2004 wr450 carb, jets, airbox and pipe questions

1 reply to this topic
  • 300lbsgorilla

Posted July 21, 2014 - 04:45 PM


I just aquired a 2004 wr450f and it has some mods to it.  I have some questions about making sure they are correct. 


The grey wire and the throttle stop have been done.


The snorkel has been removed but the holes under the side cover have not been cut out.


The needle is not stock as there are multiple clip positions however I can't tell what it is as there are no markings or color codes on it at all.  It is currently in the center (3rd) position.  The main is a 165. Has extended feul screw but don't know which make. Didn't get to other jets but I figure since the rest are not stock neither are those.  Bad assumption I know. The air cleaner will be a uni twin air.


The hot start cable is not in the carb.  There is a plastic bolt filling the hole under which is a strong spring and something removalble below that,  I didn't take it out so can't be sure.  The bike seemed to fire up easly after being run although I wouldn't say it was hot.  Should I replace the hot start?  It still has the plastic barrel so if I should I would need the aluminum replacement correct?


The pipe currently on there looks to be a yz titianum pipe but I am going to replace it as it does not have a spark arrestor.  I also have a FMF q silencer but I don't know the model as again no other markings other than the sticker and the USFS approved stamp on the tail end.


The header pipe has been crushed and resricted near the head.  It will be replaced with a FMF power bomb SS header as it was on sale.


Current setup seems to run good but was not an extended test drive.  Want to change oil and header pipe and back tire before I do too much riding on it.


So questions:


Should I cut the airholes under the side panel? 

If I cut the holes would a 165 main be enough with the power bomb header and the FMF pipe (not sure if I wil remove the insert or not for the noise.  I don't care much for very loud bikes.)  would it be right without the hols cut?

What about the hot start?



Saved the best for last here.  When I was checking the needle I noticed what seemed like a lot of slop in the slide.  How much is normal?  anyway to measure it to be sure it is in tolerance?  If out of tolerance is there a way to fix it other than a new carb?


Like I said right now it seems to run strong and has a lot of snap, but no long rides to really sort it out.


Thanks for any help you can provide.



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  • Krannie McKranface

Posted July 21, 2014 - 05:13 PM


If you can dial in the idle, and it  stays there hot or cold, no hang, no blubber, your slide is fine.

It's the Needle jet (that the main screws into) that wears first. It ovals out.


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