Bike: 2006 YZ250F 50th Anniversary Edition.
Mods: Handguards. Plastics, graphics, and tires are in the mail.
Issue: Bogging

I bought the bike a couple months ago.  It was brand spanking new. Maybe 5 hrs on it, if that.  I rode it in my neighborhood a bit, but not on the track/trails.  Still havent ridden it properly(waiting on new tires and graphics).

I did some searching, but cant find an exact answer for my area. The bike has quite a bit of bog down low.  I want to get rid of it, but dont exactly know what to do.

I read that a #40 leak jet would help and the o ring mod.  But does that work for all areas and elevations?

Im riding in the Sacramento Valley, so its pretty much sea level.

Thanks

Try the fuel screw 1st if this is not good do some of the mods on here. I ride at sea level with no bog having said that if I let the revs drop too much and turn the throttle too quick i.e not being smooth I do get a hicup. I see this as my rider error more than a bike bogging issue.

MM

Do the oring mod and leak jet. Check the AP timing, set if incorrect. Fuel screw is for idle only.

William1 said:

Idle or closed throttle William? I have had some sucess adjusting the fuel screw as it affects the transition on opening the throttle.An example of this could be a back firing bike on decel if its too lean. Adjust the fuel screw a bit richer and back fire is gone and the bike is smoother on the throttle transition. This is not at idle just closed or very small throttle openings. If its not adjusted right people tend to snap the throttle and get a hesitation.

The amount of fuel varied by the fuel screw is such a tiny amount it rarely has any noticeable effect unless..... the bog is related to a lean condition between just off of idle and just under 1/4 throttle due to the needle straight diameter being on the thin side. So the correct fix (if this is the case) would be to up a letter (towards "A") on the needle. If it were a lean condition, this would also be fairly apparent at steady state throttle in this range under load (4th~5th gear) as a 'dry' sounding bog (engine firing but dry sounding) Vs. the typical AP bog the is purely 'flat' (sounds like the kill switch was hit).

Ok I've never had a bog like the kill switch just a slight hicup if I'm not smooth. The bog you are talking about like a dead engine does it re start or do they stall?

MM

The bog I have is slight, but I still want to fix it.
When a grab a handful suddenly it stutters.....
But when I roll the throttle evenly its fine.

Thats the issue that I have....

Ahh mine does that at low RPM I always saw it as me being a bit slack. Let us know if you fix it al together with the mods. I can't ride mine atm otherwise I'd have play based on the info here.

MM

MartyMOOSE said:

so popping on decel in second gear could be a lean needle jet? i can usually get rid of it with the air screw, but maybe a richer needle is the right way? sorry for the hijack:busted:

Popping on decel can be lean pilot and or air screw adjustment. They compliment each other. It could also be an air leak in your exhaust joints.
MM

I had bog off idle to about 1/2 throttle.  It was too rich.  Installing a fuel screw did fix my problem now I can pop wheelies make the tail get loose and all. Before it did not get up and rip till it got u p and running.  Before it did not pop any, now when setting up for turns I get slight 1 -2 pops sometimes and the exaust note is chrisp.  I know that william says its only for idle but I cant explain why it fixed mine?

Dirtsky said:

Some fuel screws (the alloy ones) make the idle circuit excessively rich, like the equivelent of going up 3 to 4 pilot jet sizes. This could explain it. Or.... you bike was on the ragged edge of being too lean on the idle circuit, the new screw is now adjusted right and you are no longer on the edge of being tragically lean. Bottom line is your bog is gone. My only concern is others may think this is the end all cure. It is for some, not for most. I ass-u-me everyone has thier carb jetted right. They have taken the time to test, set and verify it is correct. This must be done before fine adjustment of the AP is done.