If you look at a four-stroke engine, there is a "bang" from a piston every 720º or every 2 revolutions of the crankshaft. In an 4 cylinder, engine, if you divide 720 by 4 you get 180º so evenly spaced piston firings would give you one bang every half turn of the crankshaft and this is exactly what an I4 engine does. An I4 is the type of engine which is in nearly all Jap sportsbikes except the SP1 and SP2 and TL1000.
Having bangs every 180º of crank rotation is really nice cause it gives you smooth power and that "screaming' noise all Jap sportsbikes make. However, once the rear tyre starts to spin, keeping it under control will tax even the most experienced riders- most of us will get a grandstand view as we highside the bike.
With a twin say like a Ducati which has a 90º V angle, the firing order of the bike is
bang (90º) bang (270º, 360º), repeat ad infintum or in laymans terms, bang-bang, pauuuuse, bang-bang pauuuuse, etc. When speeded up to 10,000RPM it sounds like a growl more than a scream.
The reason that this is interesting is that despite the power advantages that I4s have, many riders love the way the twins deliver their power and current thinking is that this is to do with the firing order which with the long 630º of crankshaft rotation before the next bang, gives the tyres a chance to regain grip when the rears are sliding.
When Ducati developed their Desmosedici GP bike, they used a V4 and had a choice of firing orders, either "Bing Bang" ie like a twin it all happens at once and then nothing for a long pause, etc or a more even firing order like an I4.
They ended up going for the even firing order to get more power and longevity and as everyone saw in 2003, the Ducatis had no shortage of power but keeping it under control was another issue. Suddenly, the Ducatis were screaming whilst the Hondas were growling.
In 2004 they decided to switch to the big-bang growler engine configuration and immediately the riders were happier with the power delivery even though it made slightly less power. However, tinkering with other parts of the bike screwed up other aspects of the bike. All of a sudden their bike growled not screamed.
Yamaha was unique in 2004 because they had a I4 engine, just like your R1 but they decided to do a big-bang engine on it and judging by the results, the gamble paid off (thanks in no small part to a certain racer). And the bike sounded like a Ducati. This is significant because conventional wisdom says to win in racing you need a V engine for exactly for the power delivery.
The main reason that the Japs love the I4s over the V engines is cost, less valvetrain, machining costs, complexity etc. Now Yamaha has proven that you can have the best of both worlds, V engine characteristics with the cost of an I4 without resorting to fancy traction-control shit.
Hence my comment about the likelihood of a Growler R1 although I suspect it might be a homologation special at first.
Last edited by MSS37; 03-03-2005 at 04:02 AM.