Mikuni on an R80 help

Discussion in 'Airheads' started by hardwaregrrl, Sep 6, 2012.

  1. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    Not sure if a color tune will fit in plugs, but using one of those will let you see the spark and then you can tune by color of the spark, a bunsen blue is just about right, orange is to rich.
    #61
  2. Les_Garten

    Les_Garten Been here awhile

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    Isn't it dangerous getting your head down there while you're driving down the road?

    :wink:
    #62
  3. Les_Garten

    Les_Garten Been here awhile

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    I was wondering about this as well last night.

    I have HS40's on mine, as well as some RS40's.

    The difference is the addition of an R, for instance:

    So an HS with rollers is an HSR

    A TM with Rollers is a TMR

    You would most likely be interested in TMR's. The HSR's start at 42mm, they're Hawg Carburettors
    #63
  4. Stagehand

    Stagehand Imperfectionist

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    TMR.. Arr arrr good to know, thank you. I heard hearsay they were easily twice as expensive (like 800USD/pair) but didnt rub themselves raw, and wear out the body.
    #64
  5. Les_Garten

    Les_Garten Been here awhile

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    Rubbing themselves raw... Don't tease me!

    Not to mention, at least for the HS's, that the freakin throttle springs are monsters to hold.
    #65
  6. Airhead Wrangler

    Airhead Wrangler Long timer

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    Same for the VMs I'm using. I only managed to hook up one of them so far and it's already equal to the pull effort of both bings. The addition of the second carb could prove too much. It could also have to do with the Venhill throttle grip I'm using though.
    #66
  7. Les_Garten

    Les_Garten Been here awhile

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    I don't know much about VM's, but the HS's and RS's have 3 positions for the throttle spring. They come set for the heaviest spring position. Moving them to the lightest position helps a ton. Let us know if the VM's are like that as well. Hopefully this will give your right hand a little break, won't be no Sunny day at the beach though.
    #67
  8. Airhead Wrangler

    Airhead Wrangler Long timer

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    VMs don't have that option. Only one place for the spring to go: inside.
    #68
  9. Les_Garten

    Les_Garten Been here awhile

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    That's too bad, I feel your pain.
    #69
  10. RGregor

    RGregor Been here awhile

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    For Dellortos three different springs are available. Any chance that Mikuni has softer springs available?
    If you give me the dimensions of your springs I could check with the Dello springs.
    #70
  11. Kai Ju

    Kai Ju Long timer

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    I don't understand why you have a hard throttle pull.
    My VM 38s are a lot easier to pull than the Bings. Mind you, I did make my own throttle cam, or I should say that I modified the stock /7 cam to allow the throttle to fully open.
    What kind of throttle are you using ?
    #71
  12. Airhead Wrangler

    Airhead Wrangler Long timer

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    That's entirely possible. I haven't checked yet. I appreciate the offer, but I can't measure them at the moment because they're with my bike up in Seattle. I'm down in Mexico. Sorry.
    #72
  13. Les_Garten

    Les_Garten Been here awhile

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    Sorry to participate in derailing the thread. Just one more throttle spring post.

    I went to these guys a few minutes ago and they'll make me some custom springs for my Mikunis.

    http://www.springsfast.com/custom.php

    p.s. I will put some input into the OP though.

    Not sure why you are so resistant to the AFR gauge. I had a colortune at some point and found it pretty useless for tuning, other than maybe idle mix.

    You could find one(Innovate AFR) for a good price used on Fleaby. Use it to "PERFECTLY" tune your bike and sell for probably what you have in it and use it for practically free.

    Innovate is the one you want.

    They have a tail pipe sniffer, which may work on your bike. I would weld a SS bung in my headers, but the sniffer may work for you depending on the exhaust you have. Then you would have the Best HP and the Best Gas mileage. You wouldn't leave anything on the table.

    I would think with those 32's, you would have killer stump pulling torque and awesome mpg if done right.
    #73
  14. Uncle Pollo

    Uncle Pollo Long timer

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    Mine are soft.
    #74
  15. Airhead Wrangler

    Airhead Wrangler Long timer

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    Hmm. Maybe I hooked up the throttle using the 'fast action' side of the cam rather than the normal side. I'll have to check it again.

    EDIT: I checked the specs and the thottle takes up 36mm of cable in either 68 or 80 degrees of rotation depending on which setting you use. I'm not sure how that compares to the stock BMW throttle though.
    #75
  16. hardwaregrrl

    hardwaregrrl ignore list

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    Not opposed, never said I was. Nathan had one when he was a ducati dealer. I may have the bike dynoed at HD, or check to see if they have an AFR gauge. I'm currently not working so I don't have cash to throw at this bike or I would purchase one.
    #76
  17. RGregor

    RGregor Been here awhile

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    Just in case: the dello springs have an outer diameter of 20mm, length is 125 and135 mm (stiffer ones are longer)
    #77
  18. Les_Garten

    Les_Garten Been here awhile

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    Gotcha.


    The price of the Dyno is going to be a good portion of the price of the gauge methinks.
    #78
  19. tradern

    tradern Toowoomba QLD

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    You can cut the slide springs to ease the hard pull on the mikuni's. I've progressively taken almost 3cm off to great effect. This is using an MX aftermarket throttle (specifically a 2 stroke domino model). Thanks go to Mr. Rooney for this tip.
    #79
  20. Les_Garten

    Les_Garten Been here awhile

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    I was just talking to a guy about this as well.

    Here's a kewl video of some Yoshimura modified TMR carbs.

    They are called MJN mods for multi jet nozzle.

    The needle is hollow and acts as a spray bar or like an emulsion tube. Very freakin' expensive.

    http://www.youtube.com/watch?v=APq5jz4T_08
    #80