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Crazy jetting problem!!!

1014 Views 6 Replies 5 Participants Last post by  sumo bill
This is driving me crazy!!!!!!!!!!!!!

As some of you know, I installed a 30mm Kehin PD Carb on my CRF230 replacing the stock 26mm PD

It has a 40 pilot, 1.75 turns out on the fuel screw, 37D slide, 85A needle, and a 158 main.

Engine has a 11:1 piston, BBR Cam, BBR Pipe and some mild head porting.

When running the bike at WOT, and then rolling off the throttle (not chopping the throttle) the engine momentarily cuts out, and then recovers.

Not a huge issue when in the dirt, but when mid corner racing SM, it could really ruin my day....can you say highside!!!!!!!!!!!!!!!!
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It has a 40 pilot, 1.75 turns out on the fuel screw, 37D slide, 85A needle, and a 135 main now.

Holy smokes she rips. I went up to a 138 just for kicks, but the hickup started to rear it's ugly head....ever so slightly. She really pulls up top now. It's a good thing I ordered the rev box...I need it!!

What was screwing me up was the fact that with the OEM carb and the "power up needle" (C30f) you could run as fat of a main as you wanted....because the needle has almost no taper at the end. You really don't get anywhere near the main jet with it.

The 85A needle in the 30mm carb has a much more aggressive taper to it...so you actually get to use the main jet to it's full potontial.
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