2 vs. 4 cylinder sportbikes

[Mintbread]

I know that they had a displacement advantage but I am neglecting to mention that.....ooops! Did I say that out loud????

Which is the only reason Ducati is on the racing map.

I have owned a VTR100 and a TL1000 and happen to love big twins but to say that they are better for the twisties than an inline four is completely wrong.

[ZooTech]

I...happen to love big twins but to say that they are better for the twisties than an inline four is completely wrong.

Based on what logic? The narrower engine allows more lean angle and the v-twin torque allows the rider to power out of the turns quicker. Fours are by no means slow, and nobody is making that claim, but they do have laughable torque numbers and you can't run 15,000 RPM's through a turn. If a 4-cylinder engine was the only formula that worked for racing, nobody in their right mind would be riding twins. It depends on the particular race course and the ratio of turns to straights. I, too, have owned an inline four and two twins, and after riding the dragon in Tennessee I'm here to tell ya a screaming 4-cylinder will do you no good on that road.

[Mintbread]

Lets discuss this again the day a twin wins a world championship with the same displacement as the fours.

And regarding "screaming 4-cylinders" on twisty roads, I ride a 1200 Bandit that pushes out a few less horsepower but exactly the same torque as litre twins, so it is more than capable of holding its own before during and after a corner.

[kabob983]

So the low-RPM torque is where the advantage is for the twins, exactly how is that (still new to the designs of motorcycles). What allows the 2 cylinders to pump faster at low RPM's than 4? How much larger are the cylinders in a V-Twin than in a 4 cylinder bike?

Good info so far, thanks guys!

[Mintbread]

Bigger bangs.

[kabob983]

Per stroke? Is that basically just from bigger cylinders?

[TechTMW]

Bigger bangs.

To put it bluntly, yes heheh Think about it, if you have a 1000cc inline 4, each cylinder displaces 250cc. In A 1000cc twin, each cyl displaces 500cc. The torque is not a matter of pumping faster, it's more a matter of How much force the piston has when it moves down in the cylinder. If you compress 250cc worht of air and fuel and ignite it, the piston will push down with less force than a piston being driven by 500cc of compressed air and fuel.

The biggest factors when determining how FAST an engine will rev are Bora nd Stroke. Bore is how wide the piston is, Stroke is how far the piston travels from Top Dead Center to Bottom dead center.

A bike with more bore than stroke (it's wider than the distance it travels up and down) is called OVERSQUARE. Typical Race Replica bikes, like a GSX-R have Oversquare engines. This allows for High revving capabilities, as the piston has a short distance to travel.

A bike with more Stroke than Bore is called UNDERSQUARE. Harley is a good example of an Undersquare engine. (So are diesels) The piston has a long way to travel, so it can't rev as fast.

Keep in mind these are BASIC principles. Many other factors apply, such as the length of intake runners, piston shapes, valvetrain characteristics, etc. With modern technology it is easier to overcome the deficiencies inherent in each design, although generally the above remains true.

The whole 2 vs 4 thing is really a moot point anyway, unless you are planning on being a racer. Mint on his Bandit may very well be able to dust someone on a Ducati 999 in "spirited street riding" The bandit's engine is an Oversquare engine that has had some of its characteristics tweaked to be able to pump out more torque in the low and middle ranges (Compared to a GSX-R 1000 for example.)

I will agree that European bikes are over priced compared to Japanese. Blame it on economics or whatever. They are just for a different breed of biker (as are Harleys.)

[kabob983]

Thanks Tech, that explains alot.

European bikes are quite overpriced, not that I'm looking to spend that on a first bike anyways though...it'll hopefully be a used bike in decent condition for $1500 or less...

[High_Side]

Which is the only reason Ducati is on the racing map.

Er, how about the last two outta three moto-gp races then?????

And now to point out the logic flaws on the other side of the argument.....

Based on what logic? I, too, have owned an inline four and two twins, and after riding the dragon in Tennessee I'm here to tell ya a screaming 4-cylinder will do you no good on that road.

Er, how about the GSX-R 1000????? Do you THINK it might have trouble keeping up with the average twin down that road??????

I love argueing both sides

[kabob983]

I love argueing both sides

You're just so devious