Jump to content
Sign in to follow this  

07 crf250r jetting ASAP

Recommended Posts

Ok i have a 2007 crf250r and i got a fmf factory 4.1 with a megabomb header and i just put in a high compression piston and did a little polish and porting and i also have a boysen quickshot on my carb well i still got that bog right at the crack of the throttle and like if i roll the throttle on its fine but when i just snap it to be aggressive on the track it either almost dies or does die!Im in desperate need of some jetting help!thanks guys:worthy:

Share this post


Link to post
Share on other sites

i tried that and it didn't work...from what i hear i need to play with the AP(accelerator pump) timing!u think i should change the leak jet...stock is 55...i have my main jet at 175 and my pilot to a 45!any suggestions?thanks

Share this post


Link to post
Share on other sites

Your getting to much fuel Try a half a turn.It should be a 42 pilot 45 is too much.Theres a thread in the jetting sticky on how to determine the right size pilot.

Share this post


Link to post
Share on other sites

kk ill drop my pilot...is my main jet to big then?and the AP mod wouldn't have any affect cuz the AP screw always stays with the AP lever when u twist the throttle wide open!well atleast i don't think it would work!

Share this post


Link to post
Share on other sites
Your getting to much fuel Try a half a turn.It should be a 42 pilot 45 is too much.Theres a thread in the jetting sticky on how to determine the right size pilot.

If the pilot was too big, it would sound like you forgot to shut off the choke, when throttle is rolled easy and steady on, that's where the pilot is noticeable. The second you crack the throttle wide open, you can feed it all the fuel in the world (almost:) ) The bog comes from lean mixture, that's why the AP is there, and the timing is so discussed.

Share this post


Link to post
Share on other sites

This worked for me

Jetting Specs:

172 Main

42 Pilot

45 Leak

1 1/2 Turns out at 66 Degrees, 55% Humidity, Elevation @200-300 feet

2 Turns out at 77 Degrees, 85% Humidity, Elevation @ 200-300 feet

Stock Needle

Carb Float Baffle Removed

Backfire Screen Removed with Twin Air Filter

(Still had low end bog coming out of corners)

Bog Fix:

This is pretty time consuming and labor intensive but worth the time, it works.

I had adjusted my AP squirt to just miss the carb slide, not good enough on the 07. The AP timing is the key to getting rid of the off idle bog and needs to be adjusted with the bike running.

I removed the seat, sub-frame, mid pipe & mufflers, air box and rear shock...to get to the Accelerator Pump linkage. I re-installed the airbox, and exhaust (with minimal bolts) just to crank the engine. The engine was still hot from riding a previous moto. With the engine running I turned the AP timing screw IN at 1/4 turn increments, then snapped the throttle to check for the bog. The bog was gone at 2 1/4 turns IN (clockwise) from my original starting point. Turning the screw IN delays the pump squirt, so the fuel is missing the slide by a pretty long way now. After getting it to feel pretty good on the stand I put it back together and took it to the track. Major difference in throttle response and all the low end bog is gone and no bogging off big jumps.

Share this post


Link to post
Share on other sites

Is the float bowl baffle the shingy meat plate thing in the bottom of the float bowl?it has two screws but it looks to me like it is has two lil tack welds!is it ok to just pop it off?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×