Fmf 4.1 jeting

[HondaRiderDashit]

I got a crf250r 07 and when im going fast it makes a slight bog, any adjustments you guys know of? im running a 172 main jet.

[William1]

You need to properly set up the AP. Not the main jet, not the needle and not the pilot jet or fuel screw.

Read your owners manual, it explains it all very well.

[92db]

Is this bog when gassing it or when the motor is running at a higher RPM. If it is a bog William1 is pretty much on the money but I wouldn't rule out a fuel screw adjustment either if it is on acceleration.

[William1]

Fuel screw is for idle only. Adjusting it to compensate for a fuel issue off idle is when people end up with all sorts of woes.

As the bike throttle is opened, the pilot jet and fuel screws effect is constantly diminishing and the needles straight diameter is increasing. Once you get to about 1/4 throttle, the effect of the pilot jet and fuel screw is about zero.

[HondaRiderDashit]

If im going fast and let go of the throttle it makes a bog

[William1]

So you say if you are at wide open throttle, you close the throttle, the bike slows down? When does the 'bog' happen? You must be very clear.