Honda CRF1000L AFRICA TWIN merged threadfest

Discussion in 'Land of the Rising Sun: ADV Bikes from Japan' started by dwestly, May 12, 2015.

  1. mcmann

    mcmann Motorcycle ADV enthusiast

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    The simple rule of thumb is 3% hp loss per thousand feet.

    If you want to get precise, you can first calculate your Density Altitude by using local existing temperature and barometric pressure, then do the 3% from that.

    http://www.wallaceracing.com/braking-hp.php

    Your BHP loss computed from your BHP of 90 at sea level and Elevation of 8000 feet is 21.60 HP loss.
    windowto likes this.
  2. MarshkevUK

    MarshkevUK Alright Guv'na?

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    Has something made a nest in your filter box?
    Seems strange to me that you're having those issues on a fuel injected bike as the fuel map and o2 sensors should take care of that.
    Ive ridden up at 12000' on several occasions and I've never noticed the type of performance loss you're describing.

    MK.

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  3. windowto

    windowto Long timer

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    If I say the obvious, please forgive me, but fuel injection corrections only compensate for fuel/air mixture. There is no compensation for losing atmospheric pressure. What I'm saying is that, unless the engine is turbocharged (which this one is not), you will lose power with altitude, a lot of power. Even airplanes lose power at higher airports. You still have the correct fuel/air mixture, but much less power.

    A couple of years ago I rented a Tiger 800, in Colorado, and it felt like a 650.

    Anyway, the engine should regain the power when you go to lower altitude. If it, doesn't, you might have a real problem...

    From your description it sounds like you didn't regain the power back, so... Could be.

    But fuel injection will not presevere your sea level performance.

    Again, forgive me if you already knew that:)
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  4. MarshkevUK

    MarshkevUK Alright Guv'na?

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    Treading on v. thin ground here because you're obviously pretty knowledgable on the subject but isn't it true that ambient air temperature also has a part to play in the equation?
    I.E. High and hot equates to an even higher altitude whereas high and cold might equate to a lower one than reality, i think it's called density altitude or something? So an 8000' alt. and 100f temp probably resulted in a density altitude of closer to 12'000 or so...

    While i'd agree that there will definitely be a loss of of effective HP if everything was working as advertised wouldn't the FI system adjust the fuel/air ratio to a degree and somewhat mitigate/mask that loss in performance?

    That being the case i'd agree that the perfomance issues Chr15lawson is describing cannot just atributed to engine performance alone.

    MK.
  5. windowto

    windowto Long timer

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    Well, you are correct that temperature has a lot to do with performance. You are correct that higher temperature increases the density altitude... However, the FI cannot replace the lack of air density, all it can do is reduce fuel to match the reduced air mass. I say mass because the volume stays constant but, in reality, less air molecules get in the cylinder due to lower air density. Less air requires less fuel to match, that's where the FI makes the adjustment, but again, it cannot replace the lost air.

    And so, less air, equals less power. Higher temperatures make the air even thinner, which means less air in the cylinder. Less air, less...

    You got the point:)
    MarshkevUK and Nikoutdoor like this.
  6. michaeln

    michaeln What're YOU lookin' at?

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    Mine is a dog at 6000-9000 feet. FI or not there is still a lot less O2 up there.
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  7. chrshale01

    chrshale01 Adventurer

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    Indeed.

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  8. neanderthal

    neanderthal globeriding wannabe

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    Maybe something shook itself loose? A sensor or something?!?!
  9. Chr15lawson

    Chr15lawson Adventurer

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    Thanks for the replies guys. Just rolled over 5000 miles. Down in Salt Lake for the evening (actually morning). Much much better performance. Feels back to normal. I'm going with bad gas and altitude as I can't believe the bike performed so poorly at 8000 feet. Now mind you it was 100 degrees and it was humid as there were warm showers, but still! I've driven new and old cars from Durban to Johannesburg and not noticed as much of a performance difference and these were all sub 1.6 liter compacts. To give more info for info sake, I am 170lbs and with gear let's call it 190. I have 80lbs of gear on the back in a Moskomoto reckless 80 system including fuel and water. I also have a small duffel on an altrider tail peice. It has a skid plate and engine guards which add a few lbs. If it was just altitude just be aware for those of you who have not climbed yet. It wasn't bad by any means but it was concerning enough to post this message and it made me think twice about passing up hill without first being double sure I had more than enough room. Like I said it would get to 90 but much much slower and without the front end lifting and throwing you back.

    Anyways. The issue now is tires (mefo super explorers are toast) and a clutch lever or linkage adjustment? I'm getting a few grinds from 2nd to 1st. Never had this issue on hydraulic clutches. Either way it's running great and it will go in for it's 8000 service at around 6500 and get new fluids and a filter. It may be premature from the manual but in 18 days it's been run hard from coastal windies (forks Washington to San Francisco), lane split in hours of 100 degree heat from SF to Sacramento and then screamed from Reno to Moab. Got a bit dusty in Moab and now it's going up the Saw Tooths before returning home.

    Have some AT porn for your excellent replies.

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    Jersey Dave, Stromcat, gammel and 4 others like this.
  10. jyrays

    jyrays The Wanderer

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    I have been up to 2780 meters, had no problems...
  11. wheatwhacker

    wheatwhacker It's raining here

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    Just did the wheel swop. Both bike look way better.
    [​IMG][​IMG]


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    No Degree, 1litre, EBR458 and 6 others like this.
  12. michaeln

    michaeln What're YOU lookin' at?

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    Looks great, Martin!
  13. CrStep

    CrStep Been here awhile

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    I wouldn't mind some gold rims on my red one. I think I could pull it off :big pimpin
  14. neanderthal

    neanderthal globeriding wannabe

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    Those black bikes look niiiiiiiiiiiiiiiiiiiiiiiiiice! :drif
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  15. grondpaaie

    grondpaaie Never too Old to Ride

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  16. Chr15lawson

    Chr15lawson Adventurer

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    When the Italians accept the Japanese bike. Must be a twin thing.

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  17. Tinker07

    Tinker07 Adventurer

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    Looks great but only because you're from Cork !!!! County Louth here !!
    wheatwhacker likes this.
  18. Trialsguy

    Trialsguy Been here awhile

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    I'd love to swap gold rims on to my red bike, but there doesn't seem to be many white-bike owners out there pining for black rims.
  19. doctord23

    doctord23 Adventurer

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    I like the looks of the black rims on the white AT.
  20. Drif10

    Drif10 Accredited Jackass

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    Not any more...

    :augie
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