Motorcycle Forum / General / Sportbikes / February 2005

floor. they would both be without oil pressure. both would be factory
stock, same model year. If one bike had a higher compression ratio,
that would come into play, so remove the spark plugs to eliminate
compression.  This would eliminate a lot of variables, but still, one
crank with the TQ wrench still doesnt simulate opperating conditions,
so still would not get you accurate information that
you could use for anything.

An engineer in a lab would conduct bearing friction tests with simple
engineering models where a shaft riding in a lubricated main bearing
set or rod bearing set was driven at various RPM's by an electric
motor...

The model would be hooked to a small dyno and he'd get his horsepower
requirements for one bearing and then multiply the results for however
many bearings his real engine needed...

The power required to turn a camshaft and operate a valve train has
been measured in this manner. It took something like 3 to 5 horsepower
to operate the valve train in a small block Chevy V8, as I recall...

He would do something similar with a single cylinder version of his
multi-cylinder engine to measure friction losses from the piston rings
riding up and down the cylinder bores...

Honda developed their GP engines in the 1960's using single-cylinder
"mule" engines. They tried various experiments until they achieved the
Brake Mean Effective Pressure they wanted from one cylinder, and built
multi-cylinder engines (up to 6-cylinders)based on the mule's
characteristics...

(Of course, engines built from engineering lab models don't always
behave *exactly* as the engineer claims they should, and that's when an
engineer has to quickly come up with an explanation about why the first
actual engine built to his recommendations didn't perform to
expectations...)

To determine the operating friction of actual entire existing engine
and tranny combos, you could run both engines up to operating
temperature, then pull the spark plugs and turn them over with another
internal combustion engine on a dyno. Removing the plugs would
eliminate most of the pumping losses of the engines, especially that
part caused by intaking, compressing, and exhausting air. Something
like 1/3rd of the horsepower generated by an engine is consumed by
pumping losses...

But, who's going to do that, as long as there are other dessicated
subjects to be debated on AMS? As Jack Handey said, "There is nothing
sadder than a mosquito sucking on a mummy."

And typically limited to less than that to suit the rider's
preference.

But irrelevant of how much power is being made have you tried this
experiment on equivalently powerful motors in V4 and I4
configurations?

Or is *your* lack of research showing again?

Impossible, for some variation of what they consider acceptable I'm
sure.

I note you still haven't belt driven Mr. RC45 despite constant threats
to do so. And if you did you'd find out what others already have who
tried it with a VFR750 and a Speed Triple. Too much power, belt snaps
around 5-6k miles without warning. Hell even the Buell XB12 has had
complaints about that sort of thing. It seems there's only so much
juice Gates can handle before it goes ballistic.

So when Honda's engineers said no to belt drive they maybe meant it
wouldn't be reliable enough for the Honda nameplate. After all,
sticking one on your particular model and babying it like you take
care of all your machinery is not indicative of anything really. Try
it amongst hundreds of test mules and the results might be less
spectacular. Honda's resources are much deeper and their concerns far
more varied than those of an enthusiast tinkerer. Therefore it follows
their answers will be significantly different than your own.