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Starting troubles

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asking the experts for help


quick summary of situation

  • bought a used '07 CRF450X to start riding with my son
  • first stop was to the dealer to check mechanical and valve job
  • rode once with no problems
  • bike sat for 1 month, then could not start...having been chasing ghosts ever since


quick summary of me

  • i rode as a kid.  first bike in 20 years
  • average mechanic skill - i have more confidence than skill, gets me in trouble

the gory details

  • bike sat for 1 month while my son was injured
  • during this time, i replaced the radiators
  • bike wouldn't start so i started on my journey from hell
  • i've read so many posts my eyes have crossed


    • confirmed have good spark
    • replaced plug just in case
    • havent checked since i'm only 3 hours after a valve job
    • havent checked decompression because no change in resistance on kickstarter
  • FUEL
    • replaced old gas with clean gas
    • cleaned carb and re-installed - no luck
    • installed new jets and re-installed - no luck
    • choke and hot start cleaned - no luck
    • confirmed good flow from tank to carb
    • confirmed carb passages clear
    • have not confirmed AP squirt (not sure how to do that)
    • tested Fuel Screw from 1 1/4 to 2 1/2 turns
    • tried using Starter Fluid and the bike tried to start but wont keep running
    • ended up messing up the Starter (squeals)
    • starter motor spins fine but make noise
    • TO DO: replace brushes
    • confirmed Starter Clutch is good
    • confirmed reduction gear not separated

since the bike sputters with Starter fluid, i believe its got to be fuel.


any ideas are appreciated

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If it was mine i would start with the fuel side of things again. Mainly the pilot circuit. New jet and make sure passage above jet is clear. Using fishing line / wire. Gas nowadays sucks and wouldn't surprise me if the carb is all clogged up.

Secondly check spark which you have done. Pull plug and check spark visually.

And lastly go over the shops valve job. Horrible cold starting is a usual sighn of tight intake valves. Did they cut the new valves in correctly or just do a backyard type of install.

Hope ya figure it out. Let us know.

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 I think fuel to, but one over thing I'd look at is with the valve cover off, double check the timing.  It's possible it may have jump a tooth.   Not probable given what you said, but possible and easy enough to check.


 But anytime I hear "it ran fine, then sat, now it doesn't run", it's always fuel, unless there is a mouse in the picture<g>


 BTW, do you use fuel stabilizer? and ethanol free or no?   If no and no, clean the carb again<g>



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The noise while starting sounds like it's your starter clutch, not brushes. Very common. Just did mine a couple months ago

Def a fuel problem though. Go back to carb and clean again. Replace the ap diaphragm and make sure you have a squirt.

Remove subframe and air boot from carb. Use a flash light to look through carb while you crack the throttle. You should see a squirt of fuel go into your head that just misses the slide.

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