HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
jaredwhite1212

03 Yz450f wont run please help

3 posts in this topic

Hello everyone I am new to this forum and have heard it is one of the best, which is why I came here to ask you all for help.  I have a 2003 YZ450F that was just rebuilt.  The bottom end was redone bearings and all.  The bike just will not run.  It is dead on timed, it has spark (or when the plug is out of the cylinder and i kick it over it does) and it is getting fuel.  for some reason even with those three things, it barely will ever even pop when i kick it.  i am all out of guesses and am hoping you guys can help me.  It has a lot of compression too. Anyone ever have this problem before or have any advice on things to check?  all connections seem to be good.  I have tried everything and am all out of ideas.

 

Thanks,

 

Jared

Share this post


Link to post
Share on other sites

If the bike sat for a time, especially during the summer, it may well have a blocked pilot jet.  All it takes is a dried film of varnish, even one that leaves the main orifice mostly open, and the bike will barely run.   My own '06 pulled this on me after the top end work I just did.  The orifice in the number #45 pilot jet in mine is supposed to be .018".  It was nearly impossible to start, and was in fact impossible to keep running.  A .016" drill would pass through the jet, but the .018 wouldn't.  That was all it took. 

 

Always worth checking.  The fuel you see on the plug may well be from the accelerator pump and or starter circuit.

Share this post


Link to post
Share on other sites

ok thanks for the reply. i will check all of the jets in the carburetor as it did sit for a while.  I was also told that it could be a throttle position sensor gone bad, but i have read forums about people unplugging those and the bike would still run

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0

  • Similar Content

    • By shawn denham
      i have a 2000 yz125 and i just took off the clutch case and i dont know the torque specs for the bolt. does anyone know ?
    • By Raven01
      Hi , I'm new here and I just purchased a spoke tourque wrench kit  "Excel (TWS-210ANS) 7-Piece Adjustable Spoke Torque Wrench Set" for my 2008 Yamaha  YZF450, the front spokes are smaller than the 6 that came with the bike and the rear spokes are larger than the 7 that came with the bike (I bought it New) Does any one know what sizes the front and rear spoke nipples are? I can still stop my order and seek the correct size somewhere. I find it lame that they gave me the wrong spoke wrench.
      Thanks in advance,
      Brent
       
       
    • By Zachhanus2
      Hey guys I'm looking to buy a bike again I'm currently saving up, prob gonna go on Craigslist should I go for a yz 125 or yz 250f, if I were to get a 250f I'd spend around 3300 is my budget, and goes for a 125 as well, I kno most of the differences but from any of your guys experience what would u say
    • By Gray4ACause
      Hello everyone, you wouldn't believe the brain dead mistake I made. So I installed my crank into the right side engine case on my 02 YZ426F last night. (Keyword Night) Then I proceeded to install the left side engine case onto the crank and trans with the Tusk Crank Installer. All is fine and dandy until I realized I didn't put any Yamabond on the case halves.  Now the left side case will not come back off the crank for the life of me. Note: The first time I split the cases the left side case came off without any hiccups. I am using the splitting tabs built into the case by the way. Does anyone have any tips? Also, why is the left side case being so stubborn this time? I hope I don't have to order a case splitter, those tabs saved me $70!
    • By Zachhanus2
      Hey guys I was wondering what bike I should get I havnt rode since I was in 7th grade but I had a kx 85 so I was experienced with riding I could pin the bike on tracks so I'm not completely new to riding now I'm 6,2 190 I was contemplating what bike to get, should I go with a yz 125 or should I go with a yzf450, I would never sell the 450 prob have it forever thank you tell me your opinions plz!!