Help Calling all UK WR450 Owners!!

Hi ive just got a new old stock 2005 WR450F. Ive done all the free mods

1,Exhaust mod

2,Air box opened up

3,Grey wire disconnected

4,YZ throttle stop

The bike came fitted with a 45 PILOT,165 MAIN and a non adjustable Needle .In the spares bag it had a YZ Throttle stop and a 48 PILOT which i have fitted and an adjustable Needle which i fitted with the circlip on the 5th notch (from what i see on this site this is what most people have it on) But what i would like to know is what MAIN JET most of the WRs are running here in the UK.The bike starts and runs ok but is a little bit rough, what worried me is i got a glowing red hot front pipe fairly quickly in the garage!! and after doing the free mods it must be getting way more air so i dont want to ride it until i know more about the main jet. Many thanks .

had same on a yz426 ran lean as hell on idle,erratic and header glowed very quickly.try to richen it little bit on bottom.not ideal letting idle stationary very long but can be a worry exhaust starting to glow in matter of seconds.

Pop over to and have a look through the supermoto section, loads of UK info there. My advice would be to have it rolling road tuned, mine had an Akro full system on it and it came alive after proper tuning.

I always hear very good things about the JD jet kit also, worth looking into that also. :cheers:

Hey ive just brought a new 2005 WR450F. Done no mods, I thought it was all USA based? :cheers: so there is more power available?! i got the throttle stop screw and a jet and some dark thing that looks like it is off the exhaust system in a seperate bag. *confused*

This is my 2nd enduro bike, having put the gsxr 600 away for the winter wanting so fun on this. its kinda hard to start? about 20 kicks and im away

Im going to try a 168/170/172 MAIN and see how it is.Somone said on TT after the airbox mod you should go up 2 main jet sizes?That would be 170 . SAMPS if in your bag you have a 45 PILOT JET , a NEEDEL with one grove in it and a THROTTLE STOP screw longer than 11mm your dealer has done some derestricting for you. But check all the free mods are done lots more power avalible if not done,(see all the "free mods "threads ,yes they are for UK bikes) dont know what the dark thing is ,have you got the alloy oval tail pipe or the round stainless steal one?

Thanks for reply.

Oh right Chris i'll have a look through and see what exactly ive got in the bag. My exhaust as an oval one, smooth kinda design.I didn't realise there was 2 different exhausts?


In the bag ive got a black, screw thing with a HEX head this measures appox: 35mm in total length, non including the HEX fitment the screw measures approx:30-31mm. The thread part measures 6mm and is at the base of the screw.

A piece of hollow brass? total length: 28mm, has a thick section, with a thread 3/4 of the way up and a thin section with small holes (grouped in 2's) punched through it. printed on it: A STAR SYMBOL AND 48

A long needle type thing, approx 104-105mm in length, with 7 small grooves at the top.

A black hollow piece of steal. 46mm total length, and 13-14mm internal diameter. This piece also has a wrap of steal wedled in the middle and small holes punched through equally either side.

Ok why i mentioned the exhaust shape is because the oval is 2005 model ,but some dealers sold 2004 models registered 2005! .So round s/steal upto 2004 oval alloy 2005 on. It sounds like your bike has the yz throttle stop and exhaust mod fitted but apart from that is still in fairly standerd spec ie 165 main jet ,non adjustable needel and 45 pilot jet. What i have done is fitted the 48 pilot jet ,the adjustable needel with the small circlip on number 5 grove (5th from top) and bought a 170 main jet , once youve done all the free mods this makes the bike a king animal!!!!! i may have caused a problem by doing all of this because i now have trouble keeping the front wheel on the ground!!!!!!!!!!!!

Ok, just took the cover off to check the current throttle stop screw, on the bike from new is a silver alloy throttle stop, which measures approx 24mm in total length including the HEX fitment. The one in my bag is 35mm in total length and is black with pink locktite on the thread.

Im guessing this mod has already been carried out by the dealer?

Thanks, Ben

Up until 05, all the grey wire/throttle stop stuff was indeed all US based. But from 05 onwards we have the same deal so there are some free mods to be done.

You'll tell an 03-04 bike from an 05 by the smaller fuel tank amongst other things :cheers:

HI there,

Ive got a 2005 model 450 and Make sure you remove the emmisions crap, this will make the bike run miles better. I run a 170 main jet and my front pipe still glows, I reckon it must be kinda normal on these bikes. Also open up the airbox on the right side and pull out the grey wire hidden under the tank,I did all my mods at once which took about 3 hours including the jetting.

Once I had done the emmissions the bike stopped popping on decel and is now pretty quiet compared to my old DUKE 2 with twin G Force cans :cheers:

Oh and get some SM wheels coz there will be no offroading soon :p

Hi Farmerboy which grove on your needel are you running?

ive got 170 main 48 pilot 5th grove on needel, i have slight spluttering on half throttle crusing on the road. Going to change to 4th grove see if this helps.Apart from that the bike is awesome 1st 2nd 3rd wheelies on power easy, smooth everywhere else idle ,pick up and flat out. Done all mods including the AIS emmisions cr*p.

Right looks like im sorted! Just come back from a ride put needel on the 4th grove and no spluttering . The WR450F is just the best bike ive ever had ,big smile every ride! Thanks YAMAHA and thanks TT.Fantastic site an Aladins cave of infomation well done. Cheers Chris.

Yep the 4th Groove is the way to go From what I remember,

Half way through my 1000km service, only the valves and the rear swingarm and rear shock linkage to remove and grease and Im done.

SO far so good however I wasnt prepared for the metre long horizontal oil flow outta the frame bolt when i drained the oil After a moment of panic I got it sorted though.

The problem with the 450 I have found is the more you cane it the better it gets, It just keeps getting faster until I loose my bottle and shut off.

I bet its a hoot with supermoto wheels on round the backroads

ahhhh i need to do these mods. Im scared to do the grey wire, i don't wana loose any performance, did you cut it off or just pull it out of the connector?

you only need to do the grey wire mod on the 05 or later bikes

just take the seat and the tank off ( 10 mins ) then locate the wire block and pull out the grey wire from the correct side and tape it up, dead easy took me 20 minutes tops to do. There are loads of pics on here of what to remove, i cant post them though coz im only on dial up.

I found everything i needed on here in 30 minutes surfing, so for you broadbanders it should be simple.

any probs and ill help where i can

little off topic but has anyones water pump seal gone? and is it an easy fix? 2003 uk wr450f.

Hi All, I'm new to the site, having joined a couple of days ago. Can you please offer me some further advice on free mods and jetting? I have a stock 04 WR450, which having read through much of the information on here suffers from all the traits mentioned.

I'm going to do all the free mods and follow the guide on jetting. I have also read that changing the Leak Jet from the standard 50 to a 40 improves throttle response, making it crisper. Is this necessary?

I note that the grey wire is only found on 05+ models, so can I take it that my 04 bike is already running the YZ mapping? If this is the case I take it it will be ok to continue with all the mods and jetting?

As for the needle I will set this as recommended to the 4th grove, however any advice on fuel settings would be appreciated. I have printed off the info. that I found on this site, although the settings are from guys riding in much warmer climates. Any info. here would also be Gratefully received.

And finally, does removing the AIS emissions system make a big difference and where would you get a kit from or is it a case of filling the holes that are left after removal with rubber bungs?

Any advice on the above would be much appreciated.

Have an 04 WR450 struggle to handle the power it has already , my main problem is electric start issues, which are really getting me down.

Removing the ais makes it a lot easier to jet and stops it from poping on decel

i ordered it from the TT store fits like a glove and the JDjetting kit

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