JD jetting Wr250f

[tone61]

Just wondering what JD jet settings people have settled on. Bike is a 2013 WR250f. Tried recommended 185 main with red needle 4th clip and way too rich. Did oring mod and installed #60 leak jet supplied which has really improved initial throttle response and no bogging. Pilot circuit is ok ( 45 ) but needle and main settings are shit. I’ve heard using red needle 4th clip with stock 170 main is the go. Anyone found the sweet spot combo.

[Nutty]

No mention of the PAJ or MAJ you have fitted...you're wasting your time chasing fuel flow if the airs aren't done/correct. Get onto Thumpertalk, there's a WR jetting archive on there.

[tone61]

Originally Posted by Nutty

No mention of the PAJ or MAJ you have fitted...you're wasting your time chasing fuel flow if the airs aren't done/correct. Get onto Thumpertalk, there's a WR jetting archive on there.

Pretty sure I mentioned I fitted the 185 main and #60 leak as per instructions and the pilot circuit was fine with the standard 45 pilot jet and currently back to 170 main. Yep I’ll try Thumper talk and hopefully get the info I need.

[Nutty]

Originally Posted by tone61

Pretty sure I mentioned I fitted the 185 main and #60 leak as per instructions and the pilot circuit was fine with the standard 45 pilot jet and currently back to 170 main. Yep I’ll try Thumper talk and hopefully get the info I need.

The main (MJ), pilot (PJ) and leak (LJ) are all fuel jets. Your symptoms sound like incorrect air jetting (MAJ/PAJ). The fuel jetting swings off the air jetting.

JD kits are designed for US spec low RON/high MON fuels. I'd suggest using a OBEPQ or a OBELQ genuine YZ-F needle. I prefer the P if running YZ-F cam timing. Get yourself a Boyesen or R&D adjustable LJ as well. After a while you'll work out why...

Best air fuel sets are PJ45, PAJ 90 or PJ42, PAJ85
and. MJ170, MAJ185

There's 13 adjustments on a FCR, get them all correct and it will blow a FI bikes doors off.