Hmm... I would have thought that the SMAX would have nearly the same fuel economy
as the PCX. And I too have read about the 63 mph top speed of the PCX 150 and find it
just a bit disconcerting that Honda has no explanation as to why. If it is indeed speed
limited, then simply disconnecting the speed sensor should probably fix that. But my
suspicions of limiting speed by electronic means seems to be confirmed by what I have
found.
But doing some digging I found an aftermarket electronic gizmo that allows a higher
rpm. (up to 11,000 rpm depending on what other performance equipment is in use.)
(exhaust systems) Which is apparently higher than the stock 9,800 rpm limit.
http://japan.webike.net/products/21552398.html
Looking at the info on the KITACO i-map injection controller, I see the 9,800 rpm
mentioned. This also probably requires some tinkering using the hook up to a computer
to update the original map or settings can be altered by dip switches. Really, it seems
very much like a Power Commander III injection controller like there is for the Honda
Silverwing scooter. (other makes and models of motorcycles too)
The PCX 150 doesn't have a tachometer that would show it hitting its rpm limit and from
most accounts, corresponds to the best speed it can apparently do at that rpm limit.
So the gizmo would let it creep up a little higher in speed and may actually let it get to
about 70 mph or so.
The thing is that there is a warning of possible "valve surging". Looking up this term as
it relates to engines, I find terms like "spring surge" and "valve jump" I get an inkling of
what that means; in a nutshell; it sounds like the valves are loosing the ability to keep up
with the speed of the cam. Anyway, they say back off and don't do that.
Don't know that spending a little over $95 plus shipping from Japan would be worth the
approximate 7 mph gain in speed though. (and the possibility of grenading the engine)