Keihin 35mm Air Striker Carb Jetting

Discussion in 'Airheads' started by bgoodsoil, Mar 3, 2013.

  1. bgoodsoil

    bgoodsoil Dare to be Stupid

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    Anybody put these on an airhead that could give me some jetting advice? I'm running cylinders, pistons and heads from a '92 r100gs and a 38mm exhaust. I got this set off a 2000 something Yamaha Banshee. Getting carbs from a 2-stroke 4-wheeler to work on the G/S might be a challenge.

    The carbs are coming with the original cables and the thumb throttle. I'm going to try to rig it and at least take a trip around the block with the thumb throttle :ricky

    [​IMG]

    tags: Keihin PWK A/S flat slide mikuni tm tmx vm round slide
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  2. bgoodsoil

    bgoodsoil Dare to be Stupid

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    Oh come on. I can't be the first person to pull carbs off a 4-wheeler and try to make 'em work on a G/S. Maybe I should've pulled some off a tractor :lol3
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  3. bgoodsoil

    bgoodsoil Dare to be Stupid

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    My solution to most airhead upgrades, 'wait until AW figures it out', didn't work this time. Damnit, now I have to do it the hard way! Well, at least the forks'll be easy.
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  4. Kt-88

    Kt-88 I like everything.

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    It says race use only. That kinda guarantees fun.
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  5. bgoodsoil

    bgoodsoil Dare to be Stupid

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    Yeah but I found that pic on a Vespa website. That might be some hipster swag. They may also sell pants that are really skinny and 2 inches too short to save weight for "racing".
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  6. Kt-88

    Kt-88 I like everything.

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    When I get dedicated enough to going fast to ride a racing Vespa, I will have lost anything those pants were trying to constrict anyway.


    Jk. I'd totally race a Vespa. I'm easy.
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  7. oldroadie

    oldroadie Two wheel addict

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    Whatcha gonna use for an intake and filter? K&N pods on a Keihin 34mm CV for a similar displacement Triumph engine usually start at 145 mains and 48 pilots. I know some with unrestricted exhausts that are running 155 mains for that setup, too. That flat slide won't be the same as a butterfly throttle but it should be close enough to get you started.
    #7
  8. bgoodsoil

    bgoodsoil Dare to be Stupid

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    I'm going to try to use the stock airbox to start. I might play with pulling the snorkels off and running the filter open to see how it affects flow. I can't do that until I get it to run though.

    Thanks for the numbers. As far as I know it's coming with 48 slow jets and 160 mains. I've got a ColorTune and I'm hoping to use that to set...well everything. If I start with a 48 idle, and the spark is orange, even with the mixture all the way in, I'll go down a jet. And so on.

    That's the plan anyways. I'm still waiting to talk to Jenna to hear what she has to say about it.
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  9. Airhead Wrangler

    Airhead Wrangler Long timer

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    Sorry, boss. You're on your own on this one. :D

    Air striker. Ha. Awesome name. I vote that you leave the "racing use only" stickers on there. Not quite as cool as the "not for aircraft use" stickers that come on mikunis though.
    #9
  10. hardwaregrrl

    hardwaregrrl ignore list

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    So first lets start with what can be changed. Can you change the needle jet, jet needle, slide angle? I ended up shooting into a barrel with my needle jet size and just got incredibly lucky. Msp has a dyno and only charges 50-75$ for a run but their probe won't fit in out stock muffler so lets get the busa in there. Can you get a chart to show sizes for different machines these will work on?
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  11. bgoodsoil

    bgoodsoil Dare to be Stupid

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    Yep, it's got different slides, different needles, different needle heights, the whole 9 yards. I haven't bought any jets yet because I don't have the slightest clue even what range I'd be in. I'm not sure of the jetting that will come from the Banshee.

    They're all on 2-stroke dirtbikes. I haven't found any specs from people putting these on 4-strokes. Hopefully I didn't screw up buying them. I read a lot of people switching from the Mikunis to the Keihins on thumpertalk because they're easier to jet. Nobody said it performs any better, just simpler to tune. That's what caused me to take the risk and get these carbs. This is the website that sold me on the air strikers:

    http://motocrosshideout.com/cr250cr125-pwk-air-striker-conversion-throw-out-the-tmx/

    I've got a good guide on the carbs but I still expect this to be a long process. Really wish these had that quick release float bowl. I'm going to have to pull those bowls a thousand times.
    #11
  12. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    Brad, you gonna have to get your air filter set up first as this will affect everything you do on the carb. No point jetting the carb 1st then figuring out the air filter arrangement. No point putting the cart before the horse if you do you'll wind up in the sand.......LIKE JENNA...:huh

    My DRZ doesn't run worth a shit with out the air filter. I tore it once when cleaning and who would have thought a needle and thread would be needed in a tool kit!!!!
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  13. bgoodsoil

    bgoodsoil Dare to be Stupid

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    Oh I'm not going to run without an air filter. I'd like to try it without the snorkel some time but I'm not taking off the filter. If I drop the snorkel I'll throw an oil-soaked green pad over the top of the filter. I think some bungee cords ought to hold it down.

    I'm fully expecting to do a 'Fred Special' and hose clamp a split inner-tube around the intake boots.
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  14. oldroadie

    oldroadie Two wheel addict

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    Might as well head down to True Value now a get those Allen head replacement bolts. Sure beats stripping one of those dodgy Phillips heads.
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  15. hardwaregrrl

    hardwaregrrl ignore list

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    +1 However, if you're worried about changing the main over and over, there is a plug on the bottom that allows for access to the main. Mine is a 17mm

    There must be a compairison somewhere between Mik and Kehin jets so we can at least get you in the ball park.
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  16. oldroadie

    oldroadie Two wheel addict

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  17. bgoodsoil

    bgoodsoil Dare to be Stupid

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    You must be the king of google :clap

    Now, what do all those numbers mean? :confused
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  18. Airhead Wrangler

    Airhead Wrangler Long timer

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    Mikuni and Keihin numbers represent volumetric flow rates for a given pressure difference across the jet. Mikunis are cc/minute with 50cm of (gasoline) head pressure. Not sure on Keihin's units. Dynojet numbers are a function of hole diameter and have nothing to do with flow rate.
    #18
  19. bgoodsoil

    bgoodsoil Dare to be Stupid

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    Who needs Google :D Looking on the Mikuni thread (good idea btw) the r100s are running 190-200 mains and the slow jet is around 30. I'm not seeing those on the list. It was worth a shot at least.
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  20. Sniper X

    Sniper X De Oppresso Liber

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    Well, a Banshee is a 2 stroke and only 350cc (so 175cc per side) and since 2 strokes run so different than a 4 stroke, I am going to say this should be way fun! I am going to go out on a limb here and say slap em on and see if it'll run! What is your altitude? Close to sea level yes?
    #20