03 wr450 jetting


8 replies to this topic
  • GregB

Posted August 05, 2004 - 10:24 AM

#1

Should I be able to snap the throttle open from idle' or just above idle without it bogging, and stalling. Have all the free mods and GYTR insert. Current jetting is 50 pilot, 162 main, #5 groove, 3 turns out. I had the carb off and the a/p seems to be pushing enough fuel. I am saving for the JD kit, but want it to run good for now. It runs great if I quickly roll the gas on, but falls on its face if I snap it. Any help would be appreciated.

  • WR450F_RDR

Posted August 05, 2004 - 12:11 PM

#2

I would seem to me that maybe your main jet and clip position are a little high and 3 turns out (is this on fuel screw?) or mixture screw?) for just using an insert, if you had after market exhaust you could run them higher. I would try a slightly smaller main and go down on clip one position, another words I think you are running a rich. if you do a search on bogging you will find a wealth of info.

  • mtrablue

Posted August 05, 2004 - 02:32 PM

#3

what elevation are you at? your jetting sounds very rich on the bottom. i'm at 700ft and run a 45 pilot and a 160 main in the summer. two turns out on the pilot fuel screw. i did put in a smaller leak jet but the differance was small. is this your first thumper? you just can't snap the throttle open from idle in the driveway and expect it to rev instantly. you can get it close but you've got a lot of stuff spinning around in that motor. it just won't spin up like a two stroke. the big question is how it runs when you ride it. if it bogs when you ride it, you've got some work to do.

  • RichBaker

Posted August 05, 2004 - 03:04 PM

#4

Is this on the stand or riding? Trying to sort out jetting without riding is a waste of time....
It does sound like you're too rich on the bottom, though...I'm at 2700' and have a 45pj, 162mj, 04WR needle on the middle(4th) groove and functional ACV. Stock exh. w/GYTR insert.
3 turns out on the fuel screw(which IS the mixture screw...)is too much, they've been lost with 3 turns...

Should I be able to snap the throttle open from idle' or just above idle without it bogging, and stalling. Have all the free mods and GYTR insert. Current jetting is 50 pilot, 162 main, #5 groove, 3 turns out. I had the carb off and the a/p seems to be pushing enough fuel. I am saving for the JD kit, but want it to run good for now. It runs great if I quickly roll the gas on, but falls on its face if I snap it. Any help would be appreciated.



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  • WR450F_RDR

Posted August 06, 2004 - 04:20 AM

#5

well we need to define whether he is talking about the pilot screw which a lot of people call the fuel screw or the idle mixture screw, either way 3 turns out seem a bit rich, my pilot screw is only 1-3/4 turns out.

  • GregB

Posted August 06, 2004 - 07:38 AM

#6

I started with a 48 pilot, mixture screw at 1 3/4, 158 main jet but it did the same thing. When riding it falls on its face when I twist it hard from low rpm's. I thought it was lean because if I pulled the choke out it ran perfect(of course it idled rough, but not bogging). I had a XR400 with some mild motor work. I know I couldn't just wack the XR open from idle, but it did not have an accelerator pump. I ordered the JD kit yesterday in hopes it will resolve the problem. I was just wondering if I was way of the mark or not. Thanks for yor help so far.

  • lipskid

Posted August 06, 2004 - 01:08 PM

#7

Greg- You might try a smaller leak jet(w/48pj). When I opened up my air box w/ aftermrket pipe, the off idle bog got a lot worse, a smaller leak jet (stock '03 YZ size, sorry, can't remember the # right now) fixed it for me. :thumbsup:

  • RichBaker

Posted August 06, 2004 - 02:29 PM

#8

well we need to define whether he is talking about the pilot screw which a lot of people call the fuel screw or the idle mixture screw, either way 3 turns out seem a bit rich, my pilot screw is only 1-3/4 turns out.


Ok...where is the "mixture screw"? The pilot screw is the one Zip Ty and everyone else makes a replacement for, correct?

  • GregB

Posted August 06, 2004 - 03:52 PM

#9

I'm gonna try the 48 pilot again, drop the main down to 160, and start with 1 1/2 turns out. I'm gonna take it out on Sunday to the track and do a little test & tune. I' ll let you know how it turns out. Thanks, Greg




 
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