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  • XJ1100 pilot screw

    I pulled off my brass caps to check and clean the pilot screws and passages this weekend. When i counted the turns, they all fell between 2.5 to 3 turns except for #1, which was 1 1/8. Is this normal? I did nick the top of the screw with the drill bit when i was boring out the cap. The screw still functions fine (i didn't damage the slot for the screwdriver). But i find it hard to believe that the drill bit would have turned the screw that much if at all.

    By the way, just a few added tips that helped me: after nicking the #1 screw, I used a appropriately sized wrench socket on the others to stop the bit just short breaking through the cap. Then after much struggling with the wood screw and pliers, which didn't get me anywhere when trying to remove the caps, i used a 7mm socket and a drywall screw cut to an appropriate length. I inserted the screw through the socket and threaded it into the cap. A couple of turns with the screwdriver and it popped right out.

    So now i have the carbs put back together after cleaning a second time, and new float valves and gaskets. Presynced with the bread tie. If i have time this week i'm going to put the carb boots back (and use a little hi temp rtv with the gaskets), and then install the carbs. I'll try syncing with a homemade pressure balance device. But that pilot screw has me nervous. I'm going to read Ken Talbot's auditory technique in the tech tips, but i'll probably have questions.

    I'm missing the snorkle on my airbox. By the looks of the burn on the bottom of the seat, i think a previous owner destroyed it in a backfire. Is the absence of a snorkle going to hurt me (i mean performance-wise, not burning-ass-wise) as long as nothing is blocking the hole where it's supposed to be?

    Mike

  • #2
    The snorkle is supposed to make a difference. Just like velocity stacks are supposed to make a difference. But hey, on one of mine, I have K&N pods with no airboox at all and I sure like them!
    Skids (Sid Hansen)

    Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.

    Comment


    • #3
      Hey Mike,

      Well, I'm sure I recommended a metal screw? As for the intake boots and gaskets, it's recommended to NOT use RTV, but some other non-hardening sealant that is not silicone based. Silicone and gas don't mix well! Either some Yamabond, or Permatex would be preferred. As for the pilot screw, it possibly could have gotten turned by the drill bit, but once you clean them, synch them, etc., it doesn't matter, cause you're going to reset them to your liking. They were usually set lean for emissions! BTW, you were counting the turns as 2 flips of the blade for one turn, otherwise you might have been counting 1/2 turns, 180 degrees rotation of the blade?? OF course with the XJ, they may have set them a bit different due to the YICS vs. the XS's!?

      I thought the snorkel was more for getting cooler air from farther away from the engine and to prevent water entering during rain!?

      Many folks have drilled the bottom of their stock box anyways, so it shouldn't be a problem!
      T.C.
      T. C. Gresham
      81SH "Godzilla" . . .1179cc super-rat.
      79SF "The Teacher" . . .basket case!
      History shows again and again,
      How nature points out the folly of men!

      Comment


      • #4
        Originally posted by TopCatGr58
        Hey Mike,
        Well, I'm sure I recommended a metal screw?
        Actually, TC, you did recommend a metal screw. I, a bit earlier, had recommended a wood screw as that was the first thing that came to mind. In hindsight, a metal screw would have a slightly finer thread and probably have done a better job of removing the cap than a big 'ole coarse thread wood screw.
        Ken Talbot

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        • #5
          Yeah, a finer thread would've been easier, but the 7mm socket helped quite a bit.

          I was counting one turn as 360 degrees. The number of turns (from 1 to 4, respectively) were 1 1/8, 3, 2.5, 2 7/8.

          I've used RTV on a float bowl for a KZ400 before and didn't have a problem. And i got the high temp rtv idea from a guy at work that used it on his '82 Seca 750 intake boots. I can't imagine there'd be enough liquid gas in the intake boots to be a problem, but if i'm going to do it, i might as well do it right. I'll have to check into the permatex tomorrow. I might be able to get some from work.

          From what i've been reading on forums here, the pilot screw is normally set rich? It's better to have rich blackened plugs than lean, hot, melted ones? And just so i'm sure on this, the higher the pilot screw setting (more turns) the richer the mixture?

          BTW, thanks TopCat and Ken. I appreciate all the help and tips i've been getting from you. I'm having a lot of fun on this project and probably would've f'd it all up had I not found this website.

          Mike

          Comment


          • #6
            Hey Mike,

            The plugs won't be BLACK and SOOTY, but may have a slight black ring around the base of the plug, the part that the electrode is a part of. The MAIN JET will mostly control how lean or rich they are since that'll be where you'll be doing most of the running of the engine, not just idling....but that's why they recommend taking readings on the plugs ON THE ROAD doing a throttle chop technique, otherwise you end up reading the pilot jet!

            Also, you'll need to check out the tips regarding the YICS tool, because the XJ's head shares the flow across all four cylinders, and so to do a proper vacuum synching as well as the pilot jet tuning, you need to block off that sharing tunnel....temporarily.

            I've used the High Temp "COPPER" Gasket replacement type of RTV sealant on my SOFA plates for the high pressure oil chamber, and have not had any problems either! It's just the silicone stuff has a way of squeezing out from inbetween the parts being put together, and could get into the intake/engine!?

            Glad you're having fun, and that we've been able to help, but the real fun will be when you can put this thing on the road and grab a handful of throttle.....hang on!!!
            T.C.
            T. C. Gresham
            81SH "Godzilla" . . .1179cc super-rat.
            79SF "The Teacher" . . .basket case!
            History shows again and again,
            How nature points out the folly of men!

            Comment


            • #7
              Oh yeah... I can't wait for that day. I'll need to floss all the bugs out of my teeth afterwards 'cause i'll be grinning the whole time

              I've already got the YICS tool made, but i'm going to recut some new rubber pieces to do the plugging. My first whack at it i didn't get the ends too square, so the washers tilt a little when i crank it down tight.

              Also, i don't think think the tool is long enough, either. I made it to the dimensions shown in the tech tips but the end of it seems to fall on the #2 side of the #3 port to the YICS passage. I'll try attaching a pic later, so you can see what i mean.

              What does SOFA stand for?

              Comment


              • #8
                Originally posted by wiggumpi
                What does SOFA stand for?
                Read THIS TECH TIP to find out!
                T.C.
                T. C. Gresham
                81SH "Godzilla" . . .1179cc super-rat.
                79SF "The Teacher" . . .basket case!
                History shows again and again,
                How nature points out the folly of men!

                Comment

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