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Odd Carb Issues

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  • #1

    Odd Carb Issues

    I'm working on a 96 Katana 600. It has a larger/complex float system compared to any other bikes I've worked on. Also there seems to be a rubber plug that actually closed off/plugs up the idle jet...this seems pretty usual to me...I've never seen a plug in the idle jet. Anyways after cleaning and blowing out everything...and a new choke cable...I'm getting the bike to run good with the throttle at 1/4 to full but it just wont idle. Any ideas of where I may need to look next?

    All the settings are factory...are there some air passages that could be clogged??? Any help would be great...this one has me a little confused.
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  • #2
    Originally posted by bolesa56 View Post
    I'm working on a 96 Katana 600. It has a larger/complex float system compared to any other bikes I've worked on. Also there seems to be a rubber plug that actually closed off/plugs up the idle jet...this seems pretty usual to me...I've never seen a plug in the idle jet. Anyways after cleaning and blowing out everything...and a new choke cable...I'm getting the bike to run good with the throttle at 1/4 to full but it just wont idle. Any ideas of where I may need to look next?

    All the settings are factory...are there some air passages that could be clogged??? Any help would be great...this one has me a little confused.

    Idle system is not fully clean. If your not removing all the jets and soaking the carb bodies, there are some internal spots that are not getting cleaned enough to allow fuel to flow for the idle circuit.

    A/F screws, pilot jets removed, etc...

    The plugs are to seal off so that the only source of fuel for the pilot jets are from small holes inside where the plugs go... the fuel actually enters from that small hole from the main jets/emulsion tube area.

    Krey
    93 750 Kat



    Modified Swingarm, 5.5 GSXR Rear with 180/55 and 520 Chain, 750 to 600 Tail conversion, more to come. Long Term Project build thread http://katriders.com/vb/showthread.php?t=96736

    "I've done this a thousand times before. What could possibly go wron.... Ooops!"

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    • #3
      Ok thanks...I've never seen a set up like that before. I've had quite a few carbs apart, a few of them cv type but I've never seen the idle jets pluged like that...seems like too much trouble when the old way works just fine. I'll pull them and go through them again and give you an update.

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      • #4
        Just some additional info while working on the carbs...

        The black plugs you mentioned seals off the access port to the pilot jets, and are so that they are easily removed but the fuel flow comes from elsewhere. The fuel flow comes from through the main jet into the emulsion area... where a small hole then flows fuel into the pilot jet area. If that hole is not clean (part of the carb body) then even with clean pilot jets, you will still not flow enough fuel.

        This is one of the reasons why I recomend on a cleaning to remove all parts and use an actual carb dip to soak the bodies in along with the loose parts like jets, etc.... It's also part of the reason a "quickie" cleaning with just carb cleaner doesn't do a good enough job.

        Info on why/how a CV carb works... The only issue I have with this diagram is it does not show the passage between the Main Emulsion area to the Pilot jet tube. Alot of the other carbs do not have that (Pre Kats seem to be special in that... )



        Why the "needle jets" are also called "emulsion tubes"....



        Krey
        93 750 Kat



        Modified Swingarm, 5.5 GSXR Rear with 180/55 and 520 Chain, 750 to 600 Tail conversion, more to come. Long Term Project build thread http://katriders.com/vb/showthread.php?t=96736

        "I've done this a thousand times before. What could possibly go wron.... Ooops!"

        Comment

        • #5
          Great info...I've had a pretty good understanding of vacuum slide (CV) carbs. I love the old manual slide carbs...but the day of EPA and Emissions have pretty much put an end to those things. I've got the main and idle jets soaking right now...I also blew air through the idle jet channel and now I can feel air pushing out of the main jet channel as well as the air jet on the air box side of the carb. I'm confident the tiny connecting channel is clear on each carb now. Those things are really tiny!

          I went ahead and pulled the air plugs and blew them out and reinstalled them at 1.75 turns out. I'll button it back up this weekend and see if that handles things. I'll keep you updated. Thanks again.

          Comment

          • #6
            Originally posted by bolesa56 View Post
            Great info...I've had a pretty good understanding of vacuum slide (CV) carbs. I love the old manual slide carbs...but the day of EPA and Emissions have pretty much put an end to those things. I've got the main and idle jets soaking right now...I also blew air through the idle jet channel and now I can feel air pushing out of the main jet channel as well as the air jet on the air box side of the carb. I'm confident the tiny connecting channel is clear on each carb now. Those things are really tiny!

            I went ahead and pulled the air plugs and blew them out and reinstalled them at 1.75 turns out. I'll button it back up this weekend and see if that handles things. I'll keep you updated. Thanks again.
            You will probably find 1.75 (yes, that was OEM specs in the day) is a little lean now days with the new fuel mixtures. I would recomend 2.5 turns to start and fine tune from there. That's been a pretty universal good start for these carbs today.

            Krey
            93 750 Kat



            Modified Swingarm, 5.5 GSXR Rear with 180/55 and 520 Chain, 750 to 600 Tail conversion, more to come. Long Term Project build thread http://katriders.com/vb/showthread.php?t=96736

            "I've done this a thousand times before. What could possibly go wron.... Ooops!"

            Comment

            • #7
              Sorry I wasn't able to get back online sooner...my computer has been sick the last couple days. Anyways, I was able to really go through the idle and choke circuits really well, paying close attention to the areas you mentioned. I buttoned everything back up and cussed with the air box boots until they all finally decided to fit properly on the carbs. After priming for about 10 seconds the bike fired up and idled...not perfectly but after a little fiddeling I was able to get it to an acceptable 1500 rpm. I checked my bolts and took a little test ride...the bike pulled evenly from idle through red line with no noticable flat spots and seemed to hold cruising speeds with no surging. These machines have pretty good power for an air cooled 600...not quite the topend rush of a liquid cooled 600 but the torque seems nearly even. There's definitely more power than the old seca 600 from around the same period. Anyways...thanks again for the help...I'm sure you saved my alot of time. I wanted to make sure and update the post because I can't stand it when someone doesn't follow through!

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              • #8
                Glad to hear you got it worked out...

                Krey
                93 750 Kat



                Modified Swingarm, 5.5 GSXR Rear with 180/55 and 520 Chain, 750 to 600 Tail conversion, more to come. Long Term Project build thread http://katriders.com/vb/showthread.php?t=96736

                "I've done this a thousand times before. What could possibly go wron.... Ooops!"

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                • #9
                  You can leave the airbox & carbs together when you remove them, just tip the whole thing up and out. Reduces cussing about boots.

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                  • #10
                    Wish I wouldve known that...I needed to clean the air jets on the intake side so I wouldve still needed to take them off...but putting them back on while on the bench wouldve have been MUCH easier...thanks guys. The bike's owner came and picked it up tonight and it's running great. The front wheel bearing feels a little chewy so I told him to order a set and I'd slap those of for him...other than that its a pretty solid bike for $1400.

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                    • #11
                      I wish i would have had those pics before i attacked my carb project...
                      -Noe-
                      2000 Katana 750

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