Quote:
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Originally Posted by chinarider
Isn't the overhead cam a better engine than the pushrod-OHV?
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Certainly that's what Car&Driver magazine has been saying for the last 40 years!
In general, at a given
power output the OHV will be:
>greater displacement
>physically smaller and lighter
>less expensive to build
So if you have some restriction on displacement, such as in certain racing classes or in some countries that tax and/or license based on displacement, the OHC has definite advantages. Otherwise, say if you're just riding around on streets and trails in the USA, the OHV design has some strengths that can't be overlooked.
Now, concerning these particular engines: they decend from the Honda vertical, air cooled single cylinder OHC design of the mid- to late 1960s. It was a fine little design, with a single weakness: top end oiling. In the early 1970s
Honda came out with a more robust OHV version of these engines that they still build to this day. The little CG125 that uses the OHV even got a mention in Honda's latest annual financial report as a model with strong and increasing sales, and all of Honda's utility ATV models use OHV engines.
tcs
PS - Did you know?: OHV Chevrolet Corvette racers have beat DOHC Porsches and Ferraris at the famous 24 Hours of Le Mans 6 of the last 8 years.
PPS - OHV in other motorcycles:
BMW: the "R" series twins are OHV.
Harley-Davidson: all bikes but the VROD are OHV.
Kawasaki: the flagship Vulcan 2000 has an OHV.
Moto Guzzi: OHV throughout their model range.
Royal Enfield: their OHV 350cc engine was produced from 1947 until 2008, making it the longest production life motorcycle engine of all time.
Yamaha: the flagship Star Stratoliner has an OHV engine.