wr450 exahust and jets?

19 replies to this topic
  • barefootbob

Posted December 02, 2004 - 03:07 PM


I,ve had my 04 wr450 for about 6 months{my last bike was a kx500} I.ve done the normal up grades new exhaust tip shorten the throdle stop and the grey wire 1st thing.Rode the bike for a while but still hungry for more abuse. After reading on this site for a while lookes like the fmf Q will be the exhaust I will use and I will make the craddel for the battery to open up the air flow but the jetting is still a mistery I live in northern Ca. I ride mainly at cow mtn. and Elk mtn.{cc camp}elev.2000 to 4000 What brand and size jets should I buy.My local dealer says I need new cams along with the exhaust and jetting but cant tell me what size jets they will use.I really dont think they know.Dont want to be messing around with testing just want to ride.

  • Jackazz

Posted December 02, 2004 - 03:17 PM


My 2¢ would be to get an easily adjustable fuel screw & a jet kit,first. If you've done the rest of the "free mods" & ditched the exhaust cork (if you are allowed to make that much noise) & you have your fuel screw adjusted & the jetting dialed in you might not be in such a big hurry to spend a bunch of $$ on a new pipe.

  • WR450F_RDR

Posted December 02, 2004 - 06:07 PM


I wouldnt recommend the FMF Q, not much better than stock exhaust or an insert, I would go with the Powercore IV and get the silent insert for when you need it. I wouldnt do any kind of cam mods just putting after market exhaust on it, sounds like they are trying to sell you something. I use the Powercore IV and am very happy with it, definite improvement over stock, my jetting is: 168mj, 48pj, 4-clip position (JD jetting another good recommendation), I ride at anywhere from 1500 to 5000 ft here in southern Oregon, I would also recommend something along the lines of Zip-ty racing fuel screw, makes jetting a whole lot easier.

  • Indy_WR450

Posted December 02, 2004 - 07:04 PM


Ditto! Powercore IV with optional insert :cry:

  • fsott

Posted December 03, 2004 - 07:07 AM


I have an 05 and I am going through the jetting process. I put on a Big Gun exhaust and have gone with a 52 pilot jet (per the dealer), 170 main jet, and ty air adjustment screw. I am real close. I will ride this weekend and let you know how it went. The power has doubled when I tested around the neighborhood last night.


  • Gadsen

Posted December 03, 2004 - 07:34 PM


Ditto! Powercore IV with optional insert :cry:

Indy, OK, help me out here. I'm going to get a new muffler for my new WR450F, was considering the "Q series" but after the comments here, would consider the Powercore IV. OK, I've found the Powercore IV SA which is "spark arrestor", what is this insert? Is it for noise reduction and what is tne noise level with and without this "insert". I like the "bark" but do want to keep it 96 db or less. :cry:

  • WR450F_RDR

Posted December 03, 2004 - 08:38 PM


The SA is a screen insert put in the end of the muffler, the Quiet core is an insert you can put in the muffler, along with the Spark arrestor to quiet the muffler down a bit. I have been tested at 98db without the insert and at 93db with it, I have just recently repacked my muffler which helps with the sound levels.

  • Gadsen

Posted December 03, 2004 - 09:05 PM


OK RDR, onemore question, well, two more then! :cry: Can this muffler bolt right on the existing pipe, or will it require an FMF mid pipe or header pipe? And the last question for now :cry: DId you have to rejet the carb, or did it work OK with the stock jetting? The 93 DB sounds good to me. :cry:

  • WR450F_RDR

Posted December 04, 2004 - 07:45 AM


The pipe will fit without any kind of adapter, just clamp on. I did rejet and you will want to in order to get best performance, this slip-on muffler is a big difference over the stock unit. My current jetting is 168MJ, 48PJ, 4 clip position on needle (JD jetting, also another great recommendation) and my fuel screw varies from 1-1/2 to 1-3/4, I would also recommend a Zip-Ty fuel screw or similiar as it will making jetting very easy. I ride from 1500ft to 5000ft in altitude.
and excuse me for jumping in on the answers for you Indy. :cry:

  • WR450_in_Turkey

Posted December 05, 2004 - 12:08 AM


Just fitted a Powercore4 and a home made quietcore to my '03 wr450. I have played around with the jetting a bit and ended up back at the standard setting for an EU model. Main is 160, pilot is 48 and the pilot screw is a tad over 1 3/4 turns out as I prefer it to be slightly richer than leaner off the bottom. The EU spec carburettor is different to the US one due to our (slightly) less restrictive emission laws! Ride area here is between sea level and 2000ft. Yesterday was the first ride with the new setup and difference is unbelievable!!!!!! over stock. Plug colour is fine on the overall ride so I dont think it needs much more work. BTW thanks to Indy for the quiet insert dimensions.

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  • Alabama_Rider

Posted December 05, 2004 - 12:39 PM


Finally got some play money to upgrade my 450. What did you get the most return on.. How do you like the Magura and Ohlins? What about the 3.3 tank? Does the cap sit higher than stock, & jam ur ....

  • Indy_WR450

Posted December 05, 2004 - 06:02 PM


Hey Alabama Rider get the Ohlins first! Your rear end will track and maintain contact with the ground like never before! I was amazed at how much of an improvement it was over the stock shock with a heavier spring. Ohlins actually has a high speed and low speed circuit that you can feel and works wonderfully well. I can ride up nasty rooted rocky terrain without loosing momentum from not having the wheel in contact with the terrain. The rear rebound is extremely lively at low speed and wont let the rear wheel take air over sharp obstructions. The stock shock almost feels dead at low speed compared to the Ohlins! :cry:
I love the Magura Jack clutch! :cry: I have had it on for a year and a half now and love it. I wont go back to cable again. :cry:

Sorry I cant post all my mods on the new reduced signature format of this forum but here is a list of what I have on the bike and I cant make any complaints on any of the mods:

[COLOR=Sienna]2003 - WR450F - Cost $ 6,400.00 (new)[/COLOR]

Current Mods:

Scotts Steering Damper
BRP Triple Clamp
JD Jetting Kit
Ohlins 46PRXW - 5.9KG Rear Shock
MX-Tech Front Fork Off Road Valving
Magura Jack Hydraulic Clutch
Spare Wheels Excels/Bull Dog/Talon Hubs/Wave Rotors/Ironman 50T Sprocket
(Rocky condition tires on spare wheels & soft terrain tires on stock wheels)
Hinson Billet Clutch Inner & Outer Hubs & Stock Plates
GYTR - 3.4 Gallon Fuel Tank
FMF PowerCore IV SA/2"/Quiet Core
FMF Power Bomb SS SX Header
Boyesen Water Pump
Power Now & Power Now Plus
Trail Tech & Billet Mount
Twin Air Filter with Air Box Cut Out Mod
Pro Taper Bars with Rubber Mounts
Trick Dual Sport Kit
TM Designs Chain Buffer (with 1/2" Thick Silicone Protection for Swingarm) & Guide Block
SS Braided Honda Routed Front Brake
Carbon Fiber Fork Lower Guards
Seal Savers
Devol Rad and Frame Guards
Works Connection Skid Plate & Rad Braces
Acerbis Rally Pro Bark Busters
Ironman Sprockets 13/14/15T fronts / 50T Rear
Regina ORN 520 O-Ring Chain
Progressive Suspension Brake Snake
Zip Ty Fuel Screw & Magnetic Drain Plug
Icat ignition & NGK CR8EIX Iridium Spark Plug
04 Starter Upgrade
Grey Wire & Sky Blue Wire Mods

[COLOR=Sienna]Estimated Costs of All Mods: $ 6,000.00 (new)[/COLOR]

  • 450_James

Posted December 05, 2004 - 06:42 PM


Indy you bring a tear to my eye... :cry: That's just beautiful. :cry:

  • Indy_WR450

Posted December 05, 2004 - 06:47 PM


Yeah it all sounds good but the bike really is a war pig. :cry: No graphics and plastics that looks like they went thru hell and back! But the bike runs better than new! I am not into apperances. I just want the bike to perform very well. :cry:

  • Alabama_Rider

Posted December 05, 2004 - 10:09 PM


Wow, a dream bike.... You must ride every weekend. If you ever come South let me know we will hook up. Sounds like the first place to start is the Ohlins. Is the FMF better than stock without the baffle. Is it much lighter? Do you ride more open country or tight woods? I am sure I will have lots of questions coming... My biggest complaint now is the stock fork. What have you learned?

  • Indy_WR450

Posted December 06, 2004 - 03:42 AM


I will be getting down to Alabama and riding in the Talladega National forest (Kentuck ORV) around the last weekend in January with TT buddy Mike Hudson. I will PM you when we schedule it. We are riding Durhamtown this weekend if you want to come over and hook up with us. I ride everything from tight woods to wide open desert. I like the variety. :cry: :cry:
The FMF pipe is an improvement over stock uncorked but honestly it is hard to justify the cost over spending the same money on suspension. Yes it saves 4 or 5 lbs but it really does not give you that much more power. The bike already has enough. I like the FMF set up I have because it gives me more bottom end grunt right off idle over stock uncorked. The bike can be run in a taller gear in the woods without stalling. When it is real slick and wet in the woods I can put it up into 4th and be lugging it just above idle and it wont stall. Big help when conditions are real slick. :cry:

The stock front forks were not plush enough for me. I sent them in to MX-Tech and had them revalve and rebuild my forks after running the stock set up for a year. What a difference. I rank suspension work front and back number 2 on my list of mods. Number 1 is getting a steering damper and raise the forks 15mm in the clamps for better tight woods turning. The stock geometry only works for animals like Scott Summers in tight woods. :cry:

  • Alabama_Rider

Posted December 07, 2004 - 01:35 PM


Thanks, I ordered the Ohlins and it is here.. Was I supposed to get a mounting kit with it? I also ordered the FMF.

Ebay has an Ohlins Fork set which came from the Cannondale liquidation. I wonder if these could be modified for a WR?

PM me when you go to Talladega.. You will enjoy it but it is rather open. We ride much more technical in lower Alabama.

  • Alabama_Rider

Posted December 09, 2004 - 11:28 AM



I have run into a mounting problem with my OHlns.Do you have the complete part number for yours....

  • Indy_WR450

Posted December 09, 2004 - 12:25 PM


The Ohlins 46PRXW is made in several sizes to fit different bikes.

I use the 46PRXW - 29-5073 - 5.9kg made for a YZ450 2003 model

I hope you got the right length model. PM me with your phone number so we can compare lengths tonight.

  • luke_n

Posted December 11, 2004 - 10:55 PM


So who's is bigger :cry:


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