problem need help

5 replies to this topic
  • wswain

Posted November 15, 2007 - 02:53 AM


hey guys i just purchased an 04 yz450f 2nd hand but in excellent condition. do not grill me as ive searched this forum alot. the bike hadnt been ridden for awhile and was stored do to the previous owners job.

we unloaded the bike, fired it up with choke , took like 2-3 kicks and fired right up, but i have 2 problems.. whenever i went to go it would ride abit eg 10 metres down driveway then stop, then i rode it down the road then stop, then in paddock and stop( it would just die). i dont know what the problem is ive drained the old fuel and put new fuel and it still does it , tomorrow im getting a new plug and changing it but for now i wanted some help. it is also backfiring when i let the throttle off.. i was told by a mate it could be the cam chain..
any help appreciated
thanks will

  • grayracer513

Posted November 15, 2007 - 05:29 AM


Read this:


Then check the fuel screw adjustment, the operation of your hot start, and the condition of your pilot jet, in that order.

  • wswain

Posted November 15, 2007 - 07:32 PM


thanks i will get back to you once i find out the problem or rule out one of the things you mentioned... i took the plug out and it was very old, put a new 1 in still same problem. but the guy had a different plug because he rode it at a different altitude etc. in north(qld) aus where im in east aus(nsw).. would that have mad him change anything

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  • wswain

Posted November 15, 2007 - 09:36 PM


hey ive got another question for you greyracer.. we fiddled around with the idle and it seemed 2 improve the whole running off the bike. eg no stoping and less backfiring when deacclerating but my dad thinks it is still running abit rich. what would i need to do to stop this? in the manual which 1 is the fuel screw , we searched through it and found the carby diagram and all the stuff but it doesnt directly say "fuel screw"?? im getting a mate 2 have a look at it and his opinion. but any help appreciated.

  • grayracer513

Posted November 15, 2007 - 10:13 PM


Look in section 3, page 17 or so, "Pilot Screw Adjustment"

If you remove the pilot fuel screw to replace it, be aware that there is a spring, a washer, and an O-ring (in that order, from bottom to top) up in the bore. Use them on the new screw unless it comes with its own. The O ring may stick in place.

  • wswain

Posted November 16, 2007 - 04:10 PM


ok thanks.. hopefully we can get it sorted out this week if not i might take it into my local dealer and get them to have a look so i know its all good.. its running alright but not 100%..if u ever come 2 Aus and wanna ride let me know

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