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Thread: mikuni conversion

  1. #1
    Red1974
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    mikuni conversion

    Hi folks....Searched but could'nt find anything. What are the pros and cons of the Mikuni carb conversion for an R90/6? Heck on ebay theres a kit for 250ish plus 78 for the cables. I can hardly rebuild my Bings for the price of new Mikunis. So whats you alls considered opinions on this? Thanks Red1974

  2. #2
    Liaison 20774's Avatar
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    Stan at Rocky Point Cycles (http://www.rockypointcycle.com/) has new kits for $400ish...not sure about cables.

    I'm sure it would work fine...would give you more snap when you twist the grip but you would loose some of the "smoothness" of the Bing CVs. The Bings tend to blend across the throttle regimes better and also self-adjust when traveling to and from diffirent altitudes regions.
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    --Tony AnnapolisAirhead's Avatar
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    Quote Originally Posted by Red1974 View Post
    I can hardly rebuild my Bings for the price of new Mikunis. So whats you alls considered opinions on this? Thanks Red1974
    Huh? Bings are pretty cheap to rebuild...certainly less than $300-400 Mikunis. Worst case you'd be into about $80 for rebuild kits with diaphrams, o-rings, gaskets, etc. eubmw.com has good prices on rebuilt kits. Are your carbs trashed now?

    Even if you needed new floats and needles, you'd be in pretty good shape and have OEM carbs. I've heard the Mikuni conversions from Rocky Point are a simple switch and some really like them, but the Bings just seem to fit and do the job for me.
    1971 BMW R75/5 | 1975 Moto Guzzi 850T Cafe | 1983 BMW R100RS | 1988 BMW R100GS
    1988 BMW K75 | 1998 BWM R1100RT | 2000 Moto Guzzi Quota 1100ES |2002 Moto Guzzi V11 LeMans

  4. #4
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    I am speaking out of my butt here because I havre never done this conversion, BUT when converting British cars with Su's and Strombergs to Weber carburetors, I wuz an expert. The percieved throttle response advantage of many correctly tuned carbs is only when the car was at idle and the driver was blipping the throttle going vroom vroom. The supposed throttle response disadvantage of the Stromberg and SU's (similar design to Bings) did not occur under load. However, the Webers were a lot easier to tune correctly, a great help when modifying engines. The Bing style carbs also have slides that muffle the intake sound when you open the throttle, making the Dellortos sound better as they give the sound waves a wide open path to the ear.

    In short, if you are modifying the bike, the Mikunis make a lot of sense. If the bike is going to remain stock, the Bing's will work just as good, even though they may not be as entertaining.

  5. #5
    Registered User Rinty's Avatar
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    ...couldn't find anything...red1974
    Do an advanced search under the word "mikunis", restricting it to airheads, and you'll pull up 23 threads.
    Rinty

  6. #6

    Thumbs up

    Quote Originally Posted by Red1974 View Post
    Hi folks....Searched but could'nt find anything. What are the pros and cons of the Mikuni carb conversion for an R90/6? Heck on ebay theres a kit for 250ish plus 78 for the cables. I can hardly rebuild my Bings for the price of new Mikunis. So whats you alls considered opinions on this? Thanks Red1974
    Hi Red -

    Did a Mikuni conversion on my 1975 R-90/6 (San Jose BMW) 24 years/80K miles ago, and highly recommend it. Reliable, easy to adjust and dial-in for whatever altitude, and better performance, what more can I say?

    Also, have had no hassles with my Dell 'Orto carburetors on my R-90S, other than modifying the "goose neck" tube on the top to prevent binding of the throttle cable.

    Good luck with whatever your decison....

    J.K.

  7. #7
    Registered User DonTom's Avatar
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    Quote Originally Posted by AnnapolisAirhead View Post
    71 R75/5 SWB
    I own a 1971 BMW R75/5 also (I purchased it new in 71 and still own it). What do you use for carbs on it? The stock 71 carbs were such junk. No idle when warm. I put on Mikuni's many years ago and that solved all my carb problems.

    I don't see how anybody could tolerate the 71 Bings, so I assume you are using something other than the original Bings on your 71.

    -Don- SSF, CA

  8. #8
    Registered User DonTom's Avatar
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    Quote Originally Posted by JK View Post
    Hi Red -

    Did a Mikuni conversion on my 1975 R-90/6 (San Jose BMW) 24 years/80K miles ago, and highly recommend it. Reliable, easy to adjust and dial-in for whatever altitude, and better performance, what more can I say?
    My Mikuni's came from SJ BMW as well, perhaps around then too. What is that about the dial-in altitude? My Mikuni carbs are VM32's. Fairly easy to change the main jet, but no dial-in stuff. What type of Mikuni's do you have on yours?

    -Don- SSF, CA

  9. #9
    Barback King rapiddog's Avatar
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    Question

    I'm considering VM38s for my RS. But I can't find any info on what to do about the cables...?
    "...the burble of my exhaust unwound like a long cord behind me. Soon my speed snapped it, and I heard only the cry of the wind...." Larry of Arubia

  10. #10
    Registered User DonTom's Avatar
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    Quote Originally Posted by RAPIDDOG View Post
    I'm considering VM38s for my RS. But I can't find any info on what to do about the cables...?
    Try here.


    -Don- SSF, CA

  11. #11
    Barback King rapiddog's Avatar
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    Thumbs up

    wow that's good info
    thanks!
    "...the burble of my exhaust unwound like a long cord behind me. Soon my speed snapped it, and I heard only the cry of the wind...." Larry of Arubia

  12. #12
    copandengr
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    Mikunis

    Here's a little known fact for you guys... Did you know that Mikunis were originally made under license from Amal? That's right.. Those notorious Amals that leaked fuel all over everything, especially if you used the tickler very much.

    When I restored my '71 Norton Commando, I went from the twin Amals to a single Mikuni.. It was a one kick starter, the carb did not leak and the bike ran perfectly. The major benefit to running one Mikuni instead of dual Amals? It is rather difficult to get one carb out of sync! I'm too old to go around like some wild eyed performance junkie.. As far as I could tell, there was no difference in power at all. I would do that conversion again in a heartbeat.
    Robin Coleman Marion, Arkansas, Retired locomotive engineer.

    "All my life I dreamed of retirement so I would have the time to play.. Retirement is here now but I'm so broke I can't afford to pay attention"!

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