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XJ variant horsepower

Discussion in 'XJ Technical Chat' started by LarryMc, Mar 26, 2018.

  1. LarryMc

    LarryMc Active Member

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    Im hoping someone can verify the following:

    FZ600=54hp or 56hp/ Bs30 carbs /120 max speed
    YZ600=59hp or 66hp / Bs30 carbs / 125 max speed
    Fj600 =69hp or 72hp / BS32 carbs /130
    Max speed

    Info regarding specs is all over the place. If you have a solid source for the data please include a link
     
    LarryMc, Mar 26, 2018
    #1
  2. LarryMc

    LarryMc Active Member

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    Following up on this, in case your interested, I finally found some reliable data.
    I've changed what is applicable the other stuff is good.

    FZ600 = 68hp
    YX600 = 66hp
    FJ600 = 72hp
     
    LarryMc, Mar 27, 2018
    #2
  3. Kickaha

    Kickaha Active Member Premium Member

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    I would be very surprised if the FJ600 had anything close to 72hp even at the crank
     
    Kickaha, Mar 28, 2018
    #3
  4. bensalf

    bensalf Well-Known Member

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    apparently ,according to my little book , the fj600 is the same engine as my xj600, and indeed is 72hp.
    stu
     

    Attached Files:

    bensalf, Mar 30, 2018
    #4
  5. a100man

    a100man Well-Known Member

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    72 bhp is the widely touted figure, however there appears to be some scepticism (not least from our experienced antipodean member) as to how this 40% uplift (from the 550)was achieved with a 70cc uplift and bigger carbs/valves..
    ..Just sayin'
     
    a100man, Mar 30, 2018
    #5
  6. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Numbers are useless without context.
    What type of dyno was used?
    How many runs, and were the numbers averaged?
    Was the test engine blueprinted (even factories do this)?
    Did the PR department fudge the numbers?
     
    Last edited: Mar 30, 2018
    k-moe, Mar 30, 2018
    #6
  7. XJ550H

    XJ550H Well-Known Member Premium Member

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    i have little widgets that will boost your horsepower by up to 5% so if you add on 20 of them it will boost your horsepower upto 100%:confused:
     
    XJ550H, Mar 30, 2018
    #7
  8. LarryMc

    LarryMc Active Member

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    The numbers are copied from the reviews for each bike from Cycle World. It's Yamahas "claimed" horsepower which I believe is estimated on an average at the crank. So subtract 5% - 15% because of drive mechanism loss and contributing other factors to get a closer value.
    The numbers for these bikes are all over the place.
    If someone has a source for better data. Please share it.
     
    Last edited: Mar 30, 2018
    LarryMc, Mar 30, 2018
    #8
  9. Kickaha

    Kickaha Active Member Premium Member

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    As a comparison a very well put together but fairly stock engined Post classic race bike CBX 550 (which are actually 572cc and 4 valve, 30mm carb) was run on a dynojet dyno here and got 57 rwhp, Honda claimed 65hp @10,000, I'd be surprised if the XJ/FJ had more than that

    If I ever get around to putting the 600 motor in my shed somewhere in my 550 frame I might find out, it'd be nice to find Yamaha were right
     
    Kickaha, Mar 31, 2018
    #9
  10. bensalf

    bensalf Well-Known Member

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    are the widgets for sale.;)
    stu
     
    bensalf, Mar 31, 2018
    #10
  11. LarryMc

    LarryMc Active Member

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    Upon further investigation, I guess the standard drive trane vs crankshaft horsepower loss is 20% on chain driven bikes and 25% on shaft driven bikes.
    15% loss between the crank and rear hub then another 5% loss from the rear tire.
    I got the calculation figure from the Factory Pro website. Evidentally, the 20% loss figure is used as an average industry standard figure.

    XJ550=50hp-20%=40 hp
    YX600 =66hp-20%=52.8 hp
    FZ600 =68hp-20%=54.4 hp
    FJ600 =72hp-20%=57.6 hp
     
    Last edited: Mar 31, 2018
    LarryMc, Mar 31, 2018
    #11

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