New air box

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by tahoeacr, Feb 3, 2012.

  1. Johnf3

    Johnf3 Long timer

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    Hi MotoTex,
    I would say the fuel mileage is about the same, possibly slightly better with the CPR set up. The best I have done is about 43 mpg coming back from Cloudcroft. Mostly my mileage is mid 30's, but I am a poor example because on our straight flat no- traffic West Texas roads I am normally flogging the poor girl to get to the good dirt quicker.
  2. MotoTex

    MotoTex Miles of Smiles

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    Man, I have dreams of seeing 43. 33-34 seems to be the norm.

    Of course it IS downhill from Cloudcroft to Presidio County, so I guess that accounts for the better smileage. :D

    As long as it didn't lose any mileage per tank the CPR is looking pretty nice.

    Thanks!
  3. AdvRonski

    AdvRonski They call me......Ronski

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    I'm wondering if anyone can compare the Adventure Machines jetting kit, which I believe uses Factory Pro needles, to the 175/180 stock needles setup. Obviously, there is a huge gain with the Rottweiler airbox, but what kind of performance increase is there with Ken's jetting?
  4. Johnf3

    Johnf3 Long timer

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    ...and I had a 20 mph dead from the west tail wind. Probably need to throw that result out. Set up right I don't think you will lose any mileage. I have a few K on my set up without any negative results.
  5. AJ990R

    AJ990R motorcycle guy

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    From what I've gathered, my 11' 990R adv w/akra map & exh(with or w/out db killers) is a decent enough baseline to run/flog my bike w/the CPR? Not interested in spending a lot of time & $ in tuning it. Don't want run her too lean either. But shit $300 for 5hp on a bike, sign me up! thanks

    AJ
  6. pdxmotorhead

    pdxmotorhead Been here awhile

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    Just thought I'd kick in some experience on these style filters...

    I use the same manufacturer filter on a twin cam Cosworth engine... Just 2 more velocity stacks.. :)

    None of the pictures of the filters I've seen on this thread are anywhere near as dirty as we get them on the track.
    They are really tolerant of dirt..

    Always use grease on the sealing surface, nasty thick grease. I use red-line wheel bearing grease.

    We found on the midget would have lean out problems and the fix was to put a aluminum dam around the front of the filter. About 1" away.

    If you dyno a engine with velocity stacks you'll see an interesting effect, its called a fuel fog column, it will extend 1 to 2 inches above the velocity stack. (The dyno operator is world class and had lots of experience with formula engines... ) With the engine under power if air blows across the top of the stacks the mixture goes crazy. He demonstrated with the hose from a shop vacume. I suspect if you put a air dam in front of the filter so the air coming through the body work enters the filter form the sides but cant come straight in it will help keep the buffeting down..

    Short stacks for RPM & HP long stacks for low end grunt and torque.

    Cheers
    Dave
  7. rossguzzi

    rossguzzi 990 Adv.

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    Thanks Dave for that info. It could be what is going on with my bike. When I get gusts of wind, side or head on, it feels like the mixture goes haywire.
    I remember many years ago on my Moto Morini 3 1/2 sport with k&n filter pods, it had the same symptoms. Good in clean air, bad in side/front on buffeting winds.
    I have been thinking it may be the carb breather tubes doing something strange to float level. The reason is that it was doing this when I had the airbox and prefilter on it too.
    I may try to knock up some sort of dam or buffer out of cardboard first to see.
    Cheers.
  8. Spark01

    Spark01 V-Twin

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    thanks that inside, but i would suspect if we put a "airdam" in front of the filter. then the most air comes from below and then we are sucking hot air due to the heat of the engine. and that doesn't help for power. however if we put a plate beneath the filter so no hot air can come from that way and a airdam in front of the filter then maybe it would work....?. (cold air enters from behind in the airbox)


    p.s do you mean such kind of mist above the stacks like in this video: http://www.youtube.com/watch?v=y2iBbwocYZw
  9. rossguzzi

    rossguzzi 990 Adv.

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    Well I fitted a cardboard dam in front of the filter and it has fixed the problem I was getting of weird fueling at gusting head/side winds. Now to make a proper plastic one. Thanks Dave.

    Very happy !
  10. pdxmotorhead

    pdxmotorhead Been here awhile

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    Yep that's it, and you don't need high injectors for it, it even happens with 48IDA webbers.

    I would suspect that its just a matter of making the air tumble a bit so you don't have laminar flow slicing across the top of the velocity stacks.. ( Just my gut on this one... :) )

    You might even be able to just put a piece of denser foam just on the front of the filter so the air comes more from the sides but is not totally blocked? Aero is always 1/2 science 1/2 voodoo.

    Dave
  11. rossguzzi

    rossguzzi 990 Adv.

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    I have not had time to make the plastic copy of the cardboard air dam yet. But the bike seems to be running real good. BUT I am also wondering if I can use longer stacks than the cut down jobs I got with the CRP unit. I like mid range over top end grunt. The ones I got with the kit are just over 1 inch or 28mm long versus stock ones, 50mm or 2 inchs long.
    I tried to fit the 50mm ones but they foul with the filter. Anyone know the max length you can install?
    Cheers
  12. randel

    randel Been here awhile

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    ITG says minimum clearance between filter and intake trumpet must be at least 19mm, preferably 30mm. So if it is 65mm filter, max you should use is 46mm.
    Source: ITG Air Filters
  13. pdxmotorhead

    pdxmotorhead Been here awhile

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    Here is a picture of what we did on the midget, the filter is sitting similar to the way it would be on the engine..
    The car does between 80 and 100 on track, and as the filter is on the right side it takes a lot of air blast..



    http://www.flickr.com/photos/33629139@N08/8419484532/in/photostream

    First time trying this,, :)

    BTW ITG is right, if you get the stacks too close to the filter you'll see wet spots on the media..

    Dave