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Looking for a baseline for a YZ290F

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I have been having a jetting nightmare with my current Dynojet setup.

I have been reading and doing searchs and I am getting confused.

I just ordered a JD kit and it's on its way here now. I'm looking to get some input on a baseline for a good starting point to work with once that gets here.

2002 Yamaha yz250f

My current set up is:

290 piston kit

Stage 2 Hot cams

Power now valve

K&n filter

Yoshimura pipe

Stock fuel mixture screw

800 foot elevation 85 degrees 60% humidity

looking for suggestions on:

Main size (JD Jets)

JD needle position (and which needle)

Pilot Jet Size

Leak jet size

turns out on the screw

I know full well no one can tune a bike over the web, but I am looking for a good place to start here.

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My 290 BB ran great with a 60 leak jet and all other jets were left stock. In the heat of the summer I go down 1 size on the main jet.

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I feel your pain HDTONY. I ran the same set up on my 02. It ran perfect with no changes to the jetting. I live in a mild climate. Now I have put the same set up in my 07 and have had nothing but problems. I have popping on deceleration and the damb thing does not start hot. (its not the valve setting), the only thing I haven't played with is the jetting. I am thinking there is too much fuel getting in to the cylinder and flooding the plug (plug was black). I am buying some jets this week end and going though the "test and fail"motions of jetting. I am starting with one size lower on the main and working from there. I will reply if I get any where with my night mare

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have 07 wr290f ported head stage1 hot cams 42 pilot 50 leak 175 main red needle middle clip small oring 1 turn on fuel screw runs great

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@ days ago I finished doing a complete valve adjustment, they were in spec but on the tight side of the spec. I have also pulled out the dynojet needle and jets and switched to a JD kit. I put in a 165 main 4o pilot, 1 3/4 turns out on the screw and the large oring for the oring mod. Flat spot is GONE and it fires on first kick now.

I did stall it once on purpose after heating it up and to see if it would restart hot and it did, but we will see this weekend in the woods how it does in real world situations.

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