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Old 3rd December 2007, 17:26   #1
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Default Firing order-Remixed comes to Bikes?

I rode a Yamaha 1400 V-4 Royal Star recently only to discover (to my dismay) that the firing sequence seemed to be designed to mimic the sound of a Harley. Phew. Remixed comes to Bikes??

To my mind, the ideal solution would have been evenly spaced firing intervals around 360 deg, which meant a 4-cyl job would yield one power pulse every 90 degrees to get the most out of those 4 pots in terms of smoothness among other things...correct me if I'm wrong.

Another way of looking at it- why have 4 pots if you're going to have 2 of them fire together?

Also read somewhere of racing boffs at HRc and Kwackers deciding between 'screamer' and 'growler' engines, based presumably around a similar approach t timing-management.

What say?
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Old 3rd December 2007, 21:45   #2
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It has an effect on torque delivery... growler engines have more torque at hand, lots of it, come in large pulses. Screamer has a smoother torque delivery.
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Old 4th December 2007, 14:05   #3
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Ah. Does that mean that auto engineering has come full circle? That the push for high-revving machines- with a naturally narrow power-band- is being revised towards slower-revving, torquier engines?

It somehow sticks in my craw that racing machines could run the lazy-dog engines of their cruiser counterparts...just can't imagine it.
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Old 4th December 2007, 14:32   #4
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Hmm... not exactly. Big bang engine sused in racing are not exactly lazy slow cruiser engines.

By having two cylinders firing at the same time doesnt mean the engine has to be slow revving.
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Old 4th December 2007, 16:19   #5
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I am wondering why i do not understand anything in this thread!! technical stuff..
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Old 4th December 2007, 16:43   #6
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Sankar- you got a point there.

Men_in_jean: :-)
I trip on quasi tech stuff as a facet to biking. But it needn't be everyone's cup of tea.
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Old 4th December 2007, 18:53   #7
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Quote:
Originally Posted by netchef View Post
I rode a Yamaha 1400 V-4 Royal Star recently only to discover (to my dismay) that the firing sequence seemed to be designed to mimic the sound of a Harley. Phew. Remixed comes to Bikes??
Which other bike in the Yamaha range uses this engine? And whats the firing sequence in that?
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Old 5th December 2007, 10:52   #8
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No clue, Spitfire. All I know is the Royal Star is a cruiser/street basher type of m/c, and she's naked. If I recall right, she was a shaftie.
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Old 6th December 2007, 09:44   #9
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I think all of us needn't throw in the towel yet for high revving engines. These types of firing sequences will be reserved for relaxed cruiser/street motorcycles wherein a large steady power/torque curve is desired rather than a peaky surge at very high revs. It all boils down to usabililty and customer preferences.I don't think track tools will be incorporating these kind of firing sequences any time soon.

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Old 6th December 2007, 12:34   #10
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Doomsday is right firing sequence is altered as per the purpose of the bike.
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Old 6th December 2007, 13:18   #11
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Most of the 990cc motogp bikes were running on the big bang configuration, except the kawasaki. These bikes were putting out a lot of power and the big bang motors helped a lot in preserving the tires and the thus the drive out of corners.

And most of the current 800cc motogp bikes have reverted back to the screamer configuration. Again except the Kawasaki.. kawasaki seems to do it opposite to what everbody else is doing.

The 2005 yamaha wsb bike also ran a big bang configuration.. but instead of firing two cylinders together it fired 1 cylinder first, then 2 cylinders together, and then the 4th cylinder.

Big bang was introduced during the mick doohan era by the honda to tame those fearsome 500cc two stroke motors. But then some others switched to the big bang config and the lap times were becoming stagnant and mighty mick went for a screamer config on the 500cc v4 two strokes and he was winning and lap times improved


Big bang is easy on the tires and on the riders.
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Old 7th December 2007, 10:44   #12
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Thanks for enlightening, chaps.
Talking of screamers, remember the Honda 125 x 5 and 250 x 6 cyl racers of the 60s? The bloody 125s wld rev to 22,000 RPM, and a pit joke went that they wld begin to misfire if so much as a cloud passed over the circuit. (I heard a Suzy GSXR600 sports-prepped m/c recently in the hands of a V Capable rider, and at 16K RPM, she was the most glorious thing I'd heard short of a Formula 1 car, so I can well imagine what the 60s Honda racers must have sounded like.
I remember Mick Doohan. Some of his vintage were awesome riders. Older gen too with names like Geoff Duke, M Hailwood etc. ..real men. Bikes with heaps of horses, but hardly much else in terms of suspension or brakes. They were tough. Kenny Roberts Sr who was not really vintage once said he wasn't paid enough to ride the 750 Yam 2 stroke he raced (no brakes to talk of).
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