CRF150R - Rough Idle /Off Idle Bog - After Pipe and Flywheel Weight

I just bought a brand new 2012 CRF150R for my son who is 12 years old.  I wanted to make the bike a little more trail friendly so I installed a 9oz flywheel weight and FMF Q4 pipe.


Problem now is that the bike does not idle very good and had a terrible off idle bog where much of the time the bike just dies.  Im looking for any solutions you may have as i dont have much experience with this bike.


Thanks for you help!

Try a 40 or 42 pilot jet and get an R&D flexible fuel screw, makes adjustments a breeze as there isn't much room under the carb. Install a merge racing spring on the carb, it got rid of the bog on my bike. If you still have a bog try a 50 leak jet.

Plenty of set-ups in the CRF150 expert forum. Jetting on these motors need to be spot on at the low end circuit. 2012 came with a linked/stronger AP arm/spring. Also check the AP squirt and timing. Depending on elevation a 48-55 leak jet, 40-45 pilot and a 135-140 main. A good option is a QS3 external adjuster for fine tuning. You don't need it but it helps along with the remote fuel screw.

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