Movement of both pistons.

[Joule]

So i have noticed that most four cylinder bikes have two pistons moving together at 180 degree to rest two.
R1 has crossplane crankshaft with each piston at 90 degree.
More of a buzzing sound :P

So i was wondering what kind of movement Ninja's engine has?

my guess is that both pistons move together because it does sound like a single cylinder bike >_>

anyone ? :P

[Racer x]

The pistons of the 250 ninja are 180 deg apart. Meaning one is up when one is down. Triumph Norton and other twins have both pistons going up and down together.

The 180 deg crank with counter balance shaft is good to 15000 rpm

[Joule]

Originally Posted by Racer x

The pistons of the 250 ninja are 180 deg apart. Meaning one is up when one is down. Triumph Norton and other twins have both pistons going up and down together.

The 180 deg crank with counter balance shaft is good to 15000 rpm

Thank you racerX !

but then how does bikes like cbr 1000 with two pistons moving at 180 degree have a buzzing exhaust note?
While r1 with crossplane crankshaft sounds much like our ninja 250r? XD

what's the factor deciding the exhaust note? ( it's obviously not the exhaust )

http://www.youtube.com/watch?v=HNiFfvH-xQc

Edit: exhaust gases are supposed to escape with less interval in r1. but cbr still sounds better in "buzzing" sound?

[Racer x]

I believe and am probable wrong. The cross plain crank from Yamaha is a big bang engine. I can't remember how it works but the power pulse of the engine is more like a twin. This is better than the rapid power hits of the Honda because it allows the rear tire to relax and regrip the track. My guess is it sounds like a twin. But I am guessing.

[choneofakind]

The new R1 sounds more like a big twin than an inline 4.

Example of how the bike sounds:

Link to original page on YouTube.

For comparison, here's an inline 4 without the cross-plane crankshaft:

Link to original page on YouTube.

Here's an explanation of how the engine works:

Link to original page on YouTube.

I hope that helps a little bit. It made sense to me, but since I couldn't find a similar video for an inline 4 without a cross-plane crankshaft, I'm a little fuzzy on the firing pattern of a typical inline 4.

[Joule]

I know that :P

Here's what i want to know.

Imagine ~

a single cylinder makes 2 revolutions per second. ( just imagine XD ) it's gonna obviously sound like a thumper. because exhaust gases will escape two times per second.

Now, our ninja 250r has two cylinders with one piston up and other down.
It's gonna sound much better than a thumper and exhaust gases will escape 4 times per second. because of two pistons NOT moving together.

Thirdly, r1 with crossplane crankshaft and uneven firing sequence is supposed to sound like a screamer because exhaust gases will escape 8 times with 2 revolutions of crankshaft per second ( remember not to act a geek because we are just assuming :P ) But as we all saw r1 sounds like a twin? duh ~? Almost same sound as ninja

Then comes cbr 1000 or any other inline 4 ( gixxer,hayabusa,ninja,etc )
They have two pistons upwards and 2 downwards. meaning two pistons move together. okay i just observed that 1 piston is fired at a time. that's 8 times exhaust gas escaping per 2 revolutions of crankshaft and they sound .. like a screamer? buzzing sound which i LOVE ~



and according to exhaust gases escape frequency, r1 should be making buzzing sound. not sound like a twin -...-

none of this **** makes sense LOL

[Joule]

I edited my above post.
I just found out that despite two pistons moving together in typical inline 4, only one piston is fired while other one is going through it's 3rd stroke.

haha ~ Found it O_O

[Whiskey]

Exhaust note also has to do with the length of the exhaust's path through the system, how the acoustics work through joints (4-2-1, 4-2-2 or straight through) ect.
Posted via Mobile Device

[Motofool]

Originally Posted by Joule

a single cylinder makes 2 revolutions per second. ( just imagine XD ) it's gonna obviously sound like a thumper. because exhaust gases will escape two times per second.

Four stroke engines complete a thermodynamic cycle every two revolutions; hence, one exhaust stroke per second would be correct.

Check this animation:

http://www.animatedengines.com/otto.html

[Joule]

Originally Posted by Motofool

Four stroke engines complete a thermodynamic cycle every two revolutions; hence, one exhaust stroke per second would be correct.

Check this animation:

http://www.animatedengines.com/otto.html

Thanks but this much i know. I just took 2 revolutions randomly. that's 4 for 2 stroke.

[greg737]

Now, our ninja 250r has two cylinders with one piston up and other down.
It's gonna sound much better than a thumper and exhaust gases will escape 4 times per second. because of two pistons NOT moving together.

The parallel twin two cylinder engine with a flat plane crankshaft does sound better than a thumper, but not by much. This is because the two cylinders fire just 180 degrees apart and then there's nothing for the remaining 540 degrees of rotation in each 4-stroke cycle. Gives it a lopsided sounding idle.

That's why its sound seems to have more in common with a thumper exhaust note than anything else.

[dirty nasty]

I think the 250 sounds like a thumper below 7 grand. Above that it sounds better. At high RPMs I think it sounds okay. Surely not even close to the best, but I've heard many worse bikes. I say the best sounding bike is the one you can't hear.

[alex.s]

Originally Posted by Racer x

The pistons of the 250 ninja are 180 deg apart. Meaning one is up when one is down. Triumph Norton and other twins have both pistons going up and down together.

The 180 deg crank with counter balance shaft is good to 15000 rpm

whats holding the n250 back to 13000ish outside of ignition? the valve train?

[EvilPooMonkey]

Originally Posted by dirty nasty

I think the 250 sounds like a thumper below 7 grand. Above that it sounds better. At high RPMs I think it sounds okay. Surely not even close to the best, but I've heard many worse bikes. I say the best sounding bike is the one you can't hear.

i actually agree with that a lot. i do a lot of low rpm ridingon my daily commutes and i think thats one reason i fell in love with the jixxer. i can get around town and parking lots without the annoying scream i usually get in first. it may be petty but it is one of the things that i value :P

[lgk]

I wonder how yamaha torque pulse compares to a v4 design. Seems like it could be similar.

[choneofakind]

Originally Posted by alex.s

whats holding the n250 back to 13000ish outside of ignition? the valve train?

I'm pretty sure that's it. That's what I get from reading at least. When talking about the adjustable rev-limiter on their BRT thing, Sportisi said the valve train is good to 16k, buuut I wouldn't push it too far if you don't want to do damage...

My pregen goes to 14500 without issue yet, so you're good to at least there I would assume.

[alex.s]

Hmmmmm....... i think some investigooshon is needed. TO THE CAT MOBILE!