5th Gen Dyno Reading 72hp? WTF?

Discussion in 'Mechanics Garage' started by adeyren, Dec 4, 2014.

  1. adeyren

    adeyren New Member

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    Just had my bike fitted with Power Commander V today at an authorised Dyno dealer today here in the UK.As the pic below shows its only giving me 72 hp before and 77hp after!
    Guy reckons when he first tested it she was running really lean and even after only a 5hp increase. Could be caused by a blocked injector or faulty fuel pressure.
    The bikes fitted with a Delkovic exhaust and K and N filter. Now i wasnt expecting a big increase in power but to have such a low reading beforehand somethings wrong. To get the injectors cleaned properly is about $250! Am a bit loath to spend that until maybe you guys can throw some insight into maybe why. Mileage is 26000 miles on a 2001 plate.
    I thought standard bhp was approx 90 - 95hp and torque approx 55ft lb? I know theres a difference between hp and bhp but nearly 25%??
    Bike goes well enough but not enough as i supposed. It does now give an occasional stutter at low revs and seems to exhaust pop more now on the over run.
    Any thoughts ideas i would be most grateful. To say i am a bit p...d off is an understatement especially after spending $650 supplied and fitted!!
    Dyno Reading_0001.jpg
     
  2. TNRabbit

    TNRabbit New Member

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    I personally don't think the PC juice is worth the squeeze.

    i had my bike checked (all stock 5th gen) on a dyno this past May & it was 106 hp at the wheel. Something definitely isnt' right with your bike! Have you checked for stored FI codes?
     
  3. NormK

    NormK New Member

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    I know your bike is only 13 years old but a couple of weeks ago I did the relay mod to the coils on my 82 CB750F it had a misfire around the 100kph and popping in the exhaust when backing off. Relay to feed 12 volts straight into the coils got rid of these problems and made starting so much easier, hit the button and it fires. Removes the problem of dragging the power to the coils through several connectors, ignition switch,kill switch each of these all cause a drop in power. May not be the cause but you never know
     
  4. V4toTour

    V4toTour New Member

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    pull your spark plugs and check coloring.
     
  5. adeyren

    adeyren New Member

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    Gonna check the plugs and coils this weekend. Another thing is the bike now ticks over at 1300rpm after the dyno run, previously was 750 ish.
     
  6. Gweglez

    Gweglez New Member

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    1300 sounds more like it tbh but that's judging from the perspective of my vtec
     
  7. CandyRedRC46

    CandyRedRC46 Member

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    wow thats a high reading dyno lol
     
  8. OCLandspeeder

    OCLandspeeder New Member

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    Magazine tests of the time consistently gave at least 100 rwhp for the 5th generation VFR's with stock map and pipe.
     
  9. CandyRedRC46

    CandyRedRC46 Member

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    Right but the vfr800 is rated at 106 at the crank... Lol

    TNT Rabbit must have one of those magic frictionless gearboxes ;)
     
  10. NorcalBoy

    NorcalBoy Member

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    Anytime people start talking dynos things go pretty sideways in a hurry, after all, what's 10-20hp over or understated amongst friends? 106 hp at the crank on a 6g....... I'll take "What junkies shoot in their arms for a thousand, Alex".
     
  11. TNRabbit

    TNRabbit New Member

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    I fibbed; that reading was with a D&D slip-on pipe.


    [​IMG]

    [​IMG]
     
  12. Y2Kviffer

    Y2Kviffer Insider

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    TNRrabbit ... that dyno appears to be generous, not uncommon to see them run on the high side. Mine dyno pull was 96.3 hp with pipe and K&N....which is inline with what I've read.

    adeyren ... that 1300 rpm idle would be normal, not the 750rpm. When were the plugs last changed? 5th gens are recommended at 8,000 miles. You may also want to run some seafoam in your next tank of gas.
     
  13. NorcalBoy

    NorcalBoy Member

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    Calling it generous is being generous.....
     
  14. adeyren

    adeyren New Member

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    I haven't changed the plugs since i bought her 6000 miles ago. The dealer should have changed them or so he says. A plug change was amongst my winter project list to do anyway. Got the bike booked in at another dealer next week. I haven't touched the bike since the last run so i can get a good comparison of two dynos. I don't think the guy pinched off the pair valves last time either. The bike always ran at 750 rpm at idle before no problem so perhaps that figure was wrong. Just checked my manual says idle speed 1200rpm so mine was low. Will keep you posted when i get the next run results and hopefully with air/fuel ratios.
     
  15. CandyRedRC46

    CandyRedRC46 Member

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    Its hard to believe that the bike could idle that low with out stalling. A lot of numbers on this thread are very questionable.
     
  16. GreyVF750F

    GreyVF750F Member

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    TNRabbit what type of dyno was this on? I've always seen tq and hp cross at 5250rpms on every engine/chassis dyno. Yours look to cross around 9800rpms.? That's strange because the equation for hp is: HP = (TQ*RPM)/5250

    So if you take your max tq of 55.8831 x 8522rpms/5250 = 90.71hp. of run 048 and the other run 049 @ tq 56.245 x 9069rpms/5250 = 97.159hp. Though your dyno says 105.3571 and 106.2234 at the top. Somethings bogus here. JMO

    Granted horsepower is just a calculated number and not something that can be measured alone like torque.
     
  17. CandyRedRC46

    CandyRedRC46 Member

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    Because they are on different scales ;)
     
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