HELP??? Jetting

I have an 04 WR 450. I can't seem to get the jetting right. I have changed several jets and can't seem to get the right combo :) My local dealer is worthless and i have turned to the experts on TT. I live in wyoming, so I will constantly ride between 6000 and probably about 9000 ft. I live at 6200 and do most of the riding around there. I have got several suggestions from TT, but I notice they are riding in much lower elevations. Right now I am running a 158 main jet, 45 pilot, 65 starter, and a 60 leak jet. Every ride, my spark plug is white :) Please help,, thank you all.

Anyone have any suggestions?

I'm at 5000 ft and the overall rule of thumb for here is lean the needle one step and go two sizes lean on the main jet. This will get you in the ballpark. The assumption is the bike is correctly jetted for sea level. Several people mentioned that this bike is jetted lean. If your plug is white, that indicates a lean condition. I assume that because of the altitude that you (or intend to) "uncork" the bike or use a less restrictive exhaust. This will also lean the bike. All this leaning may make the bike ok at your altitude since higher altitudes make a bike run richer. On my previous WR250 03, just doing the free mods and popping the insert leaned it enough that I did not have to re-jet.

Unlike the WR250 my WR450 stock leak jet is good as this bike does not hesitate off idle. The stock needle on the 05 is non adjustable. You can order the 04 needle. There is a JD kit that a lot of people rave about that you can order if you are not comfortable with jetting.

I'd also wait until it warms up, if you do it yourself. You can end up chasing your tail if you jet while the temperature changes. 40's and 50's require different jetting than 80's or 90's. When it gets 70's, that is when I am going to try to dial in the bike.

I am in Albuquerque and ride the same elevations. The bike actually ran pretty good in stock form with a 165Main jet. I had heard so much about the JD jetting kit, I bought one to have avail before my bike was delivered. I put in the JD kit anyway and currently run a 165 main, 45 pilot, red needle on clip position 4, 50 leak jet, and I don't recall the starter jet but left it stock. Runs great at 5000 up to 10000 although I do get the infamous bog with a full twist off idle. I have the stock baffle removed and an GYTR insert, pulled the air box snorkle, trimmed the throttle stop. All seems good. Try the main jet change and let us know if that does it for you.


For the infamous bog, check the 250 forum and 250F FAQ on leak jets and accelerator pumps. The accelerator pump only works when you crack the throttle. If your jetting is correct and it still bogs off bottom, the accelerator pump needs to squirt more gas. Unfortunately, the new 05 manual deleted all the info on leak jets, accelerator pump, and jetting your bike.

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