03 Yz450 tear down!!

24 replies to this topic
  • XR133

Posted March 09, 2009 - 06:58 PM


Didn't think to document with pictures, but I just finished a complete build of a 2003 YZ 450. Bought it in boxes for verrrry cheap. Crank bearing had seized and the kid that owned it had disassembled pretty much everything before giving up. He wasn't really in to marking what was what, so I spent a good deal of time figuring that out. Factory manual and this site were invaluable. New crank, all new bearings, a few other bits and pieces, and complete gasket kit was all it took to get it going. Everything else checked out okay. Fired it up tonight and rode it in the driveway and on the street in my neighborhood. Trying to take it easy, but it is very evident that it has a little more go than my XR400. Loving the reduced weight and better suspension, too. Hopefully it's as reliable as the XR. If I can get it broken in, I'm planning to race it in a harescramble in two weeks. Gotta' get a few woods essentials installed...

  • Chriswells85

Posted March 17, 2009 - 10:34 PM


No. Your bike requires a minimum US pump grade of 90-91. Detonation and possible severe engine damage can result from using lower grades of gas under the wrong conditions.

I check the pumps out a local gas station.. Looks like the supreme i put in it was 89 :) the next up is 93, would that run ok?

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  • ace402

Posted March 18, 2009 - 04:36 AM


Yes, 93 is just fine.

  • grayracer513

Posted March 18, 2009 - 06:18 AM


93 is above the minimum of 90-91, so yes, that will have enough octane. The fuel may or may not "run OK", depending on any or all of several other factors, but at least it shouldn't ping, which is all that the octane number tells you.

  • cheeseclip

Posted March 18, 2009 - 08:49 PM


when my 03 doesnt start after ive let it sit for a month or so i just turn off the fuel tap then undo the big nut on the bottom of the carb and let all the fuel in the carb drain out. then do it up, turn on the fuel and start as per normal

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