Newsgroups: rec.motorcycles
Subject: Re: Harley Outperforms ZX11, Film at Eleven
From: zeleny@husc10.harvard.edu (Michael Zeleny)
Date: 13 Oct 92 11:06:09 EDT
Organization: The Phallogocentric Cabal

In article <1992Oct13.020852.7884@tcsi.com> 
markk@tcs.com (Mark Kromer) writes:

>zeleny@husc10 (Michael Zeleny) writes:

MZ:
>>In this respect, Harley engines
>>suffer from a disadvantage shared by Ducati and Vincent (which managed to
>>log on 100,000 street miles in early Fifties), of forcing two connecting
>>rods to share a single crankpin.  

MK:
>There is nothing wrong with putting two rods on one crankpin.  It is
>common practice in V-engines and is responsible for the compactness
>and light weight of V configurations.

In principle, it is better to have one bearing per journal, not in the
least because of the need to manage the thrust loads that would be
inevitably generated otherwise.

MZ:
>>As for the general merits and shortcomings of the latter, there remains a
>>lot to be said for the aesthetics of its engine design, the needless
>>complexity of the valve train notwithstanding (a rockerless DOHC design
>>simply cannot be beat from this standpoint).  

MK:
>DOHC is not the be-all and end-all of cylinder heads.  For a V-twin
>engine you would have four camshafts and two independant cam drive
>systems for two cylinders.  This is obscenely complex and would only
>be considered where valve float (or the need for a marketing buzzword
>like DOHC) becomes the limiting factor in the design.  It is
>excessivly heavy and requires larger, taller, and heavier cylinder
>heads.  It requires pressureized oil feed to the heads.  It is likely
>to require more difficult maintainence, more complex and expensive
>replacement parts, and be less realiable than a push rod design.

Nonsense.  The pushrod valve actuation system is far more complicated than
the rockerless DOHC variety.  Count the number of the moving parts, if you
are in doubt.  As for the need for pressurized oil feed to the heads, it is
always a good idea to have it, if only for the sake of the rocker arms.  If
your concern is with top-end weight, look at motocross engines, which by
and large have abandoned the weight-saving SOHC configuration.  The fact of
the matter is, pushrods set an inherent limitation on engine speed by
introducing extra slop and flexibility.  Look at the BOTT race class, the
last one where pushrod engines still compete with overhead camshaft
designs, and see what the added expense of racing the former is, in terms
of extracting the greatest performance out of an engine.

MK:
>Pushrods are actually an excellent design given the Harleys relatively
>low red line.  Harley isn't faced with any displacement limitations.
>If more power is desired, they can just punch the motor out a little
>more rather than trying to squeeze more power out of a smaller motor.
>Why screw up an effective design?

Due to their long stroke, for Harley engines, piston speed is a far greater
limitation than valve actuation rate.  Which just goes to show that they
are not built for power.  Still, it is a damn shame that their design puts
such prohibitive limitations on any possibility of sporting use.

MZ:
>>Alas, all this is compromised
>>by the factory's insistence on saddling it with a twin monstrosity of a
>>bulky clutch and wide drive belt, thereby severely limiting both the
>>potential ground clearance and footpeg placement, as well as the rear tire
>>width.  Furthermore, none of the Harley frames, much less the rest of their
>>chassis components, are adequate, either in material or design, to the
>>levels of horsepower and torque which can be readily obtained by tuning
>>their engines.  

MK:
>ground clearance?  rear tire width?  sport riders?
>Harley does not build sportbikes.  Period.  It's like complaining that
>your Hemi Cuda won't pull 1.3 lateral G's.  That's not what it's for!

Well, too bad for them then.  I think a manufacturer ought to adapt to the
demands of the market, not the other way around.  As evidenced by the
number of people still trying to race their agrarian machinery, Harley
loses a lot of customers by not building sport bikes.  I think even the
factory has come to recognize this by instituting the 883 racing class, and
making a lot of noise concerning their perennial race bike development
efforts.

MZ:
>>Thus, any sport rider whose first priority is handling and
>>control, is automatically excluded from the Harley club.  

MK:
>I don't get it.  If you don't like the bikes Harley builds why would
>you want to be in the "Harley club"?

Indeed, you don't get it.  I do like the bikes Harley builds.  Alas, their
deficiencies as sporting vehicles surely outweigh all their attraction as
studly propulsion devices from the standpoint of this rider.  As much as I
resent the disposable commodity aspect of Japanese machinery, I cannot see
the stodgy American product as a viable alternative.  So I ride Ducatis and
Laverdas.

>--
>)V(ark)<               markk@tcs.com                   DoD #400
>1988 FZR400            1985 ZX900 Ninja             1977 RD400D
>"I'm sorry sir, your artillery shell is no longer valid.  Coat, tie
>and Motor Home required for admission to The Club."

cordially,
mikhail zeleny@husc.harvard.edu
"Nous donnons la mort, nous saurons la subir."

Newsgroups: rec.motorcycles