinder and dohc would have been a lot more complication in the rush to get there first