My two stroke twins have all been 180 cranks,
since a two stroke fires every
revolution, would just be two singles if
they wer a 360 crank (Ossa's 500
was a 360 crank, but I never rode one of
those).
Honda's CA 72/77 Dreams, and the 125/150 Benlys were 360 crank,
single carb
bikes for sure, and I think that the 1968 - 1976 CB 350/360s,
CB/CL
were..but I would have to look that up. I think, also from memory,
that the
CB 160/175s, Twin Stars (ugh), Rebels and Nighthawk 250s were
also 360
cranks.
Honda's CB 72/77 Hawk/Super Hawk were 180 cranks
as were the original DOHC
CB 450s. I had a newer 450 Hawk..the 3 valve per
cylinder SOHC thing, which
I think had a 360 (ugly appliance looking
engine, unlike the original 450
which had one of the best looking
motorcycle engines ever in my opinion).
180s for a small "revver" 4 stroke
seems appropriate to me.
Yamaha's XS 650 came with a 360, but there is
an an Australian made 270
crank that is getting a lot of attention on
their site. Supposed to be
smoother, better power delivery..never rode one
with that crank though.
James Franklin
2411 Pine Summit DR.
E
Jacksonville, Florida 32211
808-225-0994 (cell)
From: "Jonhaddock@..." <jonhaddock@...>
Reply-To:
W650riders@...
To:
<W650riders@...>
Subject:
Re: [W650riders] Re: bring back the w650 to the us - Petition
Date: Sat, 7
Jul 2007 10:34:21 +0100
I like the power delivery of a 360 degree twin.
Firing order is important.
The reason that Triumphs made such good dirt
bikes is that the firing angle
is symmetrical...every 180 degrees. Bang
chuff bang chuff and so on. Thus
you get a regular bang on every
revolution, at the same place...just like a
two stroke
single....
180 degree crank bikes don't have the same firing,...they're
either bang
chuff, chuff bang, or bang bang chuff chuff. It feels
different and not
entirely 'right' to me.
It's like the difference
between a 120 degree triple and a typical four. The
Triple always has a
totally different feel...somehow more appropriate to a
motorcycle...It
might be something to do with the regularity of power pulses
when the bike
is at the limit of traction...I don't really know, but
certainly 360
degree twin dirt bikes put power down in a very controlled
way.
Four stroke single dirt bikes are better than two stroke
singles at getting
power down initially as they punch out of corners and
that is entirely down
to the fact that the bikes composure has time to
settle in-between pulses
and the regular rhythm of the pulses allows the
rider to 'sense' the rear
tyre's behaviour . 360 twins are the same but
you need long stroke lower
revving motors to ensure the pulses are far
enough apart.
If they could make them light enough, I would not be
surprised to see four
stroke 360 degree twins competing again in top level
MX because they make
more power than a single with similar bottom end
grunt.
As you say, you need to add 1000 rpm to everything...That
doesn't work
'off-road' and the edge of that difference is what I sense
'on-road'.
I've no doubt your bike fuels smoothly, revs higher, makes
more power and
all that, but all 180 degree motors 'feel' slightly wrong
to
me...irrespective of build or brand.
Jon
----- Original
Message -----
From: Dennis J. Guggemos
To: W650riders@...
Sent:
Friday, July 06, 2007 7:22 PM
Subject: Re: [W650riders] Re: bring back the
w650 to the us - Petition
This I take issue with. The 650Rs power
delivery is one reason I bought
it. Feels like 2 singles grunting out of a
corner. Rarely do I take it to
8500 RPM (max hp). Usually it's ridden like
the W, just add 1000 rpm to
everything.
You need to ride one before
you flag it with the generalizations. It's
not a buzzy
ER5.
Dennis
----- Original Message -----
From: Jonhaddock@...
To: W650riders@...
Sent:
Friday, July 06, 2007 3:55 AM
Subject: Re: [W650riders] Re: bring back the
w650 to the us - Petition
In my opinion there is no comparison between
the two types of layout in
'feel' terms. Having ridden the old ER5 180
twin, it's 'just' a bike.
Fairly
peppy, of course, a bit revvy, nice
neutral handling and all that, but
no
magic to the power delivery or
feel.
.
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