Wildguzzi.com
General Category => General Discussion => Topic started by: SmithSwede on May 21, 2017, 05:41:02 PM
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One of you engine gurus kindly explain this to me. You often read that a 90 degree V-twin like our Guzzis have a 270/450 firing order. But I don't think this can mean when the pistons fire. So what does "270/450 firing interval" mean? I think I'm missing a conventional meaning or reference point.
Given a common crank pin and 90 degree cylinder angle, when cylinder #1 is at TDC, then necessarily cylinder #2 is at TDC 90 degrees later. Or if you rotate the crank the long way around, then #2 is at TDC 270 degrees later. But a cylinder can only fire when at TDC. Therefore, cylinder #1 must fire, followed by cylinder #2 firing 90 degrees later. The only other possibility is #1 fires, followed by #2 firing 270 degrees later. It's either 90 degrees, or 270 degrees, of separation in the firing points. I'm assuming the latter, which may be what the 270 in 270/450 means.
Question 1-- So which is it? In a Guzzi, does cylinder #1 fire and then 90 degrees later #2 fires? Or is it that #1 fires, then 270 degrees of rotation, then #2 fires?
Question 2--By the above logic, it follows that the cylinders are *not* firing at 270 and 450 degrees, because there is 180 degrees between 270 and 450, not 90, and not 270.
OK,so what does the 270/450 nomenclature mean?
The only thing I can figure is that it means, by convention, that #1 fires at 0 degrees, followed by #2 at 270 degrees later, and that there is then 450 degrees of rotation from the point at which #2 is at TDC for its firing stroke until #1 returns back to TDC for its next firing stroke (i.e. 720-270 = 450).
But that seems odd for at least two reasons. First, this would mean that "270" really does refer to a firing position, but "450" does not. Which is confusing.
And second, why even specify the 450 since it's obvious from the fact that #2 fires at 270 and you have to get back to zero/720 for #1 to be at TDC? Once you state that 270 is the firing point for #2 on a common crank with 90 degree cylinder angle, why specify 450, since it's just obvious arithmetic that (720-270=450)?
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I have a Ducati, it's said the V8 like sound, same as Guzzi, comes from the firing order...V-8's fire every 90 degrees.. But the Guzzi/Ducati firing is said to be 270-405 ...135 degrees????
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Prescott , what is confusing you is the left hand cylinder fires first , not the right hand cylinder .
Dusty
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Prescott , what is confusing you is the left hand cylinder fires first , not the right hand cylinder .
Dusty
So each cylinder fires every 720 degrees with a 90 degree phasing between cylinders?
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I guess 270/450 is referring to the intervals between two bangs in degree.
if you take cylinder #1 as the first bang, the second bang is 270 degree later.
if you take cylinder #2 as the first bang, the second bang is 450 degree later.
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So each cylinder fires every 720 degrees with a 90 degree phasing between cylinders?
Yes.
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Maybe this will explain the differences:
https://en.wikipedia.org/wiki/Big-bang_firing_order
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Kirby--not being argumentative, but the Guzzi simply cannot have 180 degree between TDC firing events. The cylinders are 90 degrees apart. Therefore, since firing must occcur at TDC, firing must be separated by 90 degrees (going around the short way) or 270 degrees (going around the other, longer way).
That's what bugs me!
But you are totally right--the engine is magical, and it doesn't matter if you understand the geek stuff to appreciate the magic.
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The crank rotates clockwise when viewed from the front.
Left hand pot can be #1 so it fires, at that point the RH cylinder, #2 is on its induction stroke but the crank rotates through 270 degrees to bring #2 up to TDC compression.
#2 then fires and at that point #1 is on the of exhaust stroke but has the entire induction and compression cycle to go, plus the end of the exhaust stroke. So another 450 degrees before #1 fires again.
Each cylinder has a 720 degree cycle. I don't see what's so hard to understand???
Pete
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Maybe this will help?
https://www.youtube.com/watch?v=v70MXzekosw
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Smithswede, your original question is not a stupid one and your confusion is very understandable.
Firing order for any engine depends on its cylinder layout and crank pin configuration. The degrees between the cylinders, the number of crank pins on the crankshaft and the angles between them all determine the firing order.
The Guzzi is a V-twin with 90 degrees between the cylinders and both pistons connected to a single crank pin on the crank shaft. One cylinder fires 270 degrees after the preceding one whose next firing is then 450 degrees later.
https://www.youtube.com/watch?v=ZQuqkh3ZEo4
These motors could have valve timing set so that the cylinders fired in quick succession, 90 degrees apart, with a long spin in between but they are not.
By juggling crank pins stagger, manufacturers can produce engines of many different cylinder configurations to have virtually any firing order they desire.
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The Gizzi has a 180 deg separation between firing. In other words the cylinders fire 180 deg apart.
Ummmm Does that need a re think ??? Just for the sheer fun of it, grab a 2 metre tape measure and lie it on a piece of paper. Zero is your start point. Make a dot at 90 mm (that's a representation of 90 degrees) and another one every 720 mm from that point on for a couple of metres, they can be the ignition points for cylinder #1. Now go back to the zero and count forward 360 mm (one crank rotation)and make a dot 180 deg after that ( 360+180=540) now you have a dot where number two fires so measure forward 720 mm from there and do that for a couple of times. What you will now see is a linear representation in mm of the circular rotation of the crank in degrees. You will notice the "loping" interval so obvious to the ear. There's nothing wrong with trying to understand more about your bike, and the suggestion to "just ride it" is a decision for you to make for yourself. If you want to do what I suggest and follow the plan, you'll see what I mean. Remember that each cylinder fires 720 deg after it's previous ignition. If people "just rode" their bikes, there'd be no upgraded maps, or plates in the sump, or good advice on rollerising 8V motors. I'm being careful not to " shit anyone to tears" , or paint them as oracles, but lucky for us that there are people with enquiring minds. We are better for it..
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Nobody is suggesting the question is stupid, it's just it is really quite simple when you sit down and think about it. Probably drawing a diagram for yourself with a protractor might make it easier.
Pete
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?Have you never adjusted the valves on your Guzzi?
:-)
Does that actually mean anything ? That's un related and immaterial. Was there a point somewhere in there?
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OK,- my version
When you describe the firing order, you have to start somewhere. Not starting with the crank position of one cylinder firing would be confusing.
As Dusty points out, the LH cylinder is the #1 cylinder. And with LH cylinder just firing, that is point 0 - zero degrees, the starting point.
And then,- after 270 degrees of crank travel, the RH cylinder fires.
And then,- after 450 degrees of crank travel, the LH cylinder fires.
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Yes you are correct, I ment to start the crank rotation from 45 degrees from the top! I will correct.
Thanx
I have removed my reply with quote of your earlier reply, so that it won't further confuse those who are confused :thumb:
I never take the guzzi engine timing seriously until the timing chains of my mate's Stelvio dropped during the rollerisation.
A sketch on greasy paper during coffee break helped me understand the firing order and timing of the 8V engine.
Hardest part was convincing my mate to have faith in me before we thumbed the started button.
(http://i67.tinypic.com/10gz4ap.jpg)
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OK,- my version
When you describe the firing order, you have to start somewhere. Not starting with the crank position of one cylinder firing would be confusing.
As Dusty points out, the LH cylinder is the #1 cylinder. And with LH cylinder just firing, that is point 0 - zero degrees, the starting point.
And then,- after 270 degrees of crank travel, the RH cylinder fires.
And then,- after 450 degrees of crank travel, the LH cylinder fires.
Yeah , kinda thought that explained it , guess not LOL
Dusty
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Well, here's where I have arrrived.
Let zero degrees be the reference point, with #1 left cylinder at TDC and beginning its power stroke.
#1 fires and the crank then rotates the "long way around" for 270 degrees until cylinder #2 is at TDC and ready for its firing stroke.
The crank then rotates ALL THE WAY back to the starting point, i.e. back to zero, or what you might call 720 degrees. Only then is #1 cylinder again back at TDC and ready to begin its power stroke.
Here's the source of the confusion. If zero is the reference point, with #1 at TDC for its firing stroke, then "270" really is the number of degrees (from reference point zero) at which #2 is at TDC and ready to do its firing stroke.
But it is false to say that #1 fires again at 450 degrees (meaning 450 degrees from the zero reference point). In fact, nothing can fire at 450 degrees because #2 is at BTDC and #1 is halfway between TDC and BTDC.
It is also false to say that #1 and #2 ever fire 180 degrees apart. No, they fire 270 degrees apart, and then 450 degrees apart (360 for 1 full revolution + another 90 degrees to account for the 90 degree cylinder bank angle). They can't fire 180 degrees apart, since that's geometrically impossible.
To my way of thinking, it would be less confusing to say that the firing order is 0-270-720.
But Phang is absolutely correct---"270/450" makes sense if you read that as the "intervals in degrees between bangs." But it is just false to read "270/450" as "when the cylinders fire in relation to a zero reference mark."
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I like bacon...
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I like bacon...
Wrap some cheese and little smokey stuffed jalapenos with it and smoke it for two hours.. :thumb:
:smiley:
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will do... :boozing:
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I think everybody's saying the same thing in different ways. :smiley: Except for the bacon..
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If that jet plane were on a giant treadmill, would it be able to take off? :evil:
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Wrap some cheese and little smokey stuffed jalapenos with it and smoke it for two hours.. :thumb:
:smiley:
ABTs + Chuck's Chicken Wings :food: made a great Sunday night with my two sons. :thumb:
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Ok, this is my last shot 'cause I'm leaving on a jet plane!
Every 720 degrees of rotation of the crank the cylinders fire one time..at position 270 degrees and 450 degrees. I think that that is 180 degrees apart.
Done.
:-)
sorry the difference from #1 & #2 isn't 180, it's 450. Then another 270 back to #1.
I think folks have confused subtraction with addition.
Imagine that your engine is a clock, start at 12 0'clock and go to 9 o'clock (#1 fires), then back around to 12 O'clock the SECOND time (#2 fires) and start all over again.
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sorry the difference from #1 & #2 isn't 180, it's 450. Then another 270 back to #1.
How very right you are !
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How very right you are !
unfortunately, I'm the guy here with no mechanical aptitude. :undecided:
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unfortunately, I'm the guy here with no mechanical aptitude. :undecided:
Mechanically you may be shithouse, but you've got basic mathematics sorted :bow:
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Did someone say bacon? :food:
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Did someone say bacon? :food:
And hushpuppies :laugh:
Dusty
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If that jet plane were on a giant treadmill, would it be able to take off? :evil:
Yup.
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I've wondered why the cylinders were numbered right to left ( from the seat) rather than the standard left to right. The answer is simple and it dawned on my thick head as I was looking at an engine on the bench: front to back, another standard.
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OK,
For you engineering students.
: May 23, 2017 6:43 AM
Left cylinder fires, engine turns to the 270 degree position and #2 fires then engine turns to the 450 degree position and # 1 exhausts and starts intake, engine turns to the 270 degree position # 2 exhaust and starts intake, engine turns to 450 position on compression and fires then engine turns to the 270 degree position and fires.
These two firings are 180 degrees apart,(measured in the direction of rotation), position wise.
In engineering parlance this is what is called a 180 degree firing order.
First semester 101.
No Kirby, the firings are 270 and 450 degrees apart.
Look at your clock, start at midnight, #1 fires at 9am (270 degrees), the clock goes past noon and back around again to midnight (450 degrees) and #2 fires. start again.
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Mmmmm hushpuppies. I've gotta say that the Cedar Vale specials were the best I've ever had.
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next you'll be telling me that you fry hushpuppies at 180 degrees.
I'd recommend 270, better yet 450 degrees. :food:
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325 degrees , just to be a contrarian :evil:
Dusty
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yep Dusty............45 0 is wayyyy toooo hot.
But we gotta ask Chuck. I use his recipes for Buffalo Wings and ABTs.
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325 degrees , just to be a contrarian :evil:
Dusty
Nobody's got their undies in a bunch (yet), but someone is RIGHT and someone is WRONG... I can understand the desire to get some water on this before it catches fire, but there are couple of luminaries here who don't have things the correct way around and on Wild Guzzi that's just not a good thing. And while we're all being schooled, can we delineate between "firing interval" and " firing order". One is a representation in degrees between successive ignition points and the other is information regarding the numerical order in which each cylinder fires, distributed around two revolutions. For example, on a standard V8 you could mess around enough with the camshaft, ignition and alter the firing 'order" but the firing "interval" will always be 90 degrees if you leave the crankshaft alone. But (as usual) I digress, back to the Guzzi. We must start at the top of the "clock" at zero degrees and only measure degrees of rotation from that fixed reference, not degrees from the last firing. Mixing the two will end in tears. Saying that #1 fires at the top of the clock at zero degrees will give a different answer to saying it fires at 3 o'clock ( or 90 degrees), this I think is where the schools of thought are diverging. BTW, the word is " you're" not "your" and where is Kev m when you need him ? :popcorn:
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Peter , what are you talking about :huh:
Dusty
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Did someone say bacon? :food:
Do I detect a trace of thread drift here?????
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Definitely this thread has the potential to be Thread of the Month - perhaps a new category we can develop for the Winning Controversial thread. Have managed to get a couple of good chuckles seeing the back and forth here...
Prescott...I just have to say you picked a nice prickly topic to divide the pilots on the board...looking forward to the ongoing debates here on Firing intervals, orders and degrees of separation on when ignition takes place!
Carry on gents!!
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Peter , what are you talking about :huh:
Dusty
PM'd
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Definitely this thread has the potential to be Thread of the Month - perhaps a new category we can develop for the Winning Controversial thread. Have managed to get a couple of good chuckles seeing the back and forth here...
Prescott...I just have to say you picked a nice prickly topic to divide the pilots on the board...looking forward to the ongoing debates here on Firing intervals, orders and degrees of separation on when ignition takes place!
Carry on gents!!
It's the one about taking off on a treadmill that nearly got me ! I get sucked in every time... :embarrassed:
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:laugh: :laugh: :laugh:
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And yes.... Great thread SS
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If that jet plane were on a giant treadmill, would it be able to take off? :evil:
Yes. The speed of rotation of the wheels is not relevant to airspeed. Planes are not wheel driven.
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The treadmill conundrum came from another motorcycle forum. It was mostly tongue-in-cheek, but it went on for months.
Sort of like the Durrani wheel thread, which went on for years, with dozens of thread-jacks.
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(http://images.gizmag.com/inline/honda-vultus-nm4-53.jpg)
this makes me wonder if they've ever done a "tw-ingle" 90/630?
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(http://images.gizmag.com/inline/honda-vultus-nm4-53.jpg)
this makes me wonder if they've ever done a "tw-ingle" 90/630?
That's a good graphic
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That's a good graphic
I like it too, means V twin Guzzis have a 360 crank, dunnit ?
Just the barrels are on funny
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I like it too, means V twin Guzzis have a 360 crank, dunnit ?
Just the barrels are on funny
Unlike V style engines, parallel inline engines can have individual pistons firing independently from all the others. (Although GM brought out a like of 90 degree V6 engines with an off set crank that made them fire like a smooth 60 degree engine.)
I don't understand how a 90 degree V twin can have a 360 crank since there is always a 90 separation from the two cylinders...... I can only figure 270/450 or 90/630
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http://www.cycleworld.com/2016/02/01/motorcycle-v-twin-and-parallel-twin-and-flat-twin-engine-tech-sound-insights
Let's go crazy: Kevin Cameron knows it all. And to complete the circle for Kirby:
Another way to build V-twins is with Honda’s “offset dual-pin crankshaft.” Normally, the only way to balance a single crankpin V-twin is by giving it a 90-degree V-angle, as described above. But Honda found that by using two crankpins instead of one, and by offsetting them by the correct angle, a self-balancing V-twin could be built with any cylinder V-angle–without need of any balance shaft. To get this effect in a given engine, we subtract twice the V-angle from 180-degrees to find the correct crankpin offset angle. Thus, in a 90-degree V-twin (Ducati, Guzzi) this is 180 – (2 X 90) = 0 (no crankpin offset, which is what Ducatis and Guzzis have). If we want to balance a 45-deg V-twin, the numbers become 180 – (2 X 45) = 90-degree crankpin offset.
Carrying this out requires a rather wide crankcase, as there has to be some way of connecting two crankpins spaced 90 degrees apart at its center. This takes the form of a 3rd flywheel disc.
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So...I just have one question for Prescott now. Is this as clear as mud or does it make sense to you now, or would a long ride from Dallas to Datil be necessary in order to work out the firing order while on the road! One thing we haven't injected here into the discussion is how do spark plugs feel when you are not sparking...do they feel left out or jealous while the other plug is getting its chance at being sparkly?
:)
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One thing we haven't injected here into the discussion is how do spark plugs feel when you are not sparking...do they feel left out or jealous while the other plug is getting its chance at being sparkly?
:)
ahh... now I know why the spark plugs of the BMW boxer look happier, they get fired equally amount of time by the waste spark ignition system...
also, should we factor in the timing advance when we discuss the firing angles? I don't think guzzi engine will run with usable power if the spark plug really fire exactly at 270/450 :afro:
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Phang, yes, I know for certain that a BMW airhead has a wasted spark system.
And Paul, I now understand this to my satisfaction, but I was apparently correct that this is quite confusing.
And you are correct---when the spark plugs on my small block are not firing at all, that would be a "0/0" firing order.
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Now I'm really curious about the concept of a 90/630 V twin.
As I understand a "twingle," that's a two cylinder engine set up so that both cylinders are firing at the same time. So it's just like a single cylinder thumper, except that there are two cylinders firing, not just one.
But a Guzzi 90/630 V twin would not really be a "twingle," since the firing strokes would be 90 degrees off, not simultaneous.
Maybe we should call the 90/630 a Guzzi Quasi-Twingle.
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You never want to ride a twingled Brit Vert twin , like Kirby said "ugly vibration" . Yes it was done specifically for traction on dirt tracks . I actually owned a 500 CC BSA framer way back when , shook worse than a Victor :shocked: Damn , my hands just started hurting from the memory :rolleyes:
Dusty
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Mmmmm hushpuppies. I've gotta say that the Cedar Vale specials were the best I've ever had.
And I can say with equal conviction that the cedar vale hushpuppies were the FIRST ones I ever had.
but this thread is about BACON! :drool:
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I don't think guzzi engine will run with usable power if the spark plug really fire exactly at 270/450 :afro:
You don`t ?
Even if the firing point of #1 cylinder has been point zero, throughout this thread ?
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You don`t ?
Even if the firing point of #1 cylinder has been point zero, throughout this thread ?
Ben , I think Phang is referencing ignition lead .
Dusty
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Oh well then-.
BTW - has anybody checked the treadmill recently, to see if the bearings are properly greased ? :cheesy:
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Oh well then-.
BTW - has anybody checked the treadmill recently, to see if the bearings are properly greased ? :cheesy:
Is it a Guzzi treadmill ? :laugh:
Dusty
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Is it a Guzzi treadmill ? :laugh:
Dusty
No, it is not. Guzzi has only built motorised devices AFAIK.
(http://thumb.ibb.co/c5tzLv/Picture_511.png) (http://ibb.co/c5tzLv)
image hosting (http://da.imgbb.com/)
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I must admit that my Breva 750 does not have those problems with fixed firing points. I have come up with an ingenious system where the crank pin is actually supported in roller bearings at each end, and these run in eccentric tracks machined in to the flywheel.
Stick with me here. You can probably begin to see that the firing order will not be in the same position each time. To enable this to work I have devised two cunning systems, the Performance Induction Sensor System, or P.I.S.S. to feed the motor at the correct time, and the Continuous Rotating Analogue Potentiometer system to fire it, known as C.R.A.P. You might think that this was a lot of work to find a solution to a non-existant problem, but I can assure you that when P.I.S.S. and C.R.A.P. are tied in with my cunning flywheel arrangement things really hum! :thumb:
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A 360 degree crank just means a single (common to both rods) crank pin.
So is that the case with a 650 Yamaha twin for example ?
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So is that the case with a 650 Yamaha twin for example ?
Yes , as well as the 500 CC Hosk from which the Yamaha was developed . The Vert twins from Jolly Olde were 360% also . Technically they don't have to share a crank pin , the two pins simply have to be in alignment .
Dusty
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Yes , as well as the 500 CC Hosk from which the Yamaha was developed . The Vert twins from Jolly Olde were 360% also . Technically they don't have to share a crank pin , the two pins simply have to be in alignment .
Dusty
Yep thanks Dusty.
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Jeepers SS, you really know how to get a conversation started. :popcorn:
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OK,
For you engineering students.
: May 23, 2017 6:43 AM
Left cylinder fires, engine turns to the 270 degree position and #2 fires then engine turns to the 450 degree position and # 1 exhausts and starts intake, engine turns to the 270 degree position # 2 exhaust and starts intake, engine turns to 450 position on compression and fires then engine turns to the 270 degree position and fires.
These two firings are 180 degrees apart,(measured in the direction of rotation), position wise.
In engineering parlance this is what is called a 180 degree firing order.
First semester 101.
Boy, I don't look at this thread for two days and it goes ballistic.
Kirby, your explanation quoted above is not correct. To re-state it:
The left cylinder fires, the crank rotates 270 degrees and the right cylinder fires. The crank rotates an additional 450 degrees and the left cylinder fires and the cycle continues.
(Note: there are 360 degrees in one revolution. Because this is a four stroke engine it takes two revolutions to complete a cycle. 270 + 450 = 720 = 2 revolutions.)
Because the cylinders are 270 degrees apart (measured in the direction of rotation) this is the same as a 270 crank in a parallel twin. The chart of the 270 crank shows the firing sequence of the Moto Guzzi engine.
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George Bernard Shaw said something like "The single greatest problem with communication is the illusion it has taken place". Rodekyll (really enjoyed getting to meet you at CV) wrote something to the effect he got on the interstate at night because "trucks squash the deer into more manageable chunks". I think this thread has squashed this dead horse into bite sized pieces. :evil:
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Kirby, you're subtracting the difference, incorrect. You should be adding them to 720.
The firing is NOT 180 between the two fires, it's 270 and then 450. It's 270 degrees after #2 fires and 450 degree after #1 fires.
Look at your clock, start at midnite and #1 fires at 9 am (270 degrees later), go around the clock pass noon and go to midnite and #2 fires (450 degrees later). start again
Also, with straight crank pins there is no way a 90 degree V twin can have a 180 degree firing interval. Geometry.
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Keep in mind that we are not talking about ACTUAL firing degrees but the 270/450 nomenclature refers to engineering architecture only, for classification purposes.
Yeah , with all due respect to the other participants on this thread , how many of you guys are engineers ? Well , besides Kirby .
Dusty
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Yeah , with all due respect to the other participants on this thread , how many of you guys are engineers ? Well , besides Kirby .
Dusty
Me, I love mechanical engineering so much till I decided not to make it a career. I chose electrical & electronics engineering in university (college) instead. :grin:
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Me, I love mechanical engineering so much till I decided not to make it a career. I chose electrical & electronics engineering in university (college) instead. :grin:
So THAT'S why you keep bringing up sparking plugs , it all makes sense now :grin:
Dusty
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Yeah , with all due respect to the other participants on this thread , how many of you guys are engineers ? Well , besides Kirby .
Dusty
well then, perhaps you can explain the 180 degree firing that many of us here don't understand. Obviously either someone is wrong, or we have a communication gap.
I am open to be educated here but haven't a clue what the 180 actually means. I know it's not the firing interval (9 AM and Midnight) , so what is it? (Unless it's Kevin Cameron's explanation of making an offset crank)
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Kevin Cameron is my go to guy , but Guzzi crankshafts aren't offset . That example doesn't apply in this conversation .
Dusty
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Kevin Cameron is my go to guy , but Guzzi crankshafts aren't offset . That example doesn't apply in this conversation .
Dusty
my point exactly.
So what is the 180? :smiley:
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Anyone been fishing lately , heard the crappie are biting .
Dusty
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Kevin Cameron is my go to guy , but Guzzi crankshafts aren't offset . That example doesn't apply in this conversation .
Dusty
I like to read his articles too, I keep his book next to my bed :thumb:
(http://i68.tinypic.com/w2ehag.jpg)
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Hey those are familiar!
Used to love to stay at the Raffles! Done all the tourist stuff and just relax.(and food!!!) Being so close to the equator no typhoons?
What's the life expectancy of a new auto these days?
Cheers.
:-)
It's warm , humid and torrential rains, no typhoon :grin:
It's still 10 years, same for the motorcycle too. My Griso is 7 years old now, it will expire in another 3 years. I have to pay a substantial amount of money if I want to carry on to ride it for another 10 years :violent1:
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Unaware that it included motos!
Cheaper to get a new one? (is there a cc point for the 10 yr rule?
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Unaware that it included motos!
Cheaper to get a new one? (is there a cc point for the 10 yr rule?
A new one has to pay the same 10 years tax too. It is across the board regardless of the engine capacity.
I would like to tell you more but let's just stay on the topic.
I'll start a new topic about the costs of motorcycle ownership in Singapore :azn:
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A new one has to pay the same 10 years tax too. It is across the board regardless of the engine capacity.
I would like to tell you more but let's just stay on the topic.
I'll start a new topic about the costs of motorcycle ownership in Singapore :azn:
Weren't we discussing fishing ?
Dusty
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Thank you for the explanation of the 4 stroke cycle but..
Read it again I was talking about the firing positions of 270/450 which are 180 degrees apart hence the engine is considered to have a 180 degree firing cycle. (response to original question from op)
The 2 positions in degrees that the engine fires in a 720 cycle.
Keep in mind that we are not talking about ACTUAL firing degrees but the 270/450 nomenclature refers to engineering architecture only, for classification purposes.
OK, I went back and read the original post. The question asked was why is the 270/450 nomenclature used instead of firing position values.
Answer. Because using the degrees between firings the sum adds up to 720. 270 + 450 = 720. This is always true regardless of configuration. Using this method provides a check sum.
If you use the firing position values they may or may not add up to 720. For the Moto Guzzi 90 degree twin the firing positions (relative to zero) are 270 and 720. 270 + 720 = 990. (Or 0 and 270)
PS: I am a Mechanical Engineer, BSME and Registered Professional Engineer
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WOW! Sure wouldn't want to see the thread if we were discussing something with a more complicated firing order, like a flat-plane 60 degree V-8. Or, an 18 cylinder radial. Or, a 9 cylinder rotary.....
Anyways, I'll take an AR10 over an M14 ANY day!
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OK, I went back and read the original post. The question asked was why is the 270/450 nomenclature used instead of firing position values.
Answer. Because using the degrees between firings the sum adds up to 720. 270 + 450 = 720. This is always true regardless of configuration. Using this method provides a check sum.
If you use the firing position values they may or may not add up to 720. For the Moto Guzzi 90 degree twin the firing positions (relative to zero) are 270 and 720. 270 + 720 = 990. (Or 0 and 270)
PS: I am a Mechanical Engineer, BSME and Registered Professional Engineer
you're kidding, I take it.
And I am still clueless about the 180 degree interval.
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WOW! Sure wouldn't want to see the thread if we were discussing something with a more complicated firing order, like a flat-plane 60 degree V-8. Or, an 18 cylinder radial. Or, a 9 cylinder rotary.....
Anyways, I'll take an AR10 over an M14 ANY day!
This firing order stuff is more or less an abstract problem...I have a hard time with abstract but not looking at real life stuff...Visualizati on of a P&W R2800 is no problem because I have seen the parts in person...
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(http://thumb.ibb.co/kSmHQv/thread_that_wouldnt_die.jpg) (http://ibb.co/kSmHQv)
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This firing order stuff is more or less an abstract problem...I have a hard time with abstract but not looking at real life stuff...Visualizati on of a P&W R2800 is no problem because I have seen the parts in person...
How's the fishing in rural N.Y. Tony ? :rolleyes:
Dusty
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How's the fishing in rural N.Y. Tony ? :rolleyes:
Dusty
Well, I live three miles from Lake Ontario...About 40 miles north the Finger lakes, we have a half acre pond on our property with small mouth bass and blue gills, several streams nearby with trout...I have no interest in fishing... :laugh:
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I tell you Dusty, the answer is ALWAYS bacon. Accept that. Embrace it. Then all mysteries of life willl be revealed.
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I tell you Dusty, the answer is ALWAYS bacon. Accept that. Embrace it. Then all mysteries of life willl be revealed.
Yeah , except I really don't like bacon , so what then ? :laugh:
Dusty
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Well, for those with religious, personal taste, or too many reads of "Charlotte"s Web" that make bacon eating distasteful, there is an alternative fact available. That answer is "C". :azn:
But you knew that, or you wouldn't have made it this far.
I think I may have read somewhere once* that the bacon gene is either cultured or dies in the early years, like the yearning to push buttons, or disassembling stuff. Some kids get it, some don't. Like the natural attraction to the edge of high places and cat boxes, all babies are born with the natural expectation to like bacon, but for some sad souls, like the little boy surrounded by wonderful machines who grows up and goes liberal arts instead of vocational science, the gene does not exist. For them, more the pity. For me, more BACON!!
* no, I didn't.
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:laugh: :shocked: :laugh: :shocked: :laugh: :shocked:
Dusty
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so what do you cook at 9 am? what about midnite?
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you're kidding, I take it.
And I am still clueless about the 180 degree interval.
Kidding about what?
What 180 degree interval? There is none on the Moto Guzzi twin. Are you referring to 450 - 270 = 180 ? That is not a valid equation because the 450 degrees is not from the initial starting point. It is from the 270 degree point. The proper equation is 450 + 270 = 720 (2 revolutions of the crank).
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Kidding about what?
What 180 degree interval? There is none on the Moto Guzzi twin. Are you referring to 450 - 270 = 180 ? That is not a valid equation because the 450 degrees is not from the initial starting point. It is from the 270 degree point. The proper equation is 450 + 270 = 720 (2 revolutions of the crank).
We are in total agreement. I posted the same thing several times earlier in this thread...... or you could say the firing interval is 9AM and Midnight. :wink:
the 180 business was posted by someone else and never clarified..... it's not possible with the geometry of a 90 degree V twin
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Yeah , with all due respect to the other participants on this thread , how many of you guys are engineers ? Well , besides Kirby .
Dusty
Could be any one of us Dusty..
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Could be any one of us Dusty..
That explains alot , a carpenter would just set the valves and the TPS , check the tires , and ride the dang thing :shocked:
Dusty
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I've wondered why the cylinders were numbered right to left ( from the seat) rather than the standard left to right. The answer is simple and it dawned on my thick head as I was looking at an engine on the bench: front to back, another standard.
From the seating position, they ARE numbered left to right.
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That explains alot , a carpenter would just set the valves and the TPS , check the tires , and ride the dang thing :shocked:
Dusty
can you do dovetail joint? I always find it fascinating
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can you do dovetail joint? I always find it fascinating
Sure , not much call for that now though .
Dusty
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WOW! Sure wouldn't want to see the thread if we were discussing something with a more complicated firing order, like a flat-plane 60 degree V-8. Or, an 18 cylinder radial. Or, a 9 cylinder rotary.....
Anyways, I'll take an AR10 over an M14 ANY day!
M14 anytime! (the Vedeneyev M14P 9 cyl radial...)
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M14 anytime! (the Vedeneyev M14P 9 cyl radial...)
M14 because you like things that don't work when dirty!? When in the Corps we mud tested AKMs, M14s, M16s (same architecture as AR10/AR15), M1 Garands, FNALs and a few others. Bet you can't guess which type worked EVERY time and all the rest failed a lot?
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The AK.
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The AK.
Uh... No. It's bolt is just as open to the elements as an M1 Garand or an M14 or an FN.
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Uh... No. It's bolt is just as open to the elements as an M1 Garand or an M14 or an FN.
Well, almost as open. The AR15/M16 worked every time. The AKM and FN FAL were second and the M14/M1 Garands NEVER worked in the mud test.