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Info Is Kawasaki bringing back the ZXR250 (ZX25R RUMOUR MILL) ?

Discussion in 'Kawasaki 250cc In-line 4's' started by kiffsta, Jun 25, 2014.

  1. DannoXYZ

    DannoXYZ Active Member

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    There's lots that can be done over factory 250s from '90s. Those 250 4-cylinders with 45bhp were actually restricted to comply with gentlemen's agreement between manufacturers. All had ways to remove this limit and get more power (Honda's smart-card may be most difficult to hack). Dave Moss's '93 CBR250RR gets 58bhp. Many, many people suspected he had 55-60bhp due to his laptimes before he posted his dyno-charts, which confirmed 58bhp.

    - With modern fuels, you can run 12.5-13.0:1 compression easily. Many factory bikes are running +13.0:1 with bigger bores than 250s

    - retard intake-cam timing to reduce factory high-RPM torque-drop with same redline. Use variable-cam timing to reduce low vs. high-end compromise.

    - 3D ignition-mapping. Don't have to compromise partial-throttle response. MC22s have retarded ignition-timing at HP-peak to reduce power.

    - yeah, EFI can get you +10% over carbs. Add that to Dave Moss's 58bhp and we're looking at 64bhp! :)
     
    Last edited: Jul 26, 2020
  2. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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  3. DannoXYZ

    DannoXYZ Active Member

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    Yup, 48.93 hp at rear wheels is about 57.5 bhp at crank.

    Note that there's 30% drop in torque from peak to redline. If torque can be held high to redline, you're looking at 30% more power without needing to raise redline. As mentioned, it could be ignition that's insufficient at high-RPM, or dropping slides in carbs, or dropping VE.
     
  4. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Torque drops because the cylinder heads cannot flow that amount, the end. It has nothing to do with ignition timing or carburetor parts. Manufacturers are not easing back the ignition advance to lose power. Early model 250's were not restricted. When that happened the power dropped to 40hp.
     
  5. kiffsta

    kiffsta Administrator Staff Member Dirty Wheel Club Contributing Member

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    I am just happy that the high revving in line 4’s are back , I can’t wait to see them on the track replacing the ninja 300/400 and r3’s in proddy racing , a grid full on thee bikes will make for some good battles .

    Come on Yamaha , Honda and Suzuki
     
  6. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    I'm pretty sure Hp loss to the back wheel is around 5% to 10% on a motorcycle
     
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  7. DannoXYZ

    DannoXYZ Active Member

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    From hundreds of dyno-tests I've done, they've all been 13-18% losses compared to crank bhp. From chart you posted on Dave's bike:
    [​IMG]
    Baseline 35.58hp at wheels is 21% loss compared to factory 45bhp for MC19. Actual crank-HP is probably closer to 42bhp due to being race-bike engine needing rebuild, which is 15% loss.

    Look at Yamaha R3
    https://en.wikipedia.org/wiki/Yamaha_YZF-R3
    https://www.cycleworld.com/2015/05/...orcycle-dyno-run-video-and-performance-chart/
    Getting 36.7hp at wheels is 13% loss from Yamaha's 42hp figures.

    Did about 30 dyno-runs over course of 2-years getting my 09 Ninja 250R dialed in.
    [​IMG]
    Baseline 25.32hp is 15% loss from Kawi crank figure of 29.9hp.

    My '08 CBR600RR has 118bhp from factory. On dyno with K&N filter it gets 102.8 which is about ~2bhp over stock. This is 13% loss using higher rwhp figure, closer to 15% loss using more common 100hp figure.
    [​IMG]

    Here's stock 2009 CBR600RR when it came out in comparison to previous 2008 with PC Ignition module mods. Getting 97.7 rwhp is 19% loss compared to published 120bhp @ crank.

    [​IMG]

    It was suspected that Honda crippled this bike with insufficient ignition advance in upper-RPMs. Dialing in couple more degrees ignition in WOT upper-RPMs gained back significant amounts of torque and power. About 6bhp over stock 2008 CBR600RR.
     
    Last edited: Jul 27, 2020
  8. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Claimed factory horsepower figures need to be taken with a grain of salt. As for the 'at the crank' idea, when I see a motorcycle engine with its crankshaft bolted to a dyno then I will believe it. Until then it is just speculation. Honda do not 'cripple' their engines. They are designed by engineers to have the maximum power output with a suitable safety margin to allow for ambient conditions, fuel quality and so on. These are road engines not race engines. Is it possible that gains can be made by squeezing that margin, absolutely. And you have done a good job @DannoXYZ of doing just that in tuning your bikes. Kudos for that. But please do not post that this is a fact and that is a fact. From your posts I would say that rear wheel horsepower figures from a Dynojet rolling road dyno can be expected to be 13% to 15% lower than factory claimed figures.

    Akrapovic use a SuperFlo dyno which, to the best of my knowledge, always shows lower hp numbers than Dynojet. Does this mean that Dynojet are bad? Absolutely not, but it does tell us to be skeptical of numbers from different sources. What is important is the improvements shown on the same dyno, like your Ninja 250.
    akrapovic-2020-kawasaki-ninja-zx-25r-horsepower-specs-3.jpg

    This chart was accidentally leaked by Akrapovic. This company does exhausts for the factory MotoGP bikes. They have credibility. Does this mean that the ZX-25R is a gutless pile of junk that will get thrashed by an MC22? I would say not a chance in hell. When you see a dyno chart done by Akrapovic using the same dyno on an MC22 then you can compare. Until then it is pointless.
    Cheers
    Blair
     
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  9. DannoXYZ

    DannoXYZ Active Member

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    With amount of public scrutiny any major manufacturer faces, I doubt they lie about their engine's outputs. If anything, they may understate the figures to sandbag their competitors (MKV Supra being one example). My main background has been in autos, had tuning-shop upgrading Porsche Turbos for about 10-years decades ago. I cracked Motronic code about 25-yrs ago and was able to extract +100bhp from 251bhp engine using software-upgrade alone. I find it fascinating that they all have some sort of trickery or easter-eggs in their ECUs; witness VW's recent debacle.

    I completely agree with you that power at wheels is ultimately what matters. That takes into account wear & tear of all components. Heck, even worn dry chain will suck up lots of power. Which is why G-Force's use of cryo-treatment matters so much.

    Dave Moss's bike has always been subject of rumors and debate since it's such rare item in U.S. Dave's great rider of course, always in top-5. His times are always slightly faster than similar riders on similarly-powered bikes such as FZR400, CBR400RR/VFR400RR, EX500. All have roughly 57-61bhp and puts down 50-51hp at rear wheel. His slightly lower power of 49hp, but adding in 22kg lighter advantage of CBR250RR could explain those couple of seconds.

    It's fascinating for me as they've done away with 250-classes this year and lumped them all into 350-Superbike. My Ninja 250R won't be competitive with ~20hp disadvantage going up against Dave. So I started looking at ZX-25R. My friend Yukaru put $5K down at dealer for advanced purchase of one. Luckily, actual pricing is lower than earlier predictions. But when ZX-25R came out so, so much heavier than earlier ZXR-250s, I had to look elsewhere. Similar CBR250RR to Dave's may be my answer.

    Would be very fascinating to see how ZX-25Rs compares to MC19/22s on track once people start racing them!!! :)
     
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  10. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    I was doing a bit of reading about car dyno's and depending on what gearbox and diff it was running they had a 15
    % to 25% hp drop at the rear wheel's
    This was from a guy that had his own dyno shop.
    Lingenfelter Performance Engineering

    I can't see there being that much loss from the engine to the rear wheel on a motorcycle
     
  11. DannoXYZ

    DannoXYZ Active Member

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    Yeah, I saw some muscle-car comparisons at Lingenfelter and results were astonishing. I think Camaro or Firebird had highest drive-train losses at ~30%.

    Thing with drive-train losses has to do with amount of load and contact area. A 600 SuperSport puts out as much power as Toyota Corolla. But it has to transmit that same power through much, much smaller parts with much smaller contact area.

    Imagine stack of 5-6 bricks with rope on bottom. Then you drag it across floor at 1-m/s. There's a certain amount of friction and heat generated. Now imagine placing that same stack of bricks on small 1x1cm brick and dragging entire stack across floor at 2-m/s. In 2nd example, you're gonna have a lot more friction as that small brick digs in when you drag it faster right? You can also measure different wear-rates on mating surfaces after 100 drags across floor. Smaller parts at higher RPMs experience more friction when forced to transmit same loads as larger parts at lower RPMs.

    Oil also comes into play as bikes must share oil between transmission and engine. Oil can't be too slippery or you'll have clutch-slippage. Moto oils are nowhere nearly as slippery as hypoid GL-5 gear oils. So those smaller gears in bike-transmission ends up not as efficient at transmitting power compared to car's transmission for same power-output.

    Another example may be comparing tyre-sizes for same 120bhp output. Smaller tyres will get shredded while larger ones survive.

    Speaking of tyres, curved profile of moto tyres results in more deflection at contact patch and more heat generated. Feel bike's tyre after dyno-run and it's definitely hotter than car-tyres.

    Then there's chain which is 98% efficient in best of conditions. Add in some wear & tear and it loses even more. Racers and moto-crossers use chains without seals because O-ring drag also saps a little bit of power. Larger front-sprockets lose less than small ones due to amount of bending of each link as it wraps around.

    So all little bits of friction here and there results in ~12-18% power-loss from crank to rear-wheel. It's still less than cars for sure. In my experience and others' testing, it comes out to 12-18% and I just use 15% as kinda average or median value.
     
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    Last edited: Jul 29, 2020
  12. DannoXYZ

    DannoXYZ Active Member

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    BTW - I use 18-20% for cars with FWD being slightly more efficient due to lower power, ligher drivetrain (fewer parts) and lack of 90-degree bevel gear. Even so, in Lingenfelter's tests, Corvette and Porsche ended up being most efficient at 15%. Not typical though as I think those cars had extra attention on drivetrain efficiency. Forged and extra polished 1st & 2nd gears, sintered synchros, etc.
     
    Last edited: Jul 29, 2020
  13. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Just recently I did read that it's ~ up to 20% from crank to tyre on a bike, the information was credible, but I don't recall where I read it for reference so I won't jump up and down and say you have to believe me
    Memory neurons just fired, it was related to the different possible drive trains on a bike, chain drive, belt drive and shaft drive

    https://www.custom-choppers-guide.com/chain-vs-belt-vs-shaft.html

    Doesn't detail the transmission losses through the gearbox though
     
  14. Andych

    Andych Senior Member Premium Member

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    I think this is all.... :offtopic:
     
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  15. jmw76

    jmw76 Well-Known Member Premium Member

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    Yes, maybe there is a need for new thread that focuses on power expectations/achievements for various 250s. There seems to be some interest.
     
  16. DannoXYZ

    DannoXYZ Active Member

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  17. DannoXYZ

    DannoXYZ Active Member

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    I actually know someone in Indonesia. Let me ask him to test-ride one..
     
  18. Mastroragno

    Mastroragno Member Premium Member

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    180kg? :( In any case I don't think we'll ever see it in Europe, due our restrictions...
     
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  19. DannoXYZ

    DannoXYZ Active Member

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    What kind of restrictions? Emissions and noise?
     
  20. Mastroragno

    Mastroragno Member Premium Member

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    Both, but especially for emissions...
     

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