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Discussion Starter #1
Anyone know where to find info on the firing pattern for modern inline-4's? I was trying to explain it to some one but couldn't do it justice and I don't know the crank pin position. It's gotta be like 90 degrees or less right? Anyone know or have a link to any information about the Big Bang firing pattern?

-Shrub
 

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Discussion Starter #2
This is all I could find so far. It doesn't really explain it in terms of modern 4-strokes though. The only other things I could find were stuff on Rossi going back to that pattern for traction control.

http://www.superbikeplanet.com/nsr500mat.htm
 

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there is an excellent Bike article I have at home about every type of engine configuration. I'll try to dig it up tonight and get the specs on it. I remember it talking about firing order and specific crank spacing and the impact it makes at the contact patch.
 

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2OHOH2 said:
1 3 4 2 :idunno:
All l4's have that firing order. In addition, Both inner pistons go up and down at the same time as do the outer pistons. The outer and inner pistons are separated by 180 degrees. Each time one pair of pistons is up, one of them fires (it's completing its compression stroke and starting its power stroke). The other piston is completing its exhaust stroke and begining its intake stroke. Remember that one complete cycle is 720 degrees of rotation.
 

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nedro said:
All l4's have that firing order. In addition, Both inner pistons go up and down at the same time as do the outer pistons. The outer and inner pistons are separated by 180 degrees. Each time one pair of pistons is up, one of them fires (it's completing its compression stroke and starting its power stroke). The other piston is completing its exhaust stroke and begining its intake stroke. Remember that one complete cycle is 720 degrees of rotation.
So in other words, you're confirming what I said :thumb:


Shrub, does that answer your question?
 

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It's not the firing order that makes a Big Bang engine different it's the phasing.....
 

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nedro said:
At what point does the flux capaciter kick in?
Explain phasing if you wouldn't mind please.
Same thing Shrub is talking about...the "pattern" or "phasing" or "crank pin timing".....as opposed to the order.
 

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nedro said:
At what point does the flux capaciter kick in?
Explain phasing if you wouldn't mind please.
:wstupid:

"phasing"? That doesn't have anything to do with Dilithium crystal 5th wave resonance, when combined with Unobtanium, does it? :huh:
 

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Discussion Starter #13 (Edited)
Exactly...if you read the article I linked to above it says that Mick's NSR500 was originally set at 180 degrees so that every 180 degrees a piston would fire. That produced the most horsepower but it also caused the rear wheel to break loose 4 times per revolution rather than just once. They changed the firing pattern to 70 degrees so that all the pistons fire within 70 degrees of rotation causing the rear wheel to have increased stress only once and then for 650 degrees of rotation it would have perfect traction. Make sense? I just wanted to know (now) whether 70 degrees of "phase" is the norm on 4-stroke inline-4's like the 929 or 954 or is it some other degree?

Val Rossi struggled with the same problem. Yammie set his bike up for the most HP and he told them to change the firing pattern so that he had more traction.

-Shrub (aka Kemosabe) :smilebig:
 

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Discussion Starter #15 (Edited)

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Keep in mind when reading that article that they are discussing 2-strokes, so the firing angles are half of what they would be for a 4-stroke....

Edit:
BTW..your bike has a 180° crank...
 

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Discussion Starter #17 (Edited)
Baketech said:
Keep in mind when reading that article that they are discussing 2-strokes, so the firing angles are half of what they would be for a 4-stroke....
The ANGLES are half? So by that logic you are saying the 4-stroke would be 140 degrees? That doesn't seem right. I know that the 2 strokes fire every revolution instead of every other but I didn't that would affect the angle at all?

edit: 180 on the 929? Where did you find that or did you just know it?
 

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WetShrub said:
The ANGLES are half? So by that logic you are saying the 4-stroke would be 140 degrees? That doesn't seem right. I know that the 2 strokes fire every revolution instead of every other but I didn't that would affect the angle at all??
No, it's not the same thing. The Big Bang motors were 2-strokes...so when they mention firing angles you just need to be aware of that.

WetShrub said:
edit: 180 on the 929? Where did you find that or did you just know it
720/4 = 180
Have you ever set the valves on your 929? If so, think about the number of times and degrees of rotation that you spin the crank to get all of the valves in place and it will make sense...
 
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