Keihin carb ugrade for the DRZ400SM
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Thread: Keihin carb ugrade for the DRZ400SM

  1. #1
    Join Date
    Nov 2010

    Default Keihin carb ugrade for the DRZ400SM

    Alright, so I've read a bunch of threads on this, but apparently not enough. Consensus seems to be that swapping the Keihin FCR-MX 39MM carb onto the DRZ is like giving it a pair of balls. Thumpertalk sells the carb and all the crap you need for $560. I was perusing fleabay the other day, and came across a Rath Racing Keihin 39MM carb with the flange to fit the DRZ for substantially cheaper. I don't know if Keihin is still selling a non-MX FCR, but I figure this can't be the case. Anyways, does this look like the MX?

  3. #2
    Join Date
    Oct 2008
    Laurel, Md


    sort of
    2007 CRF150R winter project
    2011 KTM 250XC (Woods Killer/Tree Molester )
    2001 XR 50 (Wicked cool),
    2007 CR85R mini-sumo (sold), 2008 KTM 250 SX-F (Both Dirty and Tarded' Sold), 2008 Husky 510 SMR (Sold ), 2002 CR 250R Basketcase (Sold), 2007 Suzuki DRZ 400sm (Sold)

  4. #3
    Join Date
    Apr 2008
    Franklin, NC
    Items for Sale


    Quote Originally Posted by Twatwaffle View Post
    Consensus seems to be that swapping the Keihin FCR-MX 39MM carb onto the DRZ is like giving it a pair of balls.
    Don't buy into all the hype. It's much better than the stocker for sure, but it's not the fire breathing monster mod some would lead you to believe. But, if you plan on doing any other mods down the road, you'll need it anyways. Keep in mind, you're still going to need airboots, and other small odds and ends to finish up the conversion as well.
    "Just stay in the fast lane, and keep moving, you cannot predict your final day, so go hard for the good times while you can." Kenny Stabler
    '08 DRZ 400sm - FCR, E cams, SSW / MRD, Tuned by Wheeler
    '02 XR 50 - 1/4 scale stunt bike

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  6. #4
    Join Date
    May 2008
    Western Mass


    HPI is right. While an FCR makes a noticeable difference, your DRZ isn't going to become a KTM. While I'm not sure if that particular carb will work, you can get the remaining adapters from like I did.
    HPI, how much do the cams and the flywheel help? I'd like to upgrade a little more, but not get into a BB kit yet. ($$ reasons)
    Sorry for the threadjack.

  7. #5
    Join Date
    Mar 2006
    North Dallas Texas


    I have one just like that. I got it new on ebay for $300. For some reason I had to drill a hole in it to get the return throttle cable to hook up. Its got the place for it but no way to put the cable throw. Its really no big deal. Its got an notch were the hole should be. You probably could run with out it but I like the peace of mind that I can shut the throttle my self. And that kind has the air cut valve witch is nice on a street bike. It keeps the motor from running lean on deceleration. The thumper talk one don't have that. I had to get a different cable for the pull side cuz the stock one has a brass part thats curved and dont hook up well. And if it dont come with that one then you'll need the rubber piece that goes between the motor and the carb. Other then that jet it and your good to go. It defiantly has more throttle response and power but nothing crazy like you hear about on hear. I think a lot of people on hear have there stock carbs set up way wrong so when they switch to the fcr and jet it right its a big differences.
    2013 WR450SM
    Best youtube channel EVER!!!!!!!!!!!!!!

  8. #6
    Join Date
    Sep 2009
    Pisgah Forest, NC


    I've got a 42mm FCR with the power shot set up on mine with a high flow air filter & full yosh. between riding mine & one that was alomost stock ( only had the yosh system on it)

    there was a very big difference in the throttle response but yeah it's no KTM or Husky.
    07 DRZ 4hundo SM
    99 YZ125 Gotta love a 2 smoke!
    78 CB750F
    68 Electra Glide
    72 CB450


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