03 WR 450 problems


11 replies to this topic
  • WR450_Rider

Posted July 01, 2010 - 08:44 AM

#1

I have an 03 450 that i bought new. The bike doesn't have much time on it at all. This spring I thought I would try re jetting it to take care of a low throttle opening stumble. Well i put in the jetting recommendations that I got off of this website and the bike runs terrible. I don't think its the new jetting because i put in the old jets and it didn't change. I have pulled off the carb several times and cleaned it meticulously. I know its not a passage or a circuit clogged in the carb itself. Basically the bike wont run off choke. whenever i take the choke off it backfires constantly and wont idle. To me it seems like there's a vacuum leak somewhere. I checked the intake boot and it looks fine. I also checked the vacuum diaphragm on the side of the carb and it too looks fine. Does anyone have any suggestions before I take it to the dealer and pay $60/hr?

  • jayh300

Posted July 01, 2010 - 10:14 AM

#2

hard to say for sure... couple of things i would check if it were mine...
hot start plunger and nut where it goes into the carb... have heard the plastic nuts crack easy and or threads strip... have also heard the plunger can stick..
fuel tank cap and vent can clog and not deliver fuel ...(have actually had one do this)
make sure #11 in this picture is in correct and not cracked.
http://shop.thumpert...2003&model=5223
sure sounds like a pilot jet/passage issue to me, but i am sure no expert....
hope you find it..
jay

  • WR450_Rider

Posted July 01, 2010 - 11:00 AM

#3

Thanks for the reply. I replaced the plastic nut and the o ring for the hot start. I haven't checked the vent tube. I will also check to make sure that #11 is installed correctly. I know it sounds like a clogged fuel circuit but I have cleaned it probably 5 times to be positive that there isn't anything clogged.

  • CORider63

Posted July 01, 2010 - 11:07 AM

#4

May want to check your valve clearances and make sure that your carburetor boot is not loose or cracked, as well.

  • jayh300

Posted July 01, 2010 - 11:08 AM

#5

i doubt it would be the fuel cap, but easy to tell... just open the cap a half a turn so it can breathe... i doubt that is it, but who knows....
have not had much luck cleaning clogged pilot jets, but you said you replaced it also...
it is gonna be something wierd at this point.... at least it would be on mine...
jay

  • jayh300

Posted July 01, 2010 - 11:09 AM

#6

May want to check your valve clearances and make sure that your carburetor boot is not loose or cracked, as well.


for sure on valve clearance.... can sure make them not idle....

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  • tribalbc

Posted July 01, 2010 - 11:16 AM

#7

Replace your pilot jet. It's too small to clean properly.

  • mjslim

Posted July 01, 2010 - 01:01 PM

#8

One other thing you can check. It is possible for the choke plunger to get bent and cause a vacuum leak at the plunger shaft seal. Had this happen to my '03. Spin the plunger knob and see if it wobbles. If it does, replace the plunger assy - costs $15 or $20 at the TT OEM store.

  • PBDBLUE

Posted July 01, 2010 - 01:55 PM

#9

Check the slide plate and make sure you did not assemble it upside down. The plate goes on the engine side of the slide with the cutout facing down.

  • bg10459

Posted July 03, 2010 - 04:36 AM

#10

Check the slide plate and make sure you did not assemble it upside down. The plate goes on the engine side of the slide with the cutout facing down.

My thoughts, exactly. If the bike ran good before and the carb is clean, then something isn't assembled right. An upside down slide will have the symptoms of a too small or clogged pilot jet.

  • WR450_Rider

Posted July 05, 2010 - 08:49 AM

#11

Turns out the slide plate was on upside down. After switching it the right way my problems are solved. Thanks for your input!

  • jayh300

Posted July 05, 2010 - 08:57 AM

#12

Awesome... glad you got it fixed




 
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