Jump to content
Sign in to follow this  

Between jump bog...07 CRF250

Recommended Posts

So my jetting has been great since you diagnosed my last problem burned...Now my next is killing me. When landing hard off a jump, the bike will bog quickly, then wake up. i'm getting slight pops when decellerating, and the bike rides GREAT any other time. should i look into the white brother's "carb kit" ?

my jetting as it stands

main 162

pilot 40

leak 45

1 1/2 turns out on the fuel screw. about 3k feet above sea level, and 100 unleaded.

thanks eddie!

Share this post


Link to post
Share on other sites

I ve seen in the magazine "Motocross Action", a jetting thing which makes the CRF250 bog gone for good, its not expensive, gave it a 5 out of 5.:censored::ride:

Share this post


Link to post
Share on other sites
I ve seen in the magazine "Motocross Action", a jetting thing which makes the CRF250 bog gone for good, its not expensive, gave it a 5 out of 5.:applause: :applause:

What is it?

Share this post


Link to post
Share on other sites

I have the 2006 CRF250 have exact same problem

a predictably "baaw" on big flat landings.

Bike has the full AP mod. Thin part of the diapragh rivet 2.5mm.

160-165 main. 42-45 pilot (depends on temp wher you live). Would love to hear from someone that has installed

a carb sleeve. The Bike barks off idle runs awesome but

that damned landing bog. I am almost certain 40mm carb

is the culprit. JD jetting kit and the whitebros kit will

be the next step i think before I throw it

Share this post


Link to post
Share on other sites

I been having the same problem and I broke down and ordered a 05 Carb from Tokyo Mod. I will see this weekend if solves the problem. I had the 05 TM on my X before I sold it and it work great with zero bog. You may give TM a call and they my be able to help.

Share this post


Link to post
Share on other sites

PC racing Carb vent system to prevent vapour lock.

Float bounce limiter. Those are the two option

I will look at. Both makes sense. Carb vents drawn upwards to the airbox means fuel wont sit in the "bend".

When landing hard off jumps the float can force its

way into the fuel inside the float bowl thus opening

the valve and letting in more fuel=flooding

Share this post


Link to post
Share on other sites

Well got the TM 05 Carb and put it on my Crf250R 07....I just I a thought it cured....the bog and made the throttle so responsive that it felt like different bike. So if looks like the 07 carb is going on ebay.

Share this post


Link to post
Share on other sites

With respect to the White Brothers kit, Tim Olson at Motocross.com did a review of it and said it totally eliminates the bog. There is a video review at the site - look under "features".

Share this post


Link to post
Share on other sites

MXA says the dreaded bog is due to Honda going to a bigger carb in 06 and sticking with it in 07. Honda partially addressed the problem on the 07 bike but it is still there to a lesser degree. The solution is to replace your carb for an 05 model and apparently the bog will be completely gone. The alternative is to get the kit you mentioned. It looks like a little sleeve that slips inside the carb and reduces the inside diameter.

You could try going to http://www.motocrossactionmag.com and searching the archives. You might find the article i'm talking about.

Good luck..

Share this post


Link to post
Share on other sites
lower the float level. Should solve the problem.

Traditional logic does not appear to work on

the 40mm carb when installed on a CRF250.

I have a 165 main 45 pilot. removed the steel baffle

plate from the bowl and allowed more fuel in the bowl

by bending the float valve needle tab so it shuts off

later than standard setting. I have done AP mod with

wire and ground rivet. I can now land hard if I keep

the bike straight but if I land "whipped" it bogs.

05 carb or White bros sleeve. All threads seem to

end there........

Share this post


Link to post
Share on other sites
Well got the TM 05 Carb and put it on my Crf250R 07....I just I a thought it cured....the bog and made the throttle so responsive that it felt like different bike. So if looks like the 07 carb is going on ebay.

What did the Tokyo carb cost?. Oem is like $600:eek: :bonk:

At least there is an answer out there.

The 40 mm should be a sought after commodity for

larger displacement bikes so money hopefully can

be recouped...

Share this post


Link to post
Share on other sites
What did the Tokyo carb cost?. Oem is like $600:eek: :bonk:

At least there is an answer out there.

The 40 mm should be a sought after commodity for

larger displacement bikes so money hopefully can

be recouped...

Well it was just under $600, we got a sponsorship discount and since we have gotten 2-3 carbs done buy them in the past. The reason why I went this route istead of the insert was I like the addtional mods they do to the carb to make the throttle very crisp and easier on the starting (prob jetting and spring). I also like having the support that comes with the service to be able to talk to these guys on the phone on tunning jetting. If you have the money or you want the added support and service (Crisp throttle/Jetting) and dont want to mess with carb inserts go with Tokyo Mods 05 Carb. However if you are on a budget get the WB insert, IMO it sounds that both cure the bog.

I do have the 07 Carb that has the Tokyo Mods included that has a slight bog when repeatly whacked (woods riding) that I think I am going to get the WB inset to compare the differents when I get some time.

Share this post


Link to post
Share on other sites

I spent some time playing with the ap timing screw.

fully backed off with no gap is not an option.

a few half turns in I got good squirt from the nozzle..

I checked to make sure the black arm and screw

where still touching on full throttle.

I then ran two laps of safety wire to eliminate any

slack when the throttle is opened quickly.

Result is very good response. I can not get

bog on idle when sitting on the stand. I had a couple

of minor bogs on landing when not in the right gear

But thats probably to be expected. The main

thing is the predicatable landing bog is almost

eliminated with a whole new level of confidence

on big jumps.

I still believe if you are on a tight jumpfilled track

fit a sleeve or 05 carb. Cross country of open mx track

the added top end of the 40mm is welcome.

Thats it i am happy to go riding.....:thumbsup:

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  

×