firing sequences on parralell twins

[corks]

just curious as to waht the most common or the "best" firing sequence for
p-2's

i would have thought 1 up - 1 down (180 degree crank) would have ben most
common

but notice the new triumph are 360 degree cranks - both pistons firing at
once, wouldnt this been ling riding a big single ???

tho i notice the triumph america and speedmaster use a 270 degree crank -
same as my trx850 , presumably to get that v-twin note???

any opinions

dc

[ck]

Post by corks
but notice the new triumph are 360 degree cranks - both pistons firing at
once, wouldnt this been ling riding a big single ???

that would be more like a fish out of water

ck

[GB]

Post by ck

firing at once, wouldnt this been ling riding a big single ???

that would be more like a fish out of water

Oh no, not this trawling again.

GB

[l***@gmail.com]

Post by corks
just curious as to waht the most common or the "best" firing sequence for
p-2's
i would have thought 1 up - 1 down (180 degree crank) would have ben most
common

Tis what the Japs (and others) use because it normally requires no
counterballance shaft.

Post by corks
but notice the new triumph are 360 degree cranks - both pistons firing at
once, wouldnt this been ling riding a big single ???

They don't fire at once, they are still alternate firings, just the
pistons travel up and down at the same time (i.e one is on the power
stroke while the other is intake etc).

Post by corks
tho i notice the triumph america and speedmaster use a 270 degree crank -
same as my trx850 , presumably to get that v-twin note???

Yes.

Post by corks
any opinions

[c***@student.unsw.edu.au]

??
Most new triumphs are running three cylinder engines. The exceptions
are: Speed Four (four cyl) and Speedmaster/America (270degree crank
twins)
180 degree crank twins are far and away the most common parallel twin
cylinder arrangement.
270deg parallel twins are identical to 90degree V-twins in the sense
that their cycles interact in exactly the same way, ie: one cylinder
fires, ~270deg crank rotation interval, other cylinder fires, ~450deg
interval and repeat.

270 degree parallel twins:
Good: Sound nice, package well whilst sounding nice, alleged traction
benefits. Only one cylinder head required. Excellent example of how
cool these engines can be is the legendary TRX850.
Bad: Extra weight has to be added to the crankshaft arrangement in
order to balance it. With a 90deg V-twin, the crankshaft is naturally
balanced (180degree crank). Note that by '90deg' V-twin I am referring
to the 'Vee angle', not crank geometry or firing intervals.

Post by corks
just curious as to waht the most common or the "best" firing sequence for
p-2's
i would have thought 1 up - 1 down (180 degree crank) would have ben most
common
but notice the new triumph are 360 degree cranks - both pistons firing at
once, wouldnt this been ling riding a big single ???
tho i notice the triumph america and speedmaster use a 270 degree crank -
same as my trx850 , presumably to get that v-twin note???
any opinions
dc

[c***@student.unsw.edu.au]

Oops.

I just remembered something about those Triumph neo-bonnies having a
360deg crank......
Bracing myself for an avalanche of scathing replies.

[Pisshead Pete]

Post by c***@student.unsw.edu.au
Oops.
I just remembered something about those Triumph neo-bonnies having a
360deg crank......
Bracing myself for an avalanche of scathing replies.

...and you meant 90 degree 'L' twin!