Help with 1999 2 stroke problem

Discussion in '2 smokers' started by rjmorel, Mar 23, 2019.

  1. rjmorel

    rjmorel Dual Sporticus

    Joined:
    Oct 31, 2005
    Oddometer:
    534
    Location:
    Walla Walla, WA
    Restoring a 99 Suzuki DS80 for a 6 yo girls birthday.
    Problem is when I start it , it revs way up for a few seconds , then dies unless I give it some choke and it warms up . I can ride it after warmed up ,controlling the rpms with the kill switch and choke to keep it running at first , then it seems to settle down and run better. Very hard to get it to idle and keep running. The slide is returning to the idle position when I let go of the throttle.
    Is this characteristic of an air leak?
    I've replaced the ignition side crank seal thinking it was leaking, Ultrasonically cleaned the carb and bought and installed a carb kit for it.
    The throttle slide cap that's on the carb where the throttle cable goes in has a black rubber gasket that is deformed out of round and you can see the line impression the top of the carb makes on the gasket and it may be missing the gasket in 2 places judging from the line in the gasket.
    Could this cause an air leak coming from this cap?
    Thanks, her BD is coming up in 2 weeks and I'm really wanting to get this figured out. rj
    #1
  2. snarlyjohn

    snarlyjohn Human money repellant

    Joined:
    Apr 1, 2016
    Oddometer:
    512
    Location:
    Australia
    Sounds like it's very lean at idle. You shouldn't have any leaks through the slide cap, even if the seal is broken or missing. More likely the rubber carb mounting boot is cracked or leaking at the joint where it bolts to the barrel. Less likely but not impossible is a leak at the base gasket or the joint between the case halves.

    Does it respond to changes to the mixture screw setting? The lean condition should improve as the screw is turned in, and vice versa. If it doesn't run rich enough even with the screw all the way in and you're sure there are no air leaks check the pilot jet. These have a very small orifice that is susceptible to gumming up. If there's any doubt about it fit a new one.
    #2
  3. rjmorel

    rjmorel Dual Sporticus

    Joined:
    Oct 31, 2005
    Oddometer:
    534
    Location:
    Walla Walla, WA
    More likely the rubber carb mounting boot is cracked or leaking at the joint where it bolts to the barrel. I'll take it off and give it a good look.
    Less likely but not impossible is a leak at the base gasket or the joint between the case halves. I replaced piston , rings ,head and base gasket but will further rcheck them with leak down test for leaks.

    Does it respond to changes to the mixture screw setting? No ,haven't been able to get it running smoothly enough to fiddle with the air screw, hard to keep running and adj screw at same time.
    The lean condition should improve as the screw is turned in, and vice versa. If it doesn't run rich enough even with the screw all the way in and you're sure there are no air leaks check the pilot jet. These have a very small orifice that is susceptible to gumming up. If there's any doubt about it fit a new one.
    I did ultrasonically clean carb over night and ran a wire thru the orifice but may need to revisit it as well. thanks for the ideas. rj
    #3
    shinyribs likes this.
  4. snarlyjohn

    snarlyjohn Human money repellant

    Joined:
    Apr 1, 2016
    Oddometer:
    512
    Location:
    Australia
    While you're at it check the two small holes that run from the pilot jet into the carb throat.
    #4
  5. rjmorel

    rjmorel Dual Sporticus

    Joined:
    Oct 31, 2005
    Oddometer:
    534
    Location:
    Walla Walla, WA
    will do
    #5
  6. rjmorel

    rjmorel Dual Sporticus

    Joined:
    Oct 31, 2005
    Oddometer:
    534
    Location:
    Walla Walla, WA
    Looking at it today the small holes in carb are all clear.
    Should there be an O Ring on the pilot screw down inside under the spring?
    Took off the manifold , no tares but the flat mounting surface that mates to the cylinder must have a .020-.040 concave dish in towards the center hole. I put some mega-black gasket silicon on between cylinder and mounting surface of manifold and bolted it back together to see if it seals.
    Need to let it sit a day to dry. Not sure if it leaked there but it can't hurt.
    #6
  7. Euromad

    Euromad Been here awhile

    Joined:
    Feb 16, 2010
    Oddometer:
    581
    Location:
    Lower Slobbovia
    There is usually an O-ring on the fuel screw. Must be Viton. When you have it running spray carb or brake cleaner on all the carb joints, connections, head. If there's an air leak the revs will change. It will bog or race depending on what you spray. If you don't find it, pull the head and make sure there isn't evidence of blowby.
    #7