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Carburetor replacement

Discussion in 'Tips and Tricks' started by Sheperdale, May 31, 2009.

  1. mini me

    mini me New Member

    Just wondering if you guys are talking about the same pump ( accelerator pump that are on the carbs themselves ) and the fuel pump sheperdale is talking about. I need and want to do this so bad i hate the stock carb and need to be able to jet the carb because of the air box mod and exhaust mod I have done to my truck

    thanks for the wicked post
  2. goldstar

    goldstar Member

    Accelerator pump

    Yeah Mini Me.
    The accelerator pump is what we were referring to. What mods did you make to your air box and exhaust?
  3. mini me

    mini me New Member

    For the air box I removed the lid and put a K N filter in it. Punched out the catalytic converter and replaced muffler with a universal glasspack muffler.

    Should i be looking for a carb with a accelerator pump to try?
    I have one on my Honda trx 450r quad maybe that would work? I forget the specs on it but I will check and see what I got I know on my quad when I removed the air box lid it would die hard if u hit the throttle fast, to fix it i had to change my leak jet to smaller size to make accelerator pump out more fuel
  4. sdjenk

    sdjenk New Member

    So how is the truck running now with the new carb? I am looking to do the same thing. Could you tell me what motor size you have CC? and which carb is it you used and jet sizes would be helpful. Thanks
  5. Sheperdale

    Sheperdale Member

    Still running

    Well the truck with card is still running by what the wife tells me, I have been deployed for a year. It is a 660 and the carb is a mikuni tm 32 flat slide. It's been running great ever since I did it. I found a three position choke cable of a ski doo and ran it into the cab. It's been working great.
  6. Casper

    Casper New Member

    I was wondering how the TM32 did over-all, would you do it again? The carb on my Suzuki Carry is crapping out, I thought about changing to an aircraft carb. However the TM32 is at a decent price and it does look like it fit in just right, as I was going to install a snorkel as well.
  7. Casper

    Casper New Member

    Another question, what would be wrong with using a Mikuni 32mm VM round slide carb instead? It is quite a bit cheaper yet, is it because of top end acceleration "difference between round and flat slide"?
  8. Casper

    Casper New Member

    I just got my Mikuni TM32 and the Mounting flange today. WOW, after removing the old factory stock carb, this is really going to clean things up and make it easier to do maintenance. I started installing the new carb, however I elected to used the spacer off of the old carb to set out the new carb an extra "approx. 1/2" ". This way it will make it just a little easier to work on. I got the fuel line hooked up, the snorkel started, put a good clean cloth "lent free medical towel" over the intake, just to test fire. Started right up, almost idle perfect without adjustment, I think I may have a vacuum line issue "hmm".
    One thing that is an issue for me is the throttle cable. I'm going to have one made "as you just can seem to find a cable in that length with the elbow on it". The top of the carb sets pretty close to the bottom of the cab, I wished the carb was an 1" shorter. Anyway I will post some pictures when I get it finally done like I want it.
  9. Sheperdale

    Sheperdale Member

    Sorry about not getting back to you but sounds like you are really on your way. The cable thing got me into manufacturing my own. I did buy a 90 degree tube that screwed into the top of the carb so I didn't have bent housing. It just fit under the beam between the seats. It was actually for a kehin carb but screwed right in. I run mine a little leaner all the time but not so much it runs to hot or backfires.
  10. Casper

    Casper New Member

    Good to hear from you Sheperdale, carb is still a work in progress, one thing that I had to do was change out the 3.3 needle valve "I could figure out why it would puke out some gas from the drain tubes, then it came to me". The TM32 Mikuni is a bike carb first and foremost, hence it was made for gravity feed, I installed a 1.5 needle valve for a fuel pump application and stopped the purging of fuel.
    I am currently working with a company out of California to make a throttle cable that will work perfect for the job at hand, when we get it done right I will post it. I told them there will be others that will want to do this "if it all works good".
    I got my little rig running but I found other problems "not carb", bad cap and rotor!
    Oh, I also installed an aftermarket fuel pump, mine was junk. The new one came with an inline fuel filter that screwed right on the inlet side of the pump. This really cleaned up the frame rail back by the gas tank.

    I will try and get some pic's on here when I get some time "really busy now with work".
  11. Casper

    Casper New Member

    Sorry for the delay on the Mikuni TM32 carb change over. Here is where I am at, now that I changed the needle valve jet to a 1.5 I was still experiencing the engine burning rich. So I order a couple of smaller pilot jets, as well as 4 smaller main jets. I now have the #40 pilot jet in, I have it tuned to 1 and 3/4's turns out on the air mixture screw and it idles perfect. FYI for you do it yourselfers, I use a piece of white "old" TEE shirt to perform a quicker check of how rich the engine is burning, it is not perfect but it gets you close. Take the white cloth and stretch it over the exhaust pipe and time it for 15 seconds, so every time you adjust your mixture screw and the such make comparisons. It should be very very light on the cloth, then when you think you have everything close drive it for awhile. Then pull a plug and check the plug for the burn.
    Now onto the Main jet, it comes from the factory with a #250 main jet, I am currently down to a #220, I may go down one more to the #210. I will see how the plugs look after a few days, but I still don't have the top end power yet. Also I have the needle currently clipped in the #2 position, I may move this as well to the #1 position for a little more air flow.
    Oh, one more thing. If your planning on doing this conversion be aware that this carb takes very little fuel pressure, I am learning this the hard way, now I am down to a 1.5 to 2.5 psi Facet pump. I had a 4.5 to 7.5 Facet on there before and it was way too much pressure.
  12. james23

    james23 New Member

    For replacing carburetor, clean the area where you will mount the new carburetor. Scrape off all dirt and gasket material and, using a strong solvent, clean the area. You don't want the carburetor sucking air because of an imperfect seal. Place the new gasket in place. The gasket should have a light coating of gasket sealer on each side.

    metal identification tags
    Last edited: Nov 10, 2012
  13. Sheperdale

    Sheperdale Member

    Its benn a while since I've been on and was checking to see any progress with any other carb swaps. I moved back from western Alaska to civilization and now have a garage to work in. Wonder casper if you ever got cables made and where after having numerous of my own cables failing. Hope its still running good.
  14. Borg

    Borg Member

    I have a Mikuni BSR 36mm that may need to find a new home in the future... if anyone wants to buy it though, shoot me a PM.
  15. Sodbuster

    Sodbuster New Member

    I see this is a old thread but this is what I'm trying to do If anybody can answer my question please jump in.
    I am in need of the carburetor mounting flange that goes In-between the carb and the manifold. On my 3G83 Mitsu manifold I have a measurement of 80mm mounting holes from center to center than I need on the other side to be 40mm to affix a Kien carb. I want to do what Shepard did on his but I can't find a manifold that has such a large hole spacing 80mm center to center.
    Thanks, Greg
  16. KCCats

    KCCats Member

    This sounds good, but have you considered the Weber 2 stage carb? I had one on a Datsun may years ago, too big?
  17. KCCats

    KCCats Member

    My suggestion, being a Snowmobile Mechanic, is this.
    Take a plate of allum, thickness to be determined?
    Make it taller than needed, but wide enough to make the seal?
    Then drill all the way threw the thin edge!
    So lets just say a plate about 4" wide, 6" tall and 1/2" thick?
    Drill the hole threw the bottom edge and tap it for 1/4" Iron pipe thread!
    Then just put 1/4" IP X hose barb fittings on it!
    Run your coolant threw the allum plate!
    Next drill your 80mm spaceing!
    Then at like a 45, drill the othere bolt patteren (it will be called a HD pateren)
    Tap and install studs to hold the rubber mounting flange.
    Then in the very center just drill a 2" (?) hole for the center bore with a hole saw drill!
    Now if you need another vac port, just drill into the side edge and tap 1/8" pipe tap and get a hose barb fitting!

    Now my question is why a 32mm?If you still lack top end, Why not a 40 or 44mm?
    What has your fuel milllage done?
  18. KCCats

    KCCats Member

    Again Im a snowmobile wrench!
    What if??
    I could make 3 individual intakes and triple carbs?
    Martin Fornage likes this.
  19. melly

    melly New Member


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