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Anyone rode a "Big Bang firing order" bike?

Discussion in 'Technical and Troubleshooting Torque' started by Fa1c0n, Jul 3, 2014.

  1. Anyone rode a "Big Bang firing order" bike?

    Just wondering about anyone who has had experience with a bike modified to be "Big Bang". What does it feel like? Does it improve performance? Whats the deal?

  2. I've only ever riden a factory Big Bang. They sound meatier, like a very twin, the real benefit of it is improved traction due to the gap in the firing interval.
  3. I suspect the purpose behind Yamaha going for it was for wsbk. No real purpose for standard road riding. Homologation rules require homologation stuff.
  4. They're OK in theory ....

  5. If you mean an R1 they aren't big bang, they're cross plane crank but that's not big bang...

    I did see a build once where a guy made a mid 90s blade big bang with a custom crank as they run wasted spark.

    Sounded awesome and seemed to perform well
  6. You mean a Laverda 180 triple ?
  7. The "better grip" myth is exactly that: a myth. I can't remember exactly where I found the info, but big bang results in less traction. Why else is it not used in moto gp? It was an experiment by some major manufacturers many years ago, but they realised that the theory was bollocks, and they abandoned it.

    All of that being said, cross-plane cranks and vee configuration don't necessarily mean big bang firing (which is all cylinders firing in one complete rotation of the crank - preferably all firing within 180 deg of crank rotation). The main advantage of cross-plane cranks and vee configuration is that there's always at least one (usually at least two) pistons that are in motion. This reduces the need for a flywheel, increasing the engine's ability to change RPM quickly, and increasing the acceleration for a given power/torque.

    Sorry to burst any bubbles...
    • Informative Informative x 1
  8. ^^ The YZR-M1 MotoGP bike is a cross-plane or 'uneven bang' engine ( firing intervals of 180-90-270-180 ) . By comparison , Kawasaki's ZX-RR MotoGP bike was a 'long bang' engine (firing intervals of 180-540) .

    The crossplane mimics the characteristics of a 90° V4 running a 180° crank but with the benefit of a more compact engine layout.

    The theory goes that the longer/uneven intervals between the firing pulses give the tyre time to regain traction when compared to the regular pulses from a traditional 'screamer' inline 4 . This was the reason that Honda developed the 'big bang' NSR500 in the early 90's and was subsequently copied by the other manufacturers.

    However in the current age of traction control it's rather a moot point.
  9. First of all I thought the NSR500 was the Ovel piston engine with 8 valves per cylinder, two spark plugs per cylinder and two conrods per cylinder. Kind of a cross between a V8 and a V4.

    Also being 2 stroke, each pair of psitons fire at 90 degrees and there is a 90 degree gap between each pair so the strokes are evenly spaced and it is a screamer enging, not a big bang engine.
  10. Except that it was a bastardised v4 rather than vtwin.
  11. Nah, that was the NR750, which allegedly stood for Never Ready!
    • Like Like x 1
  12. As @MV@MV said the oval piston bike was the NR500 which went on to become the NR750 endurance racer and ultimately spawned the NR750 road bike.

    Yes , you're partly right about the NSR500 being a 'screamer' - the early NSR's from 1984 to 1991 were indeed 'screamer's' with 90° firing intervals but in '92 they became 'big bang' before reverting back to 'screamer's' in '96 or '97 - which was mainly influenced by Doohan. See http://en.m.wikipedia.org/wiki/Honda_NSR500 and refer to the years 1990 - 1998 .

    Anyway , this has gotten way off topic - please continue .
  13. Re: V4 2-stroke big bang... The crank pins are offset. The big ends of the conrods of cylinders directly across the vee from each other may have rubbed against each other, but they were eccentric, not concentric. If Holden could do it in the old 3.8L V6 engines, then so could Honda in the NSR500.
  14. What difference, if any, would I notice if I converted my HD 1200Sportster to "Big bang" or is it already similar to that style firing?
  15. It's already similar to that firing style.
  16. Got it. Thanks.