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Inline 4 (FZ6) compared to 4 Stroke (FZ6R)

  • Thread starter Thread starter sm00thpapa
  • Start date Start date
04fizzer said:
To be completely honest, almost all ORV's are 4-strokes these days, due to EPA regulations and all. Even the racers have gone 4-stroke. Snowmobiles are also headed in the 4-stroke direction. 2-strokes are all but dead.
Click to expand...
True, there's hardly any 2 strokes out there anymore all you hear is Brrrrap Brrrrap Brrrrap. Hardly ever Ring dingding ding dingding ringdingding. Hahaha!
 
04fizzer said:
To be completely honest, almost all ORV's are 4-strokes these days, due to EPA regulations and all. Even the racers have gone 4-stroke. Snowmobiles are also headed in the 4-stroke direction. 2-strokes are all but dead.
Click to expand...

Well that sux! i haven't paid attention to ORV's lately... here's a :Flip: to EPA and a :cheer: for a 2-stroke comeback! At least until someone find the 8a11s to mount a rotary engine on 2 wheels and make it a production run... I know..

http://thekneeslider.com/images/mazdarotarymotorcycle.jpg

http://www.motorcyclespecs.co.za/Custom Bikes/Rodney Aguiar rotary motorcycle.jpg
 
Most inline 4 stroke 4 cylinder engines have a similar firing order. The fz6(r) engines have a "flat" crankshaft or, each throw is offset 180 degrees from each other. The outer pistons(1 and 4) and inner pistons(2 and 3) move up and down as a set. The firing order is usually 1-3-4-2, each 180 degrees from each other. The New R1 has a cross plane crankshaft, with 270, 180, 90, 180 degree firing interval (not firing order). This puts the each throw 90 degrees from each other, and helps smooth out the power delivery. The firing order is still the same, you just have different amounts of crankshaft rotation between each power stroke.

A standard flat crank inline four also has inherent balance issues. Due to the inline nature and 180 degree offsets, a natural imbalance occurs. It is called a second order imbalance or vibration, since it occurs at a rate of twice the crankshaft speed. This is why on larger engines, a balance shaft (a Mitsubishi invention) is used to cancel those vibrations. The new R1 engines have a first order imbalance, one that occurs at crankshaft speed, so Yamaha uses a primary coupling balancer to quell those vibrations.

V6 engines and bigger (number of cylinders, not displacement) have more leeway in firing order due to more power strokes each crankshaft revolution. The angle of the V also determines the firing order and dictates what type of crankshaft offset is used.
 
You know, I'm really impressed. A guy who'd been flaming away out of his depth a couple of days ago posts a pretty naive question and pretty much gets nothing but straight, well-considered answers.

Y'alls good people. :thumbup:
 
goker said:
Because different people wrote the specs and they both put what they think was important. :)
Click to expand...

Actually because the writer didn't know what the difference was and figured it was 4 of something and wrote it and then the engineer read it and figured it was true and didn't correct it -- 2 different engineering reviewers read the 2 different sheets and didn't compare notes.
:D
Dennis
 
gearheadstu said:
You know, I'm really impressed. A guy who'd been flaming away out of his depth a couple of days ago posts a pretty naive question and pretty much gets nothing but straight, well-considered answers.

Y'alls good people. :thumbup:
Click to expand...

I thought it would be a firestorm also.....that's why I love this place! :thumbup:
 
wolfc70 said:
Most inline 4 stroke 4 cylinder engines have a similar firing order. The fz6(r) engines have a "flat" crankshaft or, each throw is offset 180 degrees from each other. The outer pistons(1 and 4) and inner pistons(2 and 3) move up and down as a set. The firing order is usually 1-3-4-2, each 180 degrees from each other. The New R1 has a cross plane crankshaft, with 270, 180, 90, 180 degree firing interval (not firing order). This puts the each throw 90 degrees from each other, and helps smooth out the power delivery. The firing order is still the same, you just have different amounts of crankshaft rotation between each power stroke.

A standard flat crank inline four also has inherent balance issues. Due to the inline nature and 180 degree offsets, a natural imbalance occurs. It is called a second order imbalance or vibration, since it occurs at a rate of twice the crankshaft speed. This is why on larger engines, a balance shaft (a Mitsubishi invention) is used to cancel those vibrations. The new R1 engines have a first order imbalance, one that occurs at crankshaft speed, so Yamaha uses a primary coupling balancer to quell those vibrations.

V6 engines and bigger (number of cylinders, not displacement) have more leeway in firing order due to more power strokes each crankshaft revolution. The angle of the V also determines the firing order and dictates what type of crankshaft offset is used.
Click to expand...

I was surprised that most inline motorcycle engines use the 180 degree offsets. 90 degree intervals seem more balanced. I guess it's more effort/cost to manage things individually (firing and injection) than for two sets of two.
 
Everyone pretty much covered it, but to the OP, the site that really helped me learn about all this stuff (and much more) is howstuffworks.com

Seriously, I didn't really get 2- and 4-stroke engines before then. Same with understanding gas -vs- diesel engines and why anyone would want a diesel. Extremely helpful site, breaks everything down in easy to swallow chunks with great animated visual aids.

Good luck!
 
gearheadstu said:
You know, I'm really impressed. A guy who'd been flaming away out of his depth a couple of days ago posts a pretty naive question and pretty much gets nothing but straight, well-considered answers.

Y'alls good people. :thumbup:
Click to expand...

I have to say the same. My 'regular' forum is a GTO forum that I moderate. A question like this over there would have resulted in 3 or 4 'good' answers and a bucket full of flames. And we are considered one of the friendlier car forums out there. Kudos to the membership here :)
 
interactive3 said:
I was surprised that most inline motorcycle engines use the 180 degree offsets. 90 degree intervals seem more balanced. I guess it's more effort/cost to manage things individually (firing and injection) than for two sets of two.
Click to expand...

That is exactly the reason. Back in the days of magnetos, you treated in inline four like two pairs of parallel twins. Granted you had a spark for each cylinder during the exhaust stroke (hence the term wasted spark), but it was simple to time and engineer. The "flat" crank was widely used because it a known quantity, and the draw backs were well understood and compensated for (mainly vibration issues, a la GM Quad 4). And a firing interval of 180 degrees made for nice smooth power for street use.

Yamaha changed this in order to help get more traction under race conditions. By spreading out the firing interval, you can get more inconsistent power to the rear wheel, very important when you only have one contact patch(the theory is that the odd firing interval gives the tire more of a chance of holding its grip under power, so you can start applying more throttle earlier as you exit the corner and not break traction). Think of bangs. A normal four cylinder has four big bangs, as each cylinder fires. The "crossplane" Crank turns that in to two big bangs and a long bang. Basically it means two cylinders fire with the normal degree of separation before two cylinders fire one after the other, creating the long bang. It’s this long bang that gives the engine its unique character, sending large pulse of torque to the rear wheel, then giving the tire plenty of time to regain traction before the next one comes around. For automotive use, I would not plan on seeing this form of crank anytime soon. The vibration issues associated with the flat crank is easily dealt with at street RPM levels. And with two or more contact patches supplying power to the pavement (and the prominent use of auto slush boxes:disapprove:) smoothing out the power delivery is a answer to a question no one has asked.

This may help, as it is not the easiest thing to describe in print!
[ame=http://www.youtube.com/watch?v=UvTXMtTTKQw&feature=player_embedded]YouTube - 2009 Yamaha YZF-R1 engine technology explanation[/ame]
 
Not easy to describe is correct. But you sir have done it beautifully!


I must spread rep around before giving it to wolfc again.......:don'tknow:
 
madmanmaigret said:
Not easy to describe is correct. But you sir have done it beautifully!


I must spread rep around before giving it to wolfc again.......:don'tknow:
Click to expand...

Thank you! This is pretty much the extent of my knowledge on engineering of engines. Any more info needed and you are on your own!:D As I have found out over the years, it is much more complicated than even I could dream of. Glad to help out!
 
Ok, so this things been beaten to death. Just thought I'd abbreviate the title and change the title a bit

"Re: Inline 4 (FZ6) compared to Inline 4 (FZ6R)"

Took an FZ6R for a test run about a month back - a really really tame version of the same motor. I know we can talk about throttle bodies, valves, compression, etc. but it felt like i was riding a 500 with no "fun" button above 8k.

(Just in case that is really what the original poster wanted to know).
 
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