MOTOGP » Kawasaki tests screamer, talks pneumatic

MOTOGP » Kawasaki tests screamer, talks pneumatic

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Kawasaki tests screamer, talks pneumatic

Here:

Kawasaki tests screamer, talks pneumatic

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4 agree. 2 disagree.

Screamer = lots of little bangs (say 4 in a 360' crank cycle)), Big Bang = less bangs but the bang is way bigger (like 2 in a 180' crank cycle)

Imagine a 4cyl motor, a screamer fires all cylnders evenly accross the crankshaft (4cyl roadbikes)
Imagine a 4cyl motor, A big bang fires 2 cylinders close together, turns the crank 180' and fires the other 2 cylinders close together. Kinda like a Ducati L2 but with a 4cyl where 2cyl are pair'd to act like 1....1 big one
Its said a screamer aplys constant drive to the wheels, a big bang provides a longer rest period between pulses and that is easier on tyres, wheel spin is easier to control and corner drive is less violent.....in a nut shell

Posted by Ace27 . (673 days ago)

Kawasaki's MotoGP test team ran a new even-firing 'screamer' engine during the final day of testing at Sepang.

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Yeah had put the low end bit in then deleted it as was getting too long....but yeah that is one thing that is attracting me to the new 1098S at the mo.
I've only ever owned jap bikes so im in for a change and slightly less hp also appeals to me, I get a kick out of beating bigger bikes.

Posted by Ace27 . (671 days ago)

Ace, The GSXR's are all standard 4-cyl with 1,3,4,2. They could be 1,2,4,3 which is less nice if you have 1,2 and 3,4 running in one exhaust. But anything else is quite "impossible".

The only bike you can buy with "BB" is the DUC-990 Desmo16 (twin pulse).

The cranks of the GP 4-stroke in line 4's are "shifted BB",so they emulate more or less the firing sequence of a Harley V-twin, so two quick fires and then a lot of time nothing(simply put)

As you fill basically "at the same time" 2 cylinders with "BB", it has a different performance curve with more low-end Torque. A "SCR" is much more powerfull at high engine speed as its cylinders are filled one after the other efficiently.

Posted by Harryx - Unregistered (671 days ago)

1 agrees.

Timing a engine is at the outer edge of my abillity, right now my ZXR750R race bike is apart, it shows 1342 fireing order, I bet my gsxr1000 is diferent (its much newer)
As I understand it the fireing order is designed to be 1. be even on the crank to keep vibrations down. The more vibs the less longevity, 2. and provide efficiency (crank rotational force efficiency).
Smoother? yes, liken a screamer to any 4cyl road bike, where as a BB is more like a L2 Ducati motor, big vibs, needs big counter balancers . (A 90' 2cyl motor is an L2[Ducati] A 60' 2cyl motor is a V2,[Harley]).

Posted by Ace27 . (672 days ago)

Ace with the screamer and big banger the crankcase,barrel/s valve gear are the same but the crank shaft and cams are different with a screamer what would be a normal timing be Eg 1'3'2'4 or 1'3'4'2 or what,,, is the screamer a smoother bike to ride I don't mean at race speed or excessive compression????

Posted by Saltbush - Unregistered (672 days ago)

Yes, but not precisly simultainious, a few degree's apart, cams run off the crank (cam chain/belt), crank design determins when pistons are at top dead center(TDC) so to build a BB 2 out of 4 pistons must be cranked a few degrees apart.
Sure its possible to use an ecu to change timing but to go from a dedicated screamer to a dedicated big bang crank loebs and cam loebs need altering.

Posted by Ace27 . (672 days ago)

With the big bang do you have 2 pistons on the firing/power stroke at the same time???
I would have thought with a different firing stroke for a screamer you would at least have to change the cam shaft timing????? I wonder if any of the bike manufacturers have looked at the old Offenhauser motor for a different type of Desmodromic valve control these motors could rev to 20,000RPM or has Ducati covered all types of Desmodromic valve set up???? I don't believe Offenhauser/Meyer Drake had a patent.The Offenhauser motors were monobloc so there was no separate head on less thing to blow a gasket.

Posted by Saltbush - Unregistered (672 days ago)

I had you picked for a moaner MM .

Joking ok ..

Cheers.

Posted by Rob Wilson (672 days ago)

I could make a joke about a big bang M M but that's too easy...

Posted by The Morgue (672 days ago)

You don't need to change crank to run BB.(1+4,2+3) or SCR.(1,3,4,2) unless you want to optimise the firing to spread a 2-cyl BB. event over let's say 50 °CA.

What you must do is change the camshaft for which on the intake and exhaust the cams for 2 cylinders (1 and 3 or 4 and 2) need to be advanced over one engine revolution( half a cam rev).What Morque said is possible in theory by an actuator. The ignition, controlled by an ECU, could adjust at the same time. You'd be running one revolution empty, so you would only be able to switch between BB. and SCR. in an overrun.

I think all the 990's were BB's at the end (even Kawa worked on it). Duc called it twin pulse.(really rough

)

Posted by Harryx - Unregistered (672 days ago)

1 agrees.

Abstract US Patent 7063059
A multi-cylinder four-stroke internal combustion engine enabling a method for on-the-fly switching between two or more firing orders. Switching to the new firing order is done without requiring any tear-down of the engine such as to swap camshafts. Switching can be triggered by the rider, or it can be triggered automatically per conditions such as selected gear, RPM range, track location, velocity, and the like.

Posted by The Morgue (672 days ago)

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