Solution to bog when wicking throttle out of turns

I may have found a solution to one of the dreaded bog problems with the CRF250R. The particular bog I’m speaking of is the one some of you may get when quickly opening the throttle at the apex of turns (not landing from jumps). My bike always seemed to kind of “load up” and bog at that point. So, here is what I did and learned.

1st. I’ve always adjusted the AP timing screw setting so the fuel squirt just missed the back of the slide when you wicked the throttle open on the stand (engine not running, sub frame removed). However, the bike still didn’t run super crisp. This past week I ended up taking the side cover off the carb so I could access the AP timing screw while out riding the bike. I started messing with the screw adjustment in ¼ turn increments and then took a lap on a simple track with no big jumps. I slowly turned the screw in which slows down when the pump is actuated on the 2005 37mm carb. When I got about a ½ turn in (slower) from the “bench” adjustment mark the bike started to pull cleanly out of turns. I ended up moving in another 1/8 of a turn and bingo the bike started to pull with no hesitation when wicking the throttle. The rear wheel also felt more connect to the ground and the throttle – if that makes sense. I then move the adjustment ¼ turn in the other direction and the bog was back! So, from this experience I learned just how critical and sensitive that adjustment is. And, setting it on the bench like I’ve always done just doesn’t cut it. You need to dial it in out on the track with the bike under a load. So, if you’ve got a similar bog problem it may be this same issue (as long as the rest of your jetting is spot on). Give it a try…

You are right on the money. Further 'adjustment' is achieved with the leak jet. Sounds to me like you are a perfect candidate for an adjustable leak jet like the one Merge sells (TT store carries it.)

I have one of the R&D power pump ALJ's on the bike now :busted:

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