04 WR 450 mod tips

Just a few hundred Questions?

Whats the deal with the throttle on the 04 wr450. A freind just got it last week. We took it out to the dairy farm to start the break in, first thing we did was remove that restricting gadget from the pipe, but the throttle doesnt seem to open up all the way. I hear there is something in the carb that needs to be removed? :)

Also what about the pipe. That bithen Ca law "94Decible" :D What are some good pipe options to wake it up and still keep withen a safe sound limit. :D

How about that coolant overflow resevior mounted behind the left rear number plate. Looks like a nightmare. Any potential problems or bad expericances with that?

Any way, if anyone would care to respond with some tips or help would be greatly appreciated.


It has a throttle stop, you need to cut it down. I don't recall the correct length, but any Yam dealer can give it to you out of the service bulletin. You don't want to pull it and toss it as that can cause problems.

I'm running the stock exh. with the cork removed and a GYT-R insert, but there are a couple good quiet silencers availabe...

I haven't had any problems with the coolant res. and haven't heard of any...it's staying on my bike.

You'll want to pull the snorkel out of the top of the airbox and cut the gray wire to the CDI box to enable the YZ-style advance curve. And sort the jetting out, she's jetted for all the corks being in place. Lot's of other things, I'm sure you'll hear about them here :)

Here's a link to a 250f site that describes how to shorten throttle stop. The 450 is similar.


The site also has a lot of other useful info including all the free mods. The '04 jetting comes much richer than the '03 (165 mj vs. 150 mj)but could stand to be richen'ed up just a bit more. As far as sound goes one of the inserts (GYT or PMB) will keep you legal for the least $$$. FMF makes the Q series but I'm holding out to see how the new White Bros E-2 performs when (and if) it comes out.

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