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Thread: The Sensible Twin

  1. #61
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    Quote Originally Posted by husaberg View Post
    Flat plane Drew, if the crank was 90 degree it would be crossplane.
    http://www.cycleworld.com/2015/08/18...at-plane-crank
    Na. A 4 runs at 90° to be cross plane. But play the percentages, a twin is crossplane at 180°.

  2. #62
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    Quote Originally Posted by Drew View Post
    Na. A 4 runs at 90° to be cross plane. But play the percentages, a twin is crossplane at 180°.
    A 180 crank is a single plane, look down the end of the crankshaft. the crankpins are in a single plane its not rocket surgery.
    Gregs crankshaft is a 180 crank
    https://en.wikipedia.org/wiki/Crossplane
    pay special attention to the last paragraph.
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




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  3. #63
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    Wouldn't it run better if it made some power every time the piston came to the top?
    Don't you look at my accountant.
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  4. #64
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    Quote Originally Posted by F5 Dave View Post
    Wouldn't it run better if it made some power every time the piston came to the top?
    As it hasn't run yet Dave, I'll take that under consideration....Go and have another drink.
    And as it's my thread and I make the rules, the crank is a single plane....

    Why do the awkward buggers live in Wellington ?

  5. #65
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    Quote Originally Posted by Drew View Post
    Na. A 4 runs at 90° to be cross plane. But play the percentages, a twin is crossplane at 180°.
    Yamaha MT07 is a crossplane crank twin @ 270° according to Yamaha. They've been making twins with a 270° crank for a number of years, starting with the TRX 850 from memory. Could be wrong though.
    flashg

  6. #66
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    Quote Originally Posted by flashg View Post
    Yamaha MT07 is a crossplane crank twin @ 270° according to Yamaha. They've been making twins with a 270° crank for a number of years, starting with the TRX 850 from memory. Could be wrong though.
    Also if I remember correctly, The 270° crank was developed as it fires exactly the same as a Ducati L engine, but was more compact being a parallel twin, allowing the engine to be placed more strategically in the chassis to help with handling etc.
    flashg

  7. #67
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    Hmmm. My understanding was skewed it seems. I'd never thought of it past the firing times. But that makes sense to think of it from a mechanical view down the crank.

    So TDM and TRX are cross plane then. Those are quite a nice motor. Wonder why the R1 was so horrid.

  8. #68
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    Quote Originally Posted by Drew View Post
    Hmmm. My understanding was skewed it seems. I'd never thought of it past the firing times. But that makes sense to think of it from a mechanical view down the crank.

    So TDM and TRX are cross plane then. Those are quite a nice motor. Wonder why the R1 was so horrid.
    Possibly because having ensured that they had lower torque losses because of the spacing of power impulses, they decided that they didn't need as much flywheel....It would be interesting to try one with more crank weight.
    Watching one of the few C-P R1's racing at levels last season, it was apparent that there was very little extra throttle needed to go from all the tyre could take to serious wheelspin. A vigorous rider could and did get it sideways and spinning too often for comfort.

  9. #69
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    Quote Originally Posted by Grumph View Post
    Possibly because having ensured that they had lower torque losses because of the spacing of power impulses, they decided that they didn't need as much flywheel....It would be interesting to try one with more crank weight.
    Watching one of the few C-P R1's racing at levels last season, it was apparent that there was very little extra throttle needed to go from all the tyre could take to serious wheelspin. A vigorous rider could and did get it sideways and spinning too often for comfort.
    My initial thought had been that the fly by wire was crap. But that can be tuned and nobody was getting improvement from that. So you're possible right.

  10. #70
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    I rode a mates R1M back roads around wairarapa and it was the easiest thing to ride fast I've ever been on. Way too easy for semblance of safety. Never ridden the newer standard R1 to compare.
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  11. #71
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    Quote Originally Posted by F5 Dave View Post
    I rode a mates R1M back roads around wairarapa and it was the easiest thing to ride fast I've ever been on. Way too easy for semblance of safety. Never ridden the newer standard R1 to compare.
    They must have made them better with the newer ones I can only guess.

  12. #72
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    Quote Originally Posted by Drew View Post
    Hmmm. My understanding was skewed it seems. I'd never thought of it past the firing times. But that makes sense to think of it from a mechanical view down the crank.

    So TDM and TRX are cross plane then. Those are quite a nice motor. Wonder why the R1 was so horrid.
    You're right about firing pattern for the R1, 0°,90°,180°,270°. Followed by the exhaust strokes in the same order. Apparently no inertia, a blip of the throttle is instant. The R1 crank can roll freely on a table. Colin Edward's did this on the promotion of the cross plane crank back in the day. The whole concept was aimed at tyre recovery between pulses as a twin does. The crank is said to be heavier and stronger to handle the extra stresses caused by its design and firing pattern.
    PS I have no idea of the firing order, no reason it couldn't be standard.
    I'd love to know the firing pattern of the current triple if anyone knows. Crossplane maybe ?
    flashg

  13. #73
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    Google helped
    flashg

  14. #74
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    Meh, calling a 120deg triple a crossplane crank is like calling the sky blue. it's the only seriously practical way of balancing a triple.

    And yes, I know all about the 180deg flatplane crank Laverdas. Worked on them, like them, but they're not smooth by comparison to a 120.

  15. #75
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