Home Forums Shifter Karts Honda CR125 intake manifold and the Mikuni carb

This topic contains 15 replies, has 7 voices, and was last updated by  andy graham 5 years, 9 months ago.

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  • #4434

    Robert Horvath
    Participant

    UPDATE :

    FYI Shifter Go Kart Guys,

    For the open/modified
    class of Honda CR125 Shifters.

    The very short fuel path direct fit Honda CR125 Shifter intake manifold for 38mm 2 flange bolt types of carburetors is all done .

    It has a 11 degree right rotation angle
    to to clear the kick start bump ( Carbs like the externally adjustable Mikuni 38mm Carbs work really well )

    No more rubber boots with right angle turns to disturb the fuel flow !

    And even a more perfect fit when used in conjunction with the V-Force 3 Reed Cage box .

    I’m getting this experimental test carb fitted up to the CR125 Honda.

    Mikuni Super Butterfly Type SBN38mm Diaphragm Pump Carburetor
    No jets to change ever (well almost never) as it has easy to get to externally adjustable low & high speed mixture screws just like the Vortex RoK-tt carb only a much bigger bore (38mm) to fit the CR125 Honda engine and the fuel pump is built right in too.

    I’m getting tired of always taking off the carb to change the high & low speed pilot jets and I don’t care for float types of carbs either.

    These are one of the best performing and easy tuning carburators that money can buy.

    see below:

    Thank You

    Bob

    Robert Horvath

    W352N6446 Road J
    Oconomowoc Wi 53066 U.S.A.

    rhorvath4@wi.rr.com

  • #4435

    Robert Horvath
    Participant

    Honda Cr125 intake manifold

    intake and carb

    Intake and carb together

  • #4491

    James Bell
    Participant

    Hey Bob,
    Hope your daughter is doing better. Anyway I’m still interested in this carb set up. Are you finished with testing, fabing? PM me a price shipped.

  • #4537

    Frank Rapisarda
    Participant

    Hey Bob nice work, what is that carb off of ?

  • #4553

    Chris Reinhardt
    Participant

    It look like a aftermarket only carb, no OEM application….

    http://www.ebay.com/itm/Mikuni-Super-SBN-38-mm-38mm-Carburetor-Carb-Brand-New-/190459013132

    CR

    Chris Reinhardt

    CR2 Motorsports

    http://www.cr2motorsports.webs.com/

    XV Racing Products

    http://www.xvengineering.com/

    ­­

  • #4904

    Robert Horvath
    Participant

    On the Mikuni carb setup:

    I posted this to see if there was much interest in this project and I see that there is…..So I’ll work up a price for the setup.

    Would you karters get your own carbs off ebay like this one ? :
    http://www.ebay.com/itm/Mikuni-Super-SBN-38-mm-38mm-Carburetor-Carb-Brand-New-/190459013132

    Or would you like the Mikuni carb, air box inlet adapter, primer system, gasket, nuts & bolts, throttle cable bracket , custom intake manifold and V force 3 reed box as a complete system ?

    Probably not cheap when all added up ?

    The intake manifold is about 1/2 inch thick someone asked.

    The Carb is a generic replacement carb for my 1995 Polaris triple carb 750 cc watercraft (JetSki). see photo down below :
    3 carb JetSki setup

    3 carb JetSki setup

    Each carb feeds each 250 cc cylinder.

    The Jetski has such tremendous throttle response I thought I give it a try on my Honda shifter….It works well so far and I’ll keep you posted after much more track testing of the setup.

    I do see now after track testing that I have to set the popoff pressure much lower.

    Ocono Bob

    Thank You
    Robert Horvath

    W352N6446 Road J
    Oconomowoc Wi 53066 U.S.A.

    rhorvath4@wi.rr.com

  • #4994

    James Bell
    Participant

    All im interested in is Mikuni carb, air box inlet adapter, primer system, gasket, nuts & bolts, throttle cable bracket , custom intake manifold. I can get the vforce reed cage myself. But for now this kit would work with a stock honda reeds and cage no?

  • #5383

    Broque Ward
    Participant

    looks interesting. that sure will be a nice setup, the keihs are great but the jet changes suck.

     

    does this carb have a fuel pump on it as well? looks like it but im not sure.

     

     

  • #5425

    Robert Horvath
    Participant

    You asked “does this carb have a fuel pump on it as well? looks like it but im not sure”

    The answer is > yes it does!

  • #5527

    Alan Sheidler
    Participant

    Do some sanctioning org’s prohibit carbs that have an integral fuel pump?

  • #6954

    Robert Horvath
    Participant

    Update > on the onboard
    Carburetor Adjusting Tool

    FYI

    I’m going see if I can modify for permanent installation a couple of these carb adjustment tools pictured down below to bring the Mikuni carb mixture low & high speed adjustment screws up to the front of the Honda CR125 cylinder head so maybe the driver could adjust the Carb on the fly instead of coming into the pits for a adjustment.
    Carburetor Adjusting Tool
    The carburetor adjusting tool has a flexible cable to easily access often hard to reach carb adjustment screws.
    Carb Screw Adjusting Tool Part Number 53-999 $24.95 each.

    Here is a photo of two of them attached to the new Mikuni jet ski carb on the Honda Shifter.
    Carburetor Adjusting Tool

    Blue for the low speed mixture adjustment… and …Red for the high speed mixture adjustment.

    Ocono Bob

    rhorvath4@wi.rr.com

    Robert Horvath

    W352N6446 Road J
    Oconomowoc Wi 53066 U.S.A

  • #6955

    Robert Horvath
    Participant

    Alan Sheidler said :

    Do some sanctioning org’s prohibit carbs that have an integral fuel pump?

    The tracks around here in WI. USA don’t care when going though “TEC”

    Ocono Bob

  • #9319

    Robert Horvath
    Participant

    Results now are in

    On using the :

    Custom Honda CR125 intake manifold and the Mikuni carb setup

    Hi back shifter guys.

    It’s been about six weeks now that we have been using the new setup

    I didn’t want to say anything before until the unit was thoroughly Race track tested.

    The answer is easy ..JUST ONE WORD > Awesome Performance!

    We have taken a full second off our own personal best time at our local track ( Badger Raceway Dousman wi.) and after hundreds & hundreds of laps with absolutely no Carb trouble at all.

    A good lap time at Badger is anything under 38 seconds….We are consistently in the 37.20s with the Honda CR125/Mikuni now,

    I’m not setup to “Retail a kit ” to the general public.

    But I’m making arraignments now to sell it through a few of the better shifter kart shops and on line from them also.

    It will be priced about on par with the Swedetech Honda intakes.

    The complete intake kit would consist of the intake, all gaskets all, hardware,throttle cable, bar type throttle cable bracket, 38mm air filter/box adapter and to inc.this disclaimer below :

    “As when installing any performance product, a degree of mechanical ability is required. If after reviewing the parts you don’t feel that you can properly complete this installation, take your kart to a competent professional. Proper installation and adjustment will save time, money and aggravation.”

    Because of all the tight quarters I recommend installing the carb & and intake as one piece with a very long ball type allen wrench.

    Then it’s easy to do.

    I got so tired of always having to take the stupid Honda CR125 Keihin carburetor
    off to change jets I’m taking a lot of them off the shifter Karts in our little classic shifter club and tossing them out or selling them….I think they are all JUNK.. pump arounds too….But maybe that’s just me ?

    Here below is a long story of what I’m doing for carbs instead …AND I’LL TELL YOU THIS SETUP REALLY WORKS WELL ON THE CR125s.

    This below looks very clean and it solves all the fuel system issues.

    Robert Horvath

    Participant
    UPDATE :

    FYI Shifter Go Kart Guys,

    For the open/modified
    class of Honda CR125 Shifters.

    The very short fuel path direct fit Honda CR125 Shifter intake manifold for 38mm 2 flange bolt types of carburetors is all done .

    It has a 11 degree right rotation angle
    to clear the kick start bump ( Carbs like the externally adjustable Mikuni 38mm Carbs work really well )

    No more rubber boots with right angle turns to disturb the fuel flow !

    And even a more perfect fit when used in conjunction with the V-Force 3 Reed Cage box .

    I’m getting this experimental test carb fitted up to the CR125 Honda.

    Mikuni Super Butterfly Type SBN38mm Diaphragm Pump Carburetor
    No jets to change ever (well almost never) as it has easy to get to externally adjustable low & high speed mixture screws just like the Vortex RoK-tt carb only a much bigger bore (38mm) to fit the CR125 Honda engine and the fuel pump is built right in too.

    I’m getting tired of always taking off the carb to change the high & low speed pilot jets and I don’t care for float types of carbs either.

    These are one of the best performing and easy tuning carburators that money can buy.

    see all photos below:

    Intake

    Carb & Intake

    Carb & Intake assembled

    Intake on the Honda

    Tilly

    Or a big bore Tilly is a good fit on the Honda too for short tracks!
    Note > a primer bulb also for easy starts :

    Important note below :

    Road America is a famous road course located near Elkhart Lake, Wisconsin

    Here are the results of the first time out at Road America with the new intake set up.

    I installed the kit on team Craig Hemmen / Bob Horvath (That’s me)

    We ( Craig Hemmen age 61 the driver of Kart # 92 & me Bob Horvath the mechanic age 68) were competing all day at Road America) and of all the Pro shifter Karts (about 22) there today…We got fast time of the day and that gave us the Pole Position for the feature race and a First place Win in for our Honda class too.

    The ICC shifters and the Honda’s all run together in one class due to the small number of each

    Date 24-08-2013 13:36
    Length 0.8000 Miles
    Best lap time 44.463 In lap 4
    Best speed 64.773 By competitor Craig
    Hemmen/Bob Horvath
    pos start no. competitor laps total time diff best time best lap best speed
    1 Honda engine 92 Craig Hemmen 6 04:36.982 44.463 4 64.773
    2 ICC type engine 65 Darrick Lang 6 04:54.457 17.475 44.690 5 64.444
    3 ICC type engine 17 Dayton Bender 6 04:56.302 19.320 44.829 2 64.244

    The Intake on the Honda

    The Intake on the Honda

    Thank You

    Bob

    Robert Horvath

    W352N6446 Road J
    Oconomowoc Wi 53066 U.S.A.

    rhorvath4@wi.rr.com

    Honda;Mikuni;Intake;Manifold;Shifter;Carb

  • #9389

    andy graham
    Participant

    those SBN38’s were stock on the Sea Doo 785 engine back in the 90’s…there were a couple of companies that were known for modding those carbs to get some serious results…I remember Buckshot was kinda like the Swedetech of jetski racing when it came to carbs, and there was a company in FL called Red Top that changed the fuel distribution from a nozzle/sprayer to an angular distribution…I ran both set ups, I had better luck with the buckshots than the red tops, and I think they started as 38s and then had a bigger venturi pressed in as the mod….I bet if you search ebay for “sea doo xp carb” you’ll find plenty…there was also a place in Miami called PPG (Perry Performance Group) that did their own mod on the stock carbs on the 785s with good results….just food for thought

  • #9450

    Robert Horvath
    Participant

    Andy,

    Thanks for the heads up.

    I’ll look into both those carbs you mentioned and I’ll give Perry a call too.

    Ocono Bob

  • #9465

    andy graham
    Participant

    in stock form on the sea doo they were black bodied carbs, the buckshots and the red tops were silver bodied like in your pic…I was thinking more about this yesterday — we never used the carb mounted fuel pump, they make (made) a block off plate to remove the pump and allowed you to run the big mikuni external pump…and I forgot all about the guys who were considered “The Best” when it came to pwc carbs — Novi.  Buckshot got fancy and made manifolds, big (50mm) billet bodied carbs, linkage etc….Novi stuck to carbs and man were they awesome.  Easy to tune.  Pretty sure Buckshot is gone or has moved on…last I heard he was building dune buggies in SOCAL, but even that was a long time ago…the guy in FL making red tops has been gone for a long time also, I think the name of his company was True Cad Designs…they’re out there somewhere, hope this is at least a little helpful….good luck.

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