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04 Kat Heart Transplant and some issues to follow!

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  • 04 Kat Heart Transplant and some issues to follow!

    Morning Folks!
    I snagged a decent 2004 Kat about a month ago with a few “issues” biggest being that cool new mod done by someone who had no clue that these motors take oil to run and left me with a crankcase window to properly view the number 4 piston and connecting rod

    A good friend of mine and my RC for the MC I run has a Bandit and donated the motor out of it for the Kat. Swapped the new heart into the Kat and had to adapt a few things (the intake boots for the bandit do not accommodate the Kat carbs) and of course the EGR system off the. Bandit motor as well.

    Of course the motor fit just fine and everything bolted up as it should. Had the two motors completely out and swapped in under 3 hours which was pretty awesome considering the last motor swap we did was on one of my old Goldwings and it took a better part of a day to get it done.

    Cleaned and Rebuilt the carbs, Set the air/fuel mix screws to 2.5 turns out and slapped them back in. After a bit of a protest she fired right over but won’t stay running...So the carbs are coming off again this evening and I’ll go back through them to make sure everything is seated properly and all that other good stuff.

    NOW - question time!

    First, My local bike mechanic advised to set the air/fuel screws to 3-3.5 turns out (we are in Georgia) and advised these bikes came from the factory set super lean because of the emissions nonsense. I’ll give that a shot and see how it works. BUT, the petcock has that vacuum line off the back of it which in my opinion needs to be hooked into the carbs for the bike to continually run....does that sound right?

    I’m still waiting on the service manual for this machine to come in so I’ve got it...checked the forum for a downloadable copy but the two that were posted the links don’t work in for me so I’m shooting mostly from the hip on this one.

    Basically - My primary concern is the air fuel mix and the screw settings. I neglected to mention the bike has a D&D on it now and I’m

    Not sure of the jet size but I’d bet they’re probably still stock so they need to be changed.

    Regardless - sorry for the long ass post, just need the bike to fire over and run so my other half can get out on her own two wheels and explore this state (she’s from NZ)

  • #2
    Ok. Below I have posted the links to 2 sticky threads in here that I think would be very helpful to you. LOTS of good information about Kat engines and carbs in there. The answer to the other question you had, Yes. The port on the back of the fuel petcock needs to be hooked up to the carbs. It uses engine vacuum to open the valve to allow fuel to flow from the tank down to the carbs. You can put the valve on Prime to bypass that function, but you should really only use that to initially fill the carbs after cleaning or to troubleshoot your bike. Also, if you don't have the petcock hooked up to the carburetors, then you may have an open vacuum port on the carb sucking in too much air preventing it from running very well.



    Freedom is the sure possession of those alone
    who have the courage to defend it.

    First Sergeant(Ret) - US Army - 21 years


    • #3
      best write up for carb tuning I refer to it often anything of 3 on the pilot is high but the whole thing takes patience and commitment I'd start around 2 turns out and work from there at 1/4 turn at a time and log the results.. just my 2 cents
      Last edited by Lachie; 08-11-2020, 10:52 PM.
      “Anything that happens, happens. Anything that, in happening, causes something else to happen, causes something else to happen.
      Anything that, in happening, causes itself to happen again, happens again. It doesn’t necessarily do it in chronological order, though.”
      ― Douglas Adams


      • #4
        Thanks for the info up there -

        I ended up taking the carbs apart again last night just to make sure everything was lined up right and double checking for any potential trash in the carbs. I found one of my air/fuel screws to be broken (no nipple on it) and took note of the jet sizes in the event they need to be replaced with a larger jet because of the D&D pipe. The stock pilots are a 12.5 and the mains are a 117.5.

        SO! Im looking for a new air/fuel needle today And I think I’m going to bump the pilots up to a 15 if I can find the right one. Been looking at a few jet kits or jumping it to a stage 1 kit rather which seems to be a good idea as well.

        In the meantime- it’s a waiting game as always