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Please help 2007 crf250r lean bog

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Ok so the bike runs very well and it has the dreaded lean 07 bog. All jets are stock and I heard you should run a 40 leak jet in it but I can't find any leak jets anywhere. Could this problem be fixed with changing the main jet. Any advice would be greatly appreciated!!

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Have you ever serviced the accelerator pump diaphragm?

Not 100% familiar with them yet but there is also some timing/duration adjustments under the throttle cable cover.

No, main jet size only comes into play beyond 3/4 throttle.

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Found this in another discussion, posted by TT member Chuck.

 

How to fix AP: http://crfsonly.com/howto/ap-mod/professor-redbeard450-ap-mod-how-to-guide.php

Fixing dreaded bog: http://www.instructables.com/id/Fixing-the-dreaded-lean-bog-on-Keihin-FCR-MX-carbu/?ALLSTEPS

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Perhaps other members can add their experiences, I've not done much tuning on FCR carbs.

 

Simply cleaned and refurbished, the stock settings don't bog at all when accelerating on my '08 CRF250X,

the only changes I've done is an aftermarket extended fuel screw and slightly increasing the main jet 2 sizes (added holes to the enclosed X airbox).

 

I tweeked the pump shot timing on a friend's '07 CRF250R pretty much by accident

checking out what that screw did (relationship of pump shot versus height of throttle slide)

the engine responded much better so we left it alone after that, not experimenting with other settings.

Edited by mlatour

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A 40-50 leak jet and oring mod will do the trick. Also, a lean pilot can contribute to the bog, so watch this to make sure you have your fuel screw/pilot set up properly:

 

 

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