2003 Yz85 Bogs down or dies - why and what am i doing wrong?
  • Jammj
    Posts: 21
    Hello, yes this is my first post here at Dirt Rider.  Hope I feel welcomed here.  Let me introduce myself really quick. 

    I raced on a Yamaha zinger 80 when I was 11 years old back in 1983 - Picture is example.
    imagehttp://p1.bikepics.com/2007\01\19\bikepics-775473-320.jpg

    anyways, 29 years later, I got back into riding dirtbikes and got my daughter a yz85. 

    Heres the problem -

    when i first got it, it will die/bog out when choke is down,  I have to pull the choke and ride.  It will not go into powerband and bogs. 

    I took the carb out and cleaned it, it was dirt in it and got it looking spanking brand new.  I re installed the carb and started it up.   choke down, will idle but as soon as i let go of the clutch it dies.  Hell with it, put it in choke, ride it. 

    when its in choke, sometimes it will bog out, sometimes it will jump in powerband and scream!!   I dont like it like this because one time it caught the powerband and popped a wheelie.  I nearly soiled my britches. 

    The work that I have done - 
    • I have removed the black exhaust, and its clear.
    • Removed the carb and cleaned it
    • reset the air screw (bottom screw of the carb) to 1 and half turn
    • repacked the silencer
    • changed spark plug - not regapped yet - had the same issue before changing plugs
    • Cleaned air filter and put some yamaha air filter oil on it and sqeezed it out. - need new filter


    Now im thinking, okay, maybe the jet (i had to research it and find out what it is)  is still dirty?  do i need to overhaul the carb with a carb rebuild kit -

    http://www.ebay.com/itm/380492454648?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

    or should i get my kit somewhere else?  

    or does anyone know what the issue is?  My other 2 kids are riding pw80s and they are passing me while im jacking with this bogging down issues.  Starting to tick me off but to see my kids smiling faces when they pass me is priceless is why i cant stay angry.  But this is getting old.  Its gotta be fixed somehow. 




  • CRWOODS
    Posts: 448
    Have you checked the compression or taken a look at the top end?
  • Maple Leaf MXMaple Leaf MX
    Posts: 12,821
    Crwoods knows because he is js7's mechanic. U ready for a1 next weekend yet crwoods?
    Expect to die whenever but dream to live forever

    ..the good times on the old DR board will never be back! RIP!
  • CRWOODS
    Posts: 448
    Mapleaf is Mitch Payton's top mechanic so he will help you sort things out.
  • Maple Leaf MXMaple Leaf MX
    Posts: 12,821
    So r u ready for anaheim 1?
    Expect to die whenever but dream to live forever

    ..the good times on the old DR board will never be back! RIP!
  • Jammj
    Posts: 21
    Not yet on the top end. that was my next step.  I mean it runs when it wants to but it has to run in choke to make it go anywhere.  cant let the choke down or it will bog down  and die in first gear

  • cody12319
    Posts: 16
    when you cleaned the carb did you clean the jets too??
  • Jammj
    Posts: 21
    That is what I was thinking Cody, I cleaned all the passageways but unfortunately i didnt clean the jet (didnt disassemble it) and now Im going d'oh!!  I was going to wait and do everything at once. 

    I was going to take the seat out, take the gas tank off, drain it and clean it out really good.  Do a top end overhaul on the cylinder, take the carb out and rebuild it with a new kit that im getting from ebay. Change the oil.  Then finally pre mix the gas with premium gas with yamaha oil i got,  going to do 30:1 on it.   I will be doing this next week.  I ll post back and show the findings.
  • Jammj
    Posts: 21
    oh yeah, i found a service manual on line AFTER I cleaned the carbs.  I have printed them out and got it on hand.  Now i can do step by step and see.  I have top end and carb paperworks.  Im good to go. 
  • cody12319
    Posts: 16
    cool...glad to hear (:
  • Jammj
    Posts: 21
    heres an update, its been cold and rainy around here.  Today was a first warm up and a break in the weather.  I went ahead and took the carb out and disassembled everything.  Oh man, I thought it was clean enough but it was filthy.  Jet was all clogged up, and  pieces caked over.  you can see the hair and dirt in front of the pilot jet.  Now the carb has officially been cleaned and rebuilt. 
    Now i gotta work on the reeds to see if its in tolerance and i ll check it when i do a top end overhaul.  I havent ordered the piston and rings, etc yet.  Hang on.  I also gotta replace the back fender and sides (white).  I am also going to clean out the gas tank too.  Its off as well. 

    got some work ahead of me before i get to start it again.  

    image
  • Jammj
    Posts: 21
    it also had a little tiny groove around the rubber piece - float valve.  Yes i measured the float and its at .75 to .77.  Its within tolerance.  Yes i had to adjust it according to the service manual.
  • Jammj
    Posts: 21
    now when i took everything off, i can see the sub frame is tweaked a little.  *sighs*  I guess i need to order a straight subframe so i can put new rear fender on.
  • Jammj
    Posts: 21
    cleaned the gas tank out today and took the subframe off.  Definitely its tweaked.  *sighs* 
  • Jammj
    Posts: 21
    image
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