Cheddar - no comments about why you find this interesting ?
I would guess that it's got nothing to do with the road bike. Ever since the IL4 1-litre bikes went racing they've forgotten their road manners to some extent. I think many of the changes coming along on these bikes are more suited to racing.
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Sorry, the firing interval of 270-180-90-180 degrees.
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I have to say I much prefer the old carb models over the later injection ones - much smoother pickup. (and I get classic insurance now on my old R1 !).
I thought they were getting a bit silly with them when the first gear top speed went over 100 mph
Edited by martint123 on 09/09/2008 at 15:57
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I agree with the point re carbs though I have ridden a few FI bikes with no problems.
However I am amazed that no one on here finds this interesting, a inline 4 cyl petrol engine though rather than firing at 180deg intervals as they have done so since the dawn of time it fires at 270-180-90-180 degree intervals.
So #1 fires, 270 deg later #3 fires, 180 deg later #4 fires then only 90 deg later #2 fires then 180 deg later #1 fires.
When in cars I wonder.
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Didn't F1 cars play around with this sort of thing many years ago. Honda IIRC in particular.
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Sorry to sound thick; but what is the advantage of this unusual firing order - and what is the usual firing order?
Didn't Lamborghini change their 12 cyl firing order many years ago?
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>>However I am amazed that no one on here finds this interesting<<
I found it interesting enough to post a reply and to look for more details. I'm intrigued as to why Yamaha want to introduce it on a road bike. I hope the local technicians understand it.
My 2002 Yamaha TDM900 also has a 270 degree crank - but in a parallel twin rather than an IL4. Piston arrangements are never going to be as good in a parallel twin as in a boxer or a 90-degree V(/L) twin, but the 270 crank gets round some of the inherent problems.
I look forward to seeing (and hearing) the new R1.
Thanks for posting the data - I wouldn't otherwise have seen it for some time.
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Yep, the TDM fires at 90/270 which actually gives it many of the advantages of a 90deg V twin within a much more compact inline twin.
Yamaha innovation it seems.
I have always quite fancied a TRX850, 850cc 90/270 TDM motor (early TDM 850s were 180 deg) in a sporty trellis chassis.
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Clicked on the Yamaha link hoping to find some performance figures, but if they're there I missed them. Any idea what the 0-60 would be for a one of these? Just curious.
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Honda CB72 250 (10,000 rpm) had an unequal firing interval due to its flat plane crank, back in 1963 or thereabouts. Odd tickover sound but nothing noticeable higher up the rev range unless you had a C15, when you were in unknown territory :)
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Honda CB72 250 (10 000 rpm) had an unequal firing interval due to its flat plane crank back in 1963 or thereabouts. Odd tickover sound >>
Different versions of the CB72 and 77 had either a 360 or 180 deg crank IIRC, i.e. the pistons either moved up and down together (conventional for a twin) or opposite one another, a 4 stroke twin fires once every revolution so I guess the 180 deg crank was timed to fire at 180/720.
This is different to the Yamaha TDM / TRX which has the crank pins at 90/270.
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If the crank pins are at 90/270, then the crank is a 180 degree crank, i.e. flat plane:) Same as the CB 72/77.
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The TDM has one crankpin at 270 degrees relative to the other - so giving the same firing arrangement as a 90-degree V-twin, though not the same balance.
Does the new R1 have balance shafts ?
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That explains it! 90 degrees between the cranks (or 270 looking it at it the other way!)
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If the crank pins are at 90/270 then the crank is a 180 degree crank i.e. flat plane:) Same as the CB 72/77.
The TDM crankpins are 90 degs apart so the piston reach TDC 90 and 270 deg apart, with a 180 deg crank the pistons reach TDC 180 deg apart and with a 360 deg crank they reach TDC together.
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I missed them. Any idea what the 0-60 would be for a one of these? Just curious.
0-60 in about 2.8 - 3.0, only about 0.4 faster than my ZRX1100, sports 600s will also do 60 in the low 3s, the issue with a powerful bike is putting the power down and stopping it wheelying though 0-100 MPH in just over about 5 secs and a quarter mile in around 9.8 at nearly 150mph, i.e. it will do 100 to 150 in under 5 secs.
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0-60 in about 2.8 - 3.0 ...
Wow! Thanks.
F
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It'll all be in the balancing. A straight-4 is the best engine to have as it balances both statically and dynamically. But unfortunately you can't fit a straight-4 into a motorcycle...
Another good example of an unusual firing sequence is the Napier Deltic.
Edited by mfarrow on 10/09/2008 at 22:23
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"you can't fit a straight-4 into a motorcycle"
Straight sixes are a tight fit (CBX, Z1300 and the Benelli Sei 750 are the only ones I know) but straight fours are everywhere! That's what the R1 is - are we talking about the same thing?
Not sure how the asymmetric firing makes it 'smoother than ever', but I expect it sounds nice. 182 horses in a 206kg frame should be quite invigorating, too!
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My Honda RC45 Vee4 has a 360 degree crank, (as opposed to the more the more common 180 degree). This was also the same on the earlier RC30. It makes the firing order uneven (the engine fires in close pairs rather than evenly spaced) and allows the rear tyre to "recover" between firing strokes, thus less likely to spin-up.
Makes for a wonderful "droning" exhaust note, particularly up near the 12,000+ rpm red-line!
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