Technical question: screamer vs. big bang

There has been much discussion lately about screamer and big bang engines. I wonder, does all that apply just to 4-cylinder engines? Must a 2-cylinder/3-cylinder/5-cylinder engine be a screamer then? In example, what engine did the Honda RC211V (5-cylinder 990cc) have? Thank you and sorry for my ignorance.

Pardon the brevity - it's 5 in the ^&$%^ morning and Q is running.





BB is about the crank angle between the pistons/cylinders. It can apply to any multi-piston engine.



The idea is that as one (set of ) piston(s) is slowing at TDC or BDC, the other(s) are zipping along at maximum linear velocity. This allows the two (pair) of piston(s) to exchange inertia torque pulses, rather than send the 'noise' out of the engine and to the tire.



A straight triple would have 120 degrees of crank throw between the big end bearings.

A 4 is 90 degrees, a straight 5 would be 72, and a BB CBX would be 60 degrees. parallel twins are back at 90, while the rods of a 90 degree Vee-twin can share a single journal.

good explanation



changing the firing order to big bang is making the intervals between the ignitions longer and therefor the firing order irregular.can be applied to any engine with more than one cylinder ,even a two cylinder can be set to fire both pistons at the same time.





uneven/long firing intervals means you increase friction which means you sacrafice a bit of power but on the other hand it's more rider friendly because it makes it easier for the rider to apply the throttle as early and hard as possible





not a expert on the v5 .....sorry

One of the better on-line explanations.

http://www.ashonbike...oss-plane_crank



Inertia torque pulses occur at a very high frequency, but the effect is somewhat similar to rapidly twisting the throttle back and forth - the positive and negative torque pulses make smooth, predictable traction difficult to achieve.

From an earlier post: "[font="tahoma, arial, verdana, sans-serif"]It's all about a characteristic called inertia torque. This torque is caused when the con rods and pistons come to a halt at top and bottom dead center. Each time a piston slow to a stop, it transfers its momentum (inertia energy) to the crank, causing it to spin slightly faster. Then the crank then has to pull on the piston to start it moving again. This causes the crank to slow down a little. On a classic straight 4, all the pistons are coming to a halt at the same time, producing notable pulses of positive and negative energy (rotational speed) in the drive system. This irregularity rises rapidly with RPM; kinetic energy goes up with the square of linear velocity, so the faster the pistons are travelling, the more energy is required to start and stop them. When the torque pulses get strong enough, they can travel down the drivetrain and into the tire, producing irregular traction and sketchy feedback. On a crossplane I4 (or properly timed V engine), one bank of pistons is coming to a halt as an other is accelerating, This allows the inertial energy to be exchanger between piston pairs, so very little of it escapes the engine."

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