Rich bog or low power?

When I'm coming out of a tight 1st gear corner and giving it WOT it seems like the power doesnt pick up until i reach the mid rpm range. Do you think it's bogging from being too rich or do you think i'm lacking low end power? My current jetting is 165 main, 48 pilot, fuel screw 1 7/8 turns out, stock leak jet, and stock needle and position. I think im running into a rich bog but im looking for others' opinions.

Thanks, bill804

When I'm coming out of a tight 1st gear corner and giving it WOT it seems like the power doesnt pick up until i reach the mid rpm range. Do you think it's bogging from being too rich or do you think i'm lacking low end power? My current jetting is 165 main, 48 pilot, fuel screw 1 7/8 turns out, stock leak jet, and stock needle and position. I think im running into a rich bog but im looking for others' opinions.

Thanks, bill804

Don't know if I can help but what bike and mods?

08 YZ450f. Engine, intake, and exhaust are all stock.

I have had good results going with a smaller leak jet, try a #40 or #45 if that doesn't help then try adjusting the needle leaner(lower) or better yet get the JD jetting needles

if the bog is when you whack open the throttle then a different leak jet and/or Ap timing mods can help cure it. Such as adjusting the AP timing screw and doing the o-ring mod

I worked on many YZ450's and have never had to do a leak jet swap. When ever I get a bike in and they are complaining of the same thing I first verify their jetting specs. If their jetting is right where I want it to be then I take the bike to the field and adjust the A.P. timing and it cures the bog. I also refuse to wire the A.P. timing because a well tuned A.P. does not need the o-ring mod. I know all similar bikes are the same but different so I would try adjusting the A.P. timing.

When I'm coming out of a tight 1st gear corner and giving it WOT it seems like the power doesnt pick up until i reach the mid rpm range. Do you think it's bogging from being too rich or do you think i'm lacking low end power? My current jetting is 165 main, 48 pilot, fuel screw 1 7/8 turns out, stock leak jet, and stock needle and position. I think im running into a rich bog but im looking for others' opinions.

Thanks, bill804

How hot and or humid was the ambient temps when you were experiencing the bog ? Does it do the same in cooler temps ? If so, you may need a leaner pilot jet change. My '07 uses a #45 stock, but I like a #48 better. I generally don't ride in the hot temps, but I do most of my riding in much clooler temps. Maybe try a #45 for the hotter days, and that will probably sharpen up the low end throttle response.

PS, if you are feeling a very abrupt hard bog, you might have some dirt in the carb bowl momentarilary cloging the pilot

I had a 163 main lying around so i put that in and set the fuel screw to 1 3/4 turns out. If im not happy with how it runs I'll throw the 45 pilot in and a 160 main if im still not happy. Sound good?

your current jettings sounds liek it should be very close, if it's just a bog when hit whack the throttle then it's likely an AP timing issue not a jet issue, I had to turn my ap timing screw about .75 turns CCW

Your know you have the right pilot/fuel screw setting when you get on the throttle good, then let off, you want to a hear a few decel "pops" 2-4 is good, anymore and your too lean, any less and your probly too rich.

Usually on my main I just keep going leaner until I go too far, and run the one thats 1 size bigger, but I have a 165 main in mine right now, it screams up top and I ride supermoto with it so I spend alot of time WFO

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