Just bought a 2003 WR450, several questions

10 replies to this topic
  • going up

Posted July 27, 2015 - 12:13 PM


I am sure with some more research on this site I could find my answers but thought I would just ask.

I just bought a 2003 WF450f.  Big step up from the TTR230 I had.

For now there are just a few questions I have:


1.  Is the knob on carb a choke or primer?  I have never seen a choke you have to hold open like that. Seems like a trick to kick start and hold the choke open at the same time when the battery is dead.  Am I missing something here?


2. The bike seems hard to start when it is warm.  I was out over the weekend and several times after running for a while and turning it off. When I would go to restart it would take 5-10 tries to get it to start. Cracking the throttle a little would sometimes help.  Once I had to crack the throttle and hold the choke open.  This doesn't seem to make much sense when it is warm.


3.  Is there a good location for free download of service manuals?


4.  The chain seems awful loose.  What is a good way to set or test  the chain tension?


Thanks in advance


Any other suggestions of cheap and easy mods for this bike?   I just use it for trail riding with the family. I am more concerned about dependability than squeezing more performance out of it.  (For now that is)

  • toten

Posted July 27, 2015 - 12:35 PM


Knob is a choke. On mine it stays out by itself. 


There's a hot start lever mounted near the clutch lever. Were you using it? I don't tend to but I figure it's there for a reason. 


Owner's/Service manual should have chain info, if you don't have one I'd highly suggest picking one up - they can usually be found cheap on ebay etc. Example: http://www.ebay.com/...eabdf2e&vxp=mtr


edit: I think it's Yamaha Australia that has the pdf available but it isn't as good as the paper copy - less information in the pdf. 

Edited by toten, July 27, 2015 - 12:37 PM.

  • Scoutman76

Posted July 27, 2015 - 12:57 PM


As was mentioned previously,   it's a choke knob and it should stay out on it's own.   Something is funky there.   I just picked up an 04 and am going through the bike piece by piece,  so I have had many of the same questions you have or will have.   The pinned threads at the top of the WR450 section here are invaluable.   The PDF manual is a bit of a pain to get through due to the different languages,  but it certainly works.   The link is below.




  • Krannie McKranface

Posted July 27, 2015 - 01:29 PM


Without knowing what jetting you have it's hard to give complete answers


On a bike that old you should assume the entier carb needs rebuilding due to corrosion, even if it idles.


1. You choke plunger needs a new oring

2. You need an R&D fuel screw and learn how to use it

3. Yamaha has free manuals

4.  Adjust the chain so it is barely taught and the longest arc of the suspension. You can do this by compressing the suspension with friends, or with tie-downs. 


You really need to read the FAQ section on your bike, as it has a SERIOUS recall notice regarding the starter mechanism.

  • going up

Posted July 27, 2015 - 01:32 PM


Thanks - I downloaded the PDF manual,  that should be very helpful


I will have to check into the choke knob to see why it will not stay out on it's own.  I thought that was strange.


I had not seen the 'Hot Start' lever, I will have to give that a try, I bet that will take care of the starting issue.  

Edited by going up, July 27, 2015 - 01:39 PM.

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  • toten

Posted July 27, 2015 - 01:44 PM


Speaking of the recall, is there any way to tell if it's been done on a given bike?

  • Scoutman76

Posted July 27, 2015 - 02:40 PM


Speaking of the recall, is there any way to tell if it's been done on a given bike?

My understanding is that if your Idler Assy Cover is flat,  then it is the original 2003 configuration.   All updated Idlers 2004- 2007 had a raised portion in the middle of the cover.   Pretty thurough discussion on the topic here..


  • DeepPurplishBlue

Posted July 27, 2015 - 06:38 PM


You really need to read the FAQ section on your bike, as it has a SERIOUS recall notice regarding the starter mechanism.


After 12 years if it hasn't let loose by now it probably isn't going to.


However, the key word is "probably"     It is of course not a 100% guarantee that it will never break, so

if you want to eliminate the "chance" that it could still let loose one day then the starter upgrade would

be something to consider.     


In any event the updated parts are worth installing anyway due to the improved design unless budget is

a problem.

  • Krannie McKranface

Posted July 27, 2015 - 06:58 PM


If the bike has never been short shifted under load, or stalled in a high gear going up hill, the problem will not have shown up.


If you ever do those, however, it will shear.


Now is the time to prevent it from happening.

  • toten

Posted July 27, 2015 - 07:32 PM


Why is it only likely to show up at low rpm/high load? For some reason I thought it had to do with the starter... My bike appears to have original parts but it's never been ridden on knobbies (the factory tires still have tits on them), only on 17s.

Edited by toten, July 27, 2015 - 07:34 PM.

  • going up

Posted July 28, 2015 - 12:13 PM


Thanks for all the information guys, very helpful.  Sounds like I have some research to do on the starter and need to go thru the Carb. 

I did get out and ride last night and made use of the Hotstart Lever.  That worked great. 


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