04 WR250 Jetting

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DYsLeXIC
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04 WR250 Jetting

Post by DYsLeXIC »

I'm new to all this and have a jetting issue - she sputters a bit @ 1/2 to full throttle - I'm taking to the dealer to have them fix it, but I'll learn on my own and have read alot at Thumpers' and here....I read the MXNut issue, but I'm just going from stock.....someone told me too that it's too rich from the factory....you'd think the dealer would know about our altitude and jet it appropriately...anyhow....anyone have my bike and advice on setting for Mcleans and Waiprous on warm dry days??

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dirtyboy
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Post by dirtyboy »

I've found that jetting a 4 stroke for temperature and Calgary to higher elevations makes very little difference. I used the same jetting at 20 above as 5 below with no issue.

I have had an '03 and an '05 but it has never been stock. I run the YZ cam and therefore lean towards the YZ jetting.

I'm sure rooster will have some ideas, but I'd say start with the main jet. The main will control from 1/2 to full throttle positions (not RPMs). Get a nice hill to test on that you can run wide open throttle. Test it. Change the jet one size smaller. Test it. It will either be better, the same or worse. If it is better decide if you should try one more smaller. Otherwise go larger.

The main jet can be changed with a 17mm wrench and a 6mm socket without any trouble. Remove the bottom plug with the 17 wrench and remove the jet with the socket. It takes a minute or two to do it. If you go out with a couple jets, you'll have it dialled in in 30 - 60 minutes.

My guess is that your jet should be between a 172 or 178. :cheers:

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