firing sequences on parralell twins

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

 

that would be more like a fish out of water

ck

 

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

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).

 

??
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.

 

Oh no, not this trawling again.

GB

 

Oops.

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

 

haha

 

Maybe a bit like riding a big two-stroke single.

Remeber that a four stroke cycle takes 720 degrees.
The cylinders only fire every second revolution, so you get nice, evenly
spaced firings.

Cyl 1 -Suck- squeeze *BANG* -blow- -Suck- squeeze *BANG* -blow-
Cyl 2 *BANG* -blow- -Suck- squeeze *BANG* -blow- -Suck- squeeze


If the cylinders were 180 out of phase, you would get

Cyl 1 -Suck- squeeze *BANG* -blow- -Suck- squeeze *BANG* -blow-
Cyl 2 -blow- -Suck- squeeze *BANG* -blow- -Suck- squeeze *BANG*

Moike

 

Who are you replying to?

 

Re: Who am i replying to...



....

<snip>

It's 1, 2


Conehead
Happy to help
================

 

corks.... mate..... my opinions are my own - get fucked - get your
own~

however, as you asked nicely... 360 degre throw on the crank doesn't
mean both pistons fire at the same time. the japs used the 180 degree
throw on their twins to help eliminate the vibes that the british
twins suffered.

yeh, 270 degrees does make for a nice note

johno
ps... all capitals were left out so corks could read this

 

its that from left to right or right to left ?

 

corks... you being in the west, it is right to left...


Johno

**** you corks - if i offered you a Coopers, you wouldn't appreciate
it~~ ;P

 

cooopers , dark ale from memeory , hell yes i'd drink and appreciate you for
giving it to me

 

ThAnK YoU VeRy MuCh FoR yOuR kInD WoRdS aNd SeNSiBlE AnSwer

 

Every man's dream: twins.

GB

 

Geeze, c.dean, can't you get anything wrong.

You are supposed to tell Smee he's just an anal lazy prick who likes a
nice lean desktop, and thinks others should waste bandith telling him
what he just read.

Tell him to bugger off and feed the kid.

(gotta get the domestic credits up for wintersun, eh!)

Moike

(oh, shit, is it beer o'clock already?.. gotta run.)

 

Geeze, c.dean, can't you get anything right?

You are supposed to tell Smee he's just an anal lazy prick who likes a
nice lean desktop, and thinks others should waste bandith telling him
what he just read.

Tell him to bugger off and feed the kid.

(gotta get the domestic credits up for wintersun, eh!)

Moike

(oh, shit, is it beer o'clock already?.. gotta run.)

 

Wintersun is a remote possibilty atm.
Rugrat is acting like a baby.

 

Corks... I'm not sure Johno was real clear... with a 360 degree twin
both pistons go up and down at the same time, but they fire alternatly.

This doesn't actually feel exactly like a big single, but it does have a
large vertical component to the vibration so the vibes are mostly up and
down similar to a single.

Hard to explain... but it is different to a single.


G-S