Installing Mikuni carbs

Discussion in 'Airheads' started by mrbindc, Dec 7, 2012.

  1. mrbindc

    mrbindc Adventurer

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    I took the leap and ordered up the Mikuni carb kit from Rocky Point Cycle. The old Bings were in need of a rebuild, which I am planning to do, but I thought I'd try out the RPC kit for a comparison. The difference in the colour of the floats in the Bings was interesting.


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    The Mikuni carbs are very slick, I like how the RCP kit uses two different models so you can set them up with the idle screws on the outside. RCP recommends soaking the rubber connectors in hot water to make the installation easier. After a soak they went on without any drama.

    I think I may just JB weld them to the rubber connectors instead of using the clamps... :D



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    #1
  2. oldroadie

    oldroadie Two wheel addict

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    Do yourself a favor and pull the choke(enrichner) valves out and give them a shot of silicon lube. Keeps them from hanging up and giving you false plug readings. Took me a while to figure that one out...
    #2
  3. photorider

    photorider Been here awhile

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    Well? How do you like 'em?
    #3
  4. hardwaregrrl

    hardwaregrrl ignore list

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    Another Mikuni convert!!!!:freaky
    #4
  5. disston

    disston ShadeTreeExpert

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    Those look like nice carburetors.
    #5
  6. mendoje

    mendoje Been here awhile

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    Subscribed! I've been thinking about doing this too.

    What bike is this on? (Edit: I checked your profile, an R65?) Do they come jetted for your bike? How's it run?
    #6
  7. Beater

    Beater The Bavarian Butcher

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    I love my Mikunis. I will be putting them on my GS when the cash presents itself. Dead simple, reliable, no diaphram, and the parts are widely available. Better throttle response ... about the same milage. Me likes.
    #7
  8. mrbindc

    mrbindc Adventurer

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    Sorry for the delay, work was taking up too much time so I couldn't tinker last week... Nice to have a job but when it gets in the way of tinker time, frustrating...

    Anyway, back to the fun. The Mikuni carbs are on a 1982 R65, my Frankenbeemer with the K75 front end.

    The bike fired right up, I still need to dial them in a bit and adjust the cables but the installation was pretty straight forward. Now all I need is Charlie to stop by sometime and show me how to tune them by ear. :D

    I ended up using a couple of my OEM hose clamps. The clamps provided in the kit are decent but a couple of them seemed to be defective. The flat blade screwdriver slot on the head wasn't stamped through enough to get a good bite, I could have made them work with some effort but I said eff it and used my OEM clamps.

    btw, I was kidding about the JB weld...

    PS, the rear secton of the front fender is off the bike for painting.

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    #8
  9. oldroadie

    oldroadie Two wheel addict

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    You'll find the air mix screw hard to get to on the left carb. I've been using a bit from a screwdriver set for that (you can count the flats as you turn between your finger tips).
    #9
  10. hardwaregrrl

    hardwaregrrl ignore list

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    So sync them with a drill bit. Here's how....warm the bike up. I ride for about 15 mins. Then pop the carb elbows off. Grab a bunch of small drill bits. Insert the no business end in the back of the carb until it barely slides under the slide at a 90degree angle, I think i use a 3/16" so have several sizes at the ready. Then take the right size bit to the other side and using the throttle adjust screw, adjust the other side to be the same. It works much better that adjusting on the fly. Then if you need to bump the idle up or down, just make sure to turn the screws the same.

    On the air screw i find it easier to take the carb off to adjust.
    #10
  11. dvblue_2000

    dvblue_2000 Probationary

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    I had that problem. I had fits tuning this thing and getting it to idle before I figured out. I push the little plungers down with my finger each time I use the chokes.
    #11
  12. Kai Ju

    Kai Ju Long timer

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    Silver solder or braze a one inch extension to the airscrew and cut a screwdriver slot in the end so you have a reference on the number of turns.Then slip a piece of vacuum tube over the extension. Now you can adjust it by reaching up from under the float bowl, no need to remove the carb.
    I'm also using the stock clamshell airbox and adapted the stock choke actuating mechanism to the Mikunis, beats having to turn the chokes off individually.
    #12
  13. mrbindc

    mrbindc Adventurer

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    RPC sells a choke adapter kit for the Mikunis. I haven't bought it but I'm wondering how did you make your stock cables work for the choke?
    #13
  14. Rapid Dog

    Rapid Dog bikes, booze, broads...

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    what size Miks did you buy?
    #14
  15. Kai Ju

    Kai Ju Long timer

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    I didn't use the stock cables. I made my own out of a couple of throttle cables I already had.
    Since the Mikuni choke plunger is spring loaded I didn't need the single wire cable to push the mechanism closed like the Bings do.
    #15
  16. Uncle Pollo

    Uncle Pollo Long timer

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    Bazinga!
    #16
  17. mrbindc

    mrbindc Adventurer

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    I have the 32mm VM kit from RPC. After reading the manual online, I guess I shouldn't call it a choke even thought the word "choke" is stamped on the lever. They call it a starting system. Very fancy! :D
    #17
  18. disston

    disston ShadeTreeExpert

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    If the starting system restricts the flow of air to make the fuel mix richer then it is a choke.
    #18
  19. Uncle Pollo

    Uncle Pollo Long timer

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    I throttle myself everytime I read "choke" on the lever.
    #19
  20. mrbindc

    mrbindc Adventurer

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    "I throttle myself everytime I read "choke" on the lever."


    oh brother...
    #20