I was looking in the Manufacturers manual for a marine Diesel twin cylinder
engine recently ( It was SABB. Not SAAB, SABB. I'd never heard of it before)

Anyway, it contained this gem.

Firing Order - 1,2.

Where would we be without the manuals?

Steve

shazzbat  wrote:


> I was looking in the Manufacturers manual for a marine Diesel twin cylinder
> engine recently ( It was SABB. Not SAAB, SABB. I'd never heard of it before)
> 
> Anyway, it contained this gem.
> 
> Firing Order - 1,2.
> 
> Where would we be without the manuals?


It's a perfectly valid point, though.

The order could be: 12, 12, 12, 12 IYSWIM
(ie. both cylinders firing together).

Could also be 2,1 - especially important to know if it has an uneven
firing cycle like my old bike did - 270 degree crank.

-- 
Steve H 'You're not a real petrolhead unless you've owned an Alfa Romeo'
http://www.italiancar.co.uk - Honda VFR800 - MZ ETZ300 - Alfa 75 TSpark
Alfa 156 2.0 TSpark Lusso - Passat 1.8 Turbo SE -  COSOC KOTL
BoTAFOT #87 - BoTAFOF #18 - MRO # - UKRMSBC #7 - Apostle #2 - YTC #

SteveH wrote:

>
> Could also be 2,1 - especially important to know if it has an uneven
> firing cycle like my old bike did - 270 degree crank.


Out of interest, any idea why a 270 degree crank would be preferable to 180? 
I think I'll have a Google...

Si

Andy Hewitt wrote:

> 
> Mungo "two sheds" Toadfoot  wrote:
> 
> > SteveH wrote:
> > >
> > > Could also be 2,1 - especially important to know if it has an uneven
> > > firing cycle like my old bike did - 270 degree crank.
> >
> > Out of interest, any idea why a 270 degree crank would be preferable to 180?
> > I think I'll have a Google...
> 
> Honda also uses a 360 cycle too - both pistons are in the same position,
> just one cycle apart.


That seems the most logical for a 2-cyl 4-stroke engine, it will probably
give the smoothest gait, assuming an inline engine.

Maybe his 270 degree crank belongs to a 90deg V engine?

Johannes  wrote:


> Andy Hewitt wrote:
> > 
> > Mungo "two sheds" Toadfoot  wrote:
> > 
> > > SteveH wrote:
> > > >
> > > > Could also be 2,1 - especially important to know if it has an uneven
> > > > firing cycle like my old bike did - 270 degree crank.
> > >
> > > Out of interest, any idea why a 270 degree crank would be preferable
> > > to 180? I think I'll have a Google...
> > 
> > Honda also uses a 360 cycle too - both pistons are in the same position,
> > just one cycle apart.
> 
> That seems the most logical for a 2-cyl 4-stroke engine, it will probably
> give the smoothest gait, assuming an inline engine.
> 
> Maybe his 270 degree crank belongs to a 90deg V engine?


The idea was to make a parallel twin feel and sound like a V-twin.

There's supposedly a traction advantage for a bike, in that there's 2
power pulses close together and then a gap to allow the rear tyre to
regain some grip, IYSWIM.
-- 
Steve H 'You're not a real petrolhead unless you've owned an Alfa Romeo'
http://www.italiancar.co.uk - Honda VFR800 - MZ ETZ300 - Alfa 75 TSpark
Alfa 156 2.0 TSpark Lusso - Passat 1.8 Turbo SE -  COSOC KOTL
BoTAFOT #87 - BoTAFOF #18 - MRO # - UKRMSBC #7 - Apostle #2 - YTC #

SteveH wrote:

> 
> Johannes  wrote:
> 
> > Andy Hewitt wrote:
> > >
> > > Mungo "two sheds" Toadfoot  wrote:
> > >
> > > > SteveH wrote:
> > > > >
> > > > > Could also be 2,1 - especially important to know if it has an uneven
> > > > > firing cycle like my old bike did - 270 degree crank.
> > > >
> > > > Out of interest, any idea why a 270 degree crank would be preferable
> > > > to 180? I think I'll have a Google...
> > >
> > > Honda also uses a 360 cycle too - both pistons are in the same position,
> > > just one cycle apart.
> >
> > That seems the most logical for a 2-cyl 4-stroke engine, it will probably
> > give the smoothest gait, assuming an inline engine.
> >
> > Maybe his 270 degree crank belongs to a 90deg V engine?
> 
> The idea was to make a parallel twin feel and sound like a V-twin.
> 
> There's supposedly a traction advantage for a bike, in that there's 2
> power pulses close together and then a gap to allow the rear tyre to
> regain some grip, IYSWIM.


I think it was quite common on British bikes to have identical firing
cycles on 2-cyl bikes, it gave the characteristic bike thumping sound.
Maybe is was to simplify the ignition mechanism or some other reason?
But it gave a lot of vibration of course.

"Johannes"  wrote in message
news:43231DCB.64DD76A8@spam-gets-banned-sizefitter.com...

>
>
> SteveH wrote:
> >
> > Johannes  wrote:
> >
> > > Andy Hewitt wrote:
> > > >
> > > > Mungo "two sheds" Toadfoot  wrote:
> > > >
> > > > > SteveH wrote:
> > > > > >
> > > > > > Could also be 2,1 -


Unlikely

especially important to know if it has an uneven

> > > > > > firing cycle like my old bike did - 270 degree crank.
> > > > >
> > > > > Out of interest, any idea why a 270 degree crank would be
preferable
> > > > > to 180? I think I'll have a Google...
> > > >
> > > > Honda also uses a 360 cycle too - both pistons are in the same
position,
> > > > just one cycle apart.
> > >
> > > That seems the most logical for a 2-cyl 4-stroke engine, it will
probably
> > > give the smoothest gait, assuming an inline engine.
> > >
> > > Maybe his 270 degree crank belongs to a 90deg V engine?
> >
> > The idea was to make a parallel twin feel and sound like a V-twin.
> >
> > There's supposedly a traction advantage for a bike, in that there's 2
> > power pulses close together and then a gap to allow the rear tyre to
> > regain some grip, IYSWIM.
>
> I think it was quite common on British bikes to have identical firing
> cycles on 2-cyl bikes, it gave the characteristic bike thumping sound.
> Maybe is was to simplify the ignition mechanism or some other reason?
> But it gave a lot of vibration of course.


I don't think it was. Every (twin) Brit bike I had anything to do with had
one up one down.

Steve

shazzbat  wrote:


> > I think it was quite common on British bikes to have identical firing
> > cycles on 2-cyl bikes, it gave the characteristic bike thumping sound.
> > Maybe is was to simplify the ignition mechanism or some other reason?
> > But it gave a lot of vibration of course.
> 
> I don't think it was. Every (twin) Brit bike I had anything to do with had
> one up one down.


Are you sure about that? - it was the Japs who did the 180 degree firing
cycle - old Brit. bikes were famous for firing both pistons at the same
time.
-- 
Steve H 'You're not a real petrolhead unless you've owned an Alfa Romeo'
http://www.italiancar.co.uk - Honda VFR800 - MZ ETZ300 - Alfa 75 TSpark
Alfa 156 2.0 TSpark Lusso - Passat 1.8 Turbo SE -  COSOC KOTL
BoTAFOT #87 - BoTAFOF #18 - MRO # - UKRMSBC #7 - Apostle #2 - YTC #

"SteveH"  wrote in message
news:1h2otj4.7oirruo4pkn5N%steve@italiancar.co.uk...

> shazzbat  wrote:
>
> > > I think it was quite common on British bikes to have identical firing
> > > cycles on 2-cyl bikes, it gave the characteristic bike thumping sound.
> > > Maybe is was to simplify the ignition mechanism or some other reason?
> > > But it gave a lot of vibration of course.
> >
> > I don't think it was. Every (twin) Brit bike I had anything to do with
had
> > one up one down.
>
> Are you sure about that? - it was the Japs who did the 180 degree firing
> cycle - old Brit. bikes were famous for firing both pistons at the same
> time.
> --

I'll give you that, I tangled myself up there :-))

Steve

"shazzbat"  wrote in message 
news:dfucqv$j5u$1@news7.svr.pol.co.uk...

>I was looking in the Manufacturers manual for a marine Diesel twin cylinder
> engine recently ( It was SABB. Not SAAB, SABB. I'd never heard of it 
> before)
>
> Anyway, it contained this gem.
>
> Firing Order - 1,2.
>
> Where would we be without the manuals?
>
> Steve
>


 That is there to stop you firing it up in reverse.... ;-)

On Sat, 10 Sep 2005 14:47:55 +0100, Andy Hewitt wrote:


> Mungo "two sheds" Toadfoot  wrote:
> 
>> SteveH wrote:
>>>
>>> Could also be 2,1 - especially important to know if it has an uneven
>>> firing cycle like my old bike did - 270 degree crank.
>> 
>> Out of interest, any idea why a 270 degree crank would be preferable to 180?
>> I think I'll have a Google...
> 
> Honda also uses a 360 cycle too - both pistons are in the same position,
> just one cycle apart.


Smooth power delivery but a horrible thing to balance. Suzuki tend to have
them 180 degrees out - easy to balance but lumpy power delivery from idle.
I've ridden both and prefer the Suzuki - much more smooth at speed.

On Sat, 10 Sep 2005 19:17:21 +0100, SteveH wrote:


> shazzbat  wrote:
> 
>>> I think it was quite common on British bikes to have identical firing
>>> cycles on 2-cyl bikes, it gave the characteristic bike thumping sound.
>>> Maybe is was to simplify the ignition mechanism or some other reason?
>>> But it gave a lot of vibration of course.
>> 
>> I don't think it was. Every (twin) Brit bike I had anything to do with had
>> one up one down.
> 
> Are you sure about that? - it was the Japs who did the 180 degree firing
> cycle - old Brit. bikes were famous for firing both pistons at the same
> time.


My father's Triumphs, (Bonneville and Speed Twin) fired alternatly but the
pistons rose and fell together.

Chris Street  wrote:

<Snipped Text>


> > Honda also uses a 360 cycle too - both pistons are in the same position,
> > just one cycle apart.
> 
> Smooth power delivery but a horrible thing to balance. Suzuki tend to have
> them 180 degrees out - easy to balance but lumpy power delivery from idle.
> I've ridden both and prefer the Suzuki - much more smooth at speed.


I've only ever ridden a CB400N twin, and I honestly couldn't remember
what layout that was. It was a rough old thing anyway.

The one's I have in mind are indeed used in cars, they were fitted in
the old N and Z model Hondas of the 70's, both as 360cc air cooled and a
600cc liquid cooled versions. It was also used in the Acty vans too.
They were quite smooth, and only used a single carb, so balancing wasn't
a problem. Not bad performance either, the Acty vans could top 80mph.

-- 
Andy Hewitt **  FAF#1, (Ex-OSOS#5) - FJ1200 ABS
Honda Civic: Windows free zone (Mac G5 Dual Processor)
http://mysite.wanadoo-members.co.uk/thehewitts2/index.htm
(updated Aug 28 2005)