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gttjohn
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953 Posts
Discussion Starter #1
bit of a thick question but i always wanted to know does the skyline 6cyl engine bang two pistons then two then two if so does all 6cyl engins do this and does the evo 4cyl bang one or two and the scooby bang two also do you guys know what i mean.
 

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Taking control of the drum machine
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835 Posts
2 pistons rise together, but each are on an opposite phase, so while one is compressing (squeezing) the air/fuel mixture, the other is blowing out the exhaust out.

Most 'even fire' engines (pretty much most modern engines) do this. And most
pair the piston from the outside, in.

The inline 6 (ours) would have 1&6 paired, 2&5 and 3&4, each pair set at 120 degrees on the crank.

The Evo is inline 4 - like virtually all 4 cylinder engines. Again, are paired 1&4 and 2&3.

The Scooby lump is different being a flat 4, the pistons on these don't pair up as such. The pistons on these are on there side instead of pointing upwards and split into 2 banks (say East and West). On each bank, the pistons move the opposite direction (one in, one out) - like a boxer punching (hence the nick-name 'boxer engine')
Iirc, the front 2 pistons (so front East and front West) both move outward or inward together and likewise the rear 2.


The idea for 2 pistons to move together is for balance and smoothness.
For balance, it keeps the crank even while turning (so both ends at any event, are evenly weighted)
Smoothness, only one is cylinder is fired, giving every time a piston goes up a firing event. So you get 6 firing events on a complete cam rotation instead of 3 bursts of power and 3 dead spots (it is VERY lumpy like this. An example is an old motorbike that used this method, created lots of torque on firing event, but was countered by then trying to compress 2 cylinders worth on compression stroke. So rode like a jack-hammer!)



Any use/clearer?
 

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gttjohn
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953 Posts
Discussion Starter #3
thank you very much my friend the reason i asked this question is because i seen an rb head stripped from the barrells and noticed that two pistons where up at the same time together then that got me thinking whell maby they suck, squeeze,bang and exhaust together in rows of two ,then i got to thinking about scoobs and evos.you have made it crystal clear to me thank you once again.
 
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Guest
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if you look at moto gp or the very new 2009 r1 this has the big bang engine which is 2 pistons firing together.

1&3 fire the 2&4 or even the honda moto gp bike which is a V5 but big bang dont ask fire order I do not know.
 

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gttjohn
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953 Posts
Discussion Starter #5 (Edited)
ill search that up now dann.............. right just searched that very interesting on the new yamaha r1 i dont like the sound of it but ide say its quick,thanks lads
 

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Taking control of the drum machine
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835 Posts
if you look at moto gp or the very new 2009 r1 this has the big bang engine which is 2 pistons firing together.

1&3 fire the 2&4 or even the honda moto gp bike which is a V5 but big bang dont ask fire order I do not know.
I guess its power over comfort on these things.
 

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gttjohn
Joined
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953 Posts
Discussion Starter #8 (Edited)
theres another cool idea ,in the honda motorbike engines theres cam gear train instead of cam belts no wonder you see a lot of guys couriering them they never brake down .i had a cbr 250 and it was bulit proof my brother had a vfr400 and that was bullitproof our friend had a gsxr it wasnt so robust
 
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