What is Jetting? WR450F

Is there somewhere I can download info on jetting a WR450F?

I have read that changing a starter jet from a 70 to a 72 would make it easier to start. I am only a beginner and know very little about these topics, but when it comes to improving the performance of my bike I am always willing to learn. :thumbsup:

if you don't know what jetting is, it is best left alone. If you are a new WR owner, give yourself some time to learn the starting procedure properly before you make any changes. When I first got my 426 I had starting problems, but with practice I got better and now I can start it first kick every time, even after it's been dropped. Also jetting changes arent something that shouldnt be taken litely if you dont have that 'feel' for an engine that is running rich or lean. I suggest you read this page .

This will al least explain to you how the carby works. It is not WR specific, but aboth the only thing that the WR carby has that isn't mentioned here is the accelerator pump. I believe they fixed the pump on the 450's, but not 100% sure.

Hope this helps


Hey thanks. It's a start. :thumbsup:

you don't say where you live or if your 450 is a '03 or '04. has you bike been modified in any way? the '04 is much closer to being jetted correctly stock. the '03 needs some help. as was said above, if you don't know much about jetting go slow and get as much info as possible before you start. the 450's come with a very good manual. study it. this forum has a great search feature, take advantage it. one thing that has served me well is to look for posts from owners that live in similar areas of the country that i do. many of them will have their jetting specs listed with their posts. by the way, the 72 starter jet is not needed in the summer, stock will be fine.

I live in Newfoundland, Canada where the temperature this time of year ranges from 5 to 20 degrees celcius. My bike is an 04 and it has no modifications. :thumbsup:

What is the altitude there?

My seal level UK 04 has a 45 pilot jet (std) fitted and a 160 main. It runs the richer needle on pos 4, athough I will be moving this to 3 in an attempt cure the part throttle hunting common on the 04.

The altitude here is between 100 & 1000ft. :thumbsup::awww:

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