Multis vs V-twins

[dipshit]

Honda CBR600:
42.5mm stroke
15,000 rpm redline
average piston speed = 2 x 15,000 x 42.5mm / 60 seconds = 21.25 metres per second

Ducati 1098:
64.7mm stroke
10,700 rpm redline
average piston speed = 2 x 10,700 x 64.7mm / 60 seconds = 23.08 metres per second

Even the SV1000 with its 66mm stroke and 1100 rpm redline ends up at around 24 metres per second.

Just another reason i prefer to short shift with the peak torque around 8000 rpm even when going for it. Not much point taking it out to the redline.

[slofox]

SV650 tops out at 22.9m/s @ 11000rpm.........but there's little reason to take it to redline - shift up at 10000 not 11000 since there's not much grunt there anyway....peak torque at 7000, peak power at 9000.....brings max linear piston speed to 20.87 m/s..........

[rocketman1]

Put it this way, If motorbikes where electric and had no sound,
what a BORE, I really don't think I would ride a bike.
The best pleasures of owing a bike is the sound of bike under full acceleration or slowing down.
That is more than half the enjoyment of the ride, figure it out.
Imagine a Harley that sounded like an electric toothbrush...get a life.
The sound of SV1000 with two Yoshis screaming is bloody fantastic and makes life and riding a bike, what its all about, pure magic.
Say what you like V twins RULE.
Like you, I have listened to them all ...go figure, end of argument..

[Dazza]

Put it this way, If motorbikes where electric and had no sound,
what a BORE, I really don't think I would ride a bike.
The best pleasures of owing a bike is the sound of bike under full acceleration or slowing down.
That is more than half the enjoyment of the ride, figure it out.
Imagine a Harley that sounded like an electric toothbrush...get a life.
The sound of SV1000 with two Yoshis screaming is bloody fantastic and makes life and riding a bike, what its all about, pure magic.
Say what you like V twins RULE.
Like you, I have listened to them all ...go figure, end of argument..

Well said,except the bit about the SV (P/T)

[slofox]

Put it this way, If motorbikes where electric and had no sound,
what a BORE, I really don't think I would ride a bike.
The best pleasures of owing a bike is the sound of bike under full acceleration or slowing down.
That is more than half the enjoyment of the ride, figure it out.
Imagine a Harley that sounded like an electric toothbrush...get a life.
The sound of SV1000 with two Yoshis screaming is bloody fantastic and makes life and riding a bike, what its all about, pure magic.
Say what you like V twins RULE.
Like you, I have listened to them all ...go figure, end of argument..

Whilst I do agree with your point, I would be quite interested to ride a silent bike - once anyway....just to experience it......wind noise only...hmmmmm.
But as far as V-twins go, you are right on the hammer......nothing quite like that snarl as they power up through the revs.......hurhurhur.....

[Dazza]

Whilst I do agree with your point, I would be quite interested to ride a silent bike - once anyway....just to experience it......wind noise only...hmmmmm.
But as far as V-twins go, you are right on the hammer......nothing quite like that snarl as they power up through the revs.......hurhurhur.....

I had a wee issue with the Akrapovic Y pipe on my previous Super Duke & refitted the original cans (first time ever running them) for 5000k's, after running race cans for 30000k's & I really enjoyed the noise (lack of), especially the trip to the Brass Monkey & back last year. But once they where refitted I'm all for race cans (have Evo Akrapovics on the new one), make the most of them whilst it's still legal

[Dooly]

I have a vtwin, inline 3 & inline 4.
I find the 4 the smoothest, the twin vibrates of course especially down low.
IMO opinion my 3 cyl Speed Triple is the pick of them, good torque down low, plus power all thru the range including up top like a 4, but the best sounding, the twin, especially with the carbon cans on!!!!!

[2wheeldrifter]

Quote:
Originally Posted by Forest
I love v-twins. They're slim, torquey, and light.

However I do worry a little bit about linear piston speeds in high-performance V-twins.

What is linear piston speed?

Who cares just ride the freckin thing!! Looking at forest's avatar he needs to grow up lol

[johan]

Quote:
Originally Posted by Forest
I love v-twins. They're slim, torquey, and light.

However I do worry a little bit about linear piston speeds in high-performance V-twins.



Who cares just ride the freckin thing!! Looking at forest's avatar he needs to grow up lol

ya mate, I take my 998 to the track every month and ride it like I stole it. It lives between 6000-10500 RPMs most of the time so I'm trying to understand how this will affect the engine.

Last time we pulled it apart things were still looking good.

I'll continue to abuse it till it falls apart. By that time I'll hopefully have sponsors queued up to give me two 1098R to race

[sinned]

What about the triples? Sheesh!

Wide Open Throttle on the S3 in a tunnel/underpass is pure porn.

[Winston001]

....basically in a large-capacity v-twin engine the pistons have to move further than in other multi-cylinder engine configurations.

Unfortunately there are physical engineering limits on the maximum linear speed that a piston can travel. If you exceed these limits, the oil isn't able to keep the engine lubricated and the cylinder bores start to wear out.

The high-performance large-capacity v-twins used in modern sports bikes like Ducatis, Aprilias, and KTMs are running very close to the engineering limits for linear piston speed. .

But isn't that why water-cooling is used in the superbike V-twins? To allow finer tolerances and control metal expansion/contraction?

I'm grateful to you Forest for the calculations because its pretty sobering stuff to pause and think about the forces at work in a high-performance motorcycle engine. A large piston hurled down and then forced up, only to come to a sudden stop, all at around 20m/sec - lots of kinetic energy. Its amazing these things go for tens of thousands of km.

[Forest]

But isn't that why water-cooling is used in the superbike V-twins? To allow finer tolerances and control metal expansion/contraction?

I'm grateful to you Forest for the calculations because its pretty sobering stuff to pause and think about the forces at work in a high-performance motorcycle engine. A large piston hurled down and then forced up, only to come to a sudden stop, all at around 20m/sec - lots of kinetic energy. Its amazing these things go for tens of thousands of km.

Yep. It is incredible that they work as well as they do.

The amazing thing is that in a high-performance v-twin engine the average piston speed is 23-25 m/s but the peak piston speed is around 200km/h.

In a 1098 engine at full tilt (10,700 rpm) each piston gets accelerated to 200km/h and stopped again around 356 times a second.