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About Tenshikurai

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  1. Tenshikurai

    YZ426 won't idle without choke

    Just got some parts in, the washer on the fuel screw didn't make a difference, but replacing the seal on the slide cover made a world of difference. Got it all back together and it idles now, still seems a little off though, but I'll play with jetting some. Chased down a few small fuel leaks and ended up replacing all the o-rings and gaskets by the time I was done. Seems like I'm seeing a huge difference between idle RPM with the choke on/off. It idles really high with the choke on, is this normal? This is my first 4-stroke thumper so I've got a bit of a learning curve ahead of me. Oh, current setup is a 165 main jet, and 42 pilot jet, fuel screw is 1.5 turns out. I didn't seem to notice much of a difference between a 42 and a 45 pilot jet, but the 48 was definitely rich.
  2. Tenshikurai

    YZ426 won't idle without choke

    I found one possible source of an internal vacuum leak, the seal between the slide plate and the slide is broken/mostly missing. Basically 1/4 of the rubber seal is there, the rest is gone and probably got ate by the motor. Sounds like I'll need more parts.....
  3. Tenshikurai

    YZ426 won't idle without choke

    I've just pulled the carb back off again and checked out everything again. I pulled the fuel screw all the way out and discovered the washer is missing from the end. The O-ring is still there and intact, would this be enough to cause the problem? I've got an R&D fuel screw coming, as well as a full rebuild kit. Hopefully that'll be enough to cure the problem.
  4. I just recently picked up a 2000 YZ426 from a friend of mine, and have been having some idle issues with the bike. Basicly it won't run with out the choke on. The bike runs fine with the choke on, starts easily, but runs really lean and dies the moment you push the choke in. The bike hasn't been run in 6-7years, so I presumed the carb might have been varnished up, pulled it apart to find that it was pretty clean, but cleaned all the jets and passages I could. I verified the pilot circuit was clear, and re-assembled it. The fuel screw was at 3-1/2 turns out when I dissassembled it, I left it there fired it back up and had the same problem. The pilot jet was already upsized to a 45, I replaced it with a 48 and it still runs lean at 2-1/2 turns out. I've checked for vacuum leaks, verified the valve adjustment is within spec, and am still stumped as to the problem. Mods on the bike are no air box lid, aftermarket foam air filter, DSP titanium full exhaust, E-line stator, and the blue wire mod. Currently the carb has a #48 pilot jet, #162 main, #72 starter jet. Air temp is 50-60 degrees, altitude is 0-100 feet, humidity is 40-50%. Any suggestions on things to check?