Just bought a New WR450F, can anyone help with a few queries I have.

I would appreciate if some of you could clear up a few queries for me. I read various discussions on how to enhance the restricted bikes from their stock form, as the WR is absolutely flat compared to my ex YZ426.

The quick win I understand is the a YZ throttle stop (5JG-14591-00-00) as well as the exhaust insert (GYT-5TJ93-75-00) which also keeps the noise level within 96dbs

Q1: Can any one tell me if I need to change the jetting if I remove the existing exhaust insert?

Q2: While I wait for the part to arrive, If I remove what looks like the washer on the external end the existing exhaust insert but retain the spark arrestor, will this increase the noise level? I need to keep the noise down as I intend to compete in the local Hare and Hounds and they are not too friendly with loud bikes.

Q3: I have read a lot about the Woodruff Key, has this problem being eliminated with the 2004 models?

Sox, pull the insert out of the exhaust. You should have the Euro WR so you shouldn't have the throttle stop, leave the jetting alone (unless you're at high elevation). The Woodruff key issue is gone. Pull the lid off the airbox.. What do the 04 Euro pipes look like?


I have to disagree with Dan about the jetting. Play with it and find the perfect setting. Look at all the old posts about jetting and find the one that fits your situation (or just ask Indy).

Enjoy your new ride!

I have the USA model, 5TJ5, bought as a 'grey import' as they are called in this country. Retail is about £5300, I got the USA model for £4600 which is cheap for over here. Had to change the motorcross tyres for enduro ones which the dealer kindly swapped. Regarding the throttle stop, the dealer said just to remove it all together (?)

I have the USA model

The USA models come jetted very lean to pass EPA standards, I assume the restricted intake and exhaust are also needed to pass those standards. When I first got my WR450, I felt it was a nice trail bike, just way underpowered, then I did the usual mods(see below), this definitely awoke the beast within, I am very satisfied with the performance now.

Hey There,

I have the Canadian Version and live in Putney. Where do you go riding in Surrey?


New to the South of England and I have not had much luck finding people to ride with. I joined a local enduro club but the members do not seem very active out side their races. I will try and enter a Hare and hounds with various clubs every two weeks if I can.

Happy to meet up to explore the green lanes if you are up for it?


New to the South of England and I have not had much luck finding people to ride with...

Go over to Visordown.com, it's a UK based forum, the link goest to the Supermoto section. There's plenty of good "blokes" on there, who do loads of trail/offroad riding, & I'm sure you'll find plenty of people "darn sarf". I don't post on that forum much anymore, as I sold my SM, but I still keep in touch with one guy who lives in Ilford, Essex. Just remember, being a newbie you'll need to get in a "virtual round" for the boys & they'll treat you right.


BTW, I post as "Jacka$$" over there on occasion.

Hey Sox, the UK version does have a resticted throttle stop if its road registered, but the delaer restricts them at PDI if they are going on the road. So you get the unresticted stop with the bike. However....as yours is a USA version it probly is restricted, you can tell easily by the throttle movement. Resticted, they will move like only a quarter of what ANY other motorbike will. Easiest is to by the YZ unresticted stop but you can cut yours down (to 27mill??).

The UK ones also come with two needles, again a weak horrid thing for DOT regs, which you junk as soon as you take delivery. To be honest, I dont have the old crappy one to tell you the number of, but any Yam dealer that sells these should help you wih the unrestricted needle. (Or get a JD kit off TT!)

As for jetting, once the stop and needle are done, I went up to a 165 main jet, (you may have this as its "std" in the US model I beleive, then I undid the pilot jet screw a whole turn).

I heae the UK models are not restricted thru the CDI via the "grey wire". I have not touched mine, but general concensouns is the US ones are! So you may find disconnecting the the grey wire gives you something.

You may find the US exhaust can is different, remove the insert that may or may not be fitted.

Hope this helps a bit.

Thanks mate, will give it a try.

Regarding the throttle stop, the dealer said just to remove it all together (?)

Dont do this as you will have a problem with the carb slide opening too much, you can always cut the WR throttle stop to 23mm which is close to YZ spec. I most definitly suggest JD needle kit, the performance over the stock needle is a lot better. I would also recommend upgrading from stock exhaust for better performance.

JD needle kit it is then, will order one of these.

Thanks for the tip on not removing the throttle stop completely, I thought the salesman’s advice did not sound too solid. The throttle is definitely restricted as it only has about a 1/4 of a turn.

Regarding the exhaust insert, I removed this and it is in one piece and my previous description about a washer is incorrect. Without the insert the bike is really loud and more like my ex YZ426 . Sounds great to me but I will be kicked out of the enduro events in the UK if I leave it like this.

Anybody know where to can check out the ‘PMB exhaust insert’, tried a web search but nothing coming up. My dealer is going to get back to me on the Yamaha part GYT-5TJ93-75-00.

Regarding the air box, bearing in mind I have the USA model, does the UK model have the intake silencer or snorkel? I will remove this as the first step and see if I need to go further at a later date.

The grey wire: does this only affect the USA model? Does anybody know if the UK model comes without the grey wire restriction to the black box?

Finally, how do you post a digital picture along with the text in this forum?

Just to clarify for me plaese: Does the UK model come with out the grey wire?

Anybody know where to can check out the ‘PMB exhaust insert’, tried a web search but nothing coming up. My dealer is going to get back to me on the Yamaha part GYT-5TJ93-75-00.

Go to Hi-performance exhaust insert , I have one and it's better than any of the "big name" inserts....

if you have USA model then yes there is a grey wire, best location to disconnect it is near the handlebars by the CDI unit, but if you have the Euro model I dont believe it has the grey wire ie.. no need to do the mod.

Pro-moto billet insert is better than stock unit but not much in performance gain.


Also recommend Zip-ty fuel screw, it makes tuning a breeze.


I've owned 3 WR's, I've tried just about every needle, jet, pilot configuration. I have always come back to stock. Feel free do disagree, but for me stock has always been best. :thumbsup:


Since you live in a wet area with lots of water crossings, I assume, you will want to do the breather hose modification to avoid drowning the bike. Use the TT search feature on the subject and get those hoses tee'd off before you go snorkeling with the WR.

And welcome to TT. Wealth of knowledge here. :thumbsup:

I Just want to ask a question. The '04 wr has the battery in the airbox lid correct? If you take the lid off but you still want the battery for the electric starter where are you guys putting the Batt.

We are looking for more power from a brand new WR 450. Do we need to put an exhaust cam in it since they changed it so you couldn't go a notch on the chain to get it to YZ spec?

The things that have been done so far are:

Grey wire

Throttle stop

Exhaust insert

Airbox snorkle

Additional holes drilled in the airbox around the rear of the box and behind the right side cover of the box

JD Jetting kit

Any more help would be appreciated the owner of the bike just switched to Yamaha from a CRF 450 and is fighting for a #1 plate in his class in District 37 Desert racing in So Cal.

Will do the mod tomorrow for the crankcase breather as I have my first Hare and Hounds next weekend and there are plenty of 'puddles' around.

Yeah the forum is absolutely fantastic. I am really impressed with the quality of advice, as well as the feeling you can ask the most serious to the most basis questions and everybody comes back with a positive response.

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