07 Crf 250

i thinking about purchasing a 250f in about a month or so after coming off a 250 two smoker. i rode a kawi 250f 2 years ago in B class and felt better on it than the two stroke. Im pretty set on getting a honda. i have been riding since i was 4, and racing since i was 10. This year im moving to A class and want a bike that will treat me good.

i was wondering what mods people have made to their crfs that had made the most noticeable change for the money spent. And what can i do to avoid some early problems that the crfs may have right from the factory. Also i dont know if i should grab an 07 now and try and get a cheap deal, or wait for an 08?

any feedback would be alot of help


ive heard putting an 05 carb (37mm) on the 06/07 helps with the bog

yea, Dirt Rider said the '07 has really temperamental carb, and they put an '05 carb on jetted to '05 settings, and it worked like its supposed to.

other than that the bikes runs good. if you're going to A you probably already know the benefits of suspension revalves. but that's what I'd do first, get the susp. revalved

Only problem with puttin the '05 carb on, is itll run ya over $1,000, the AP mod is free and cures the same problem, then you still got the benefits of the bigger carb.

sweet thanks !!

Wow! 05 carb over 1k? Are you crazy.... You can get a used 05 37mm carb on ebay for 250 if you are patient, maybe even cheaper.

My 06 has no bog. It was, however, a local pro's stock class race bike, and I'm not sure exactly what they did to it.

The real reason the four stroke is so much more critical to carb. settings than a two stroke is, the four stroke does not have a fuel sump/reservoir, the crankcase of a two stroke holds a substantial volume of air/fuel. This excess volume of air/fuel charge, masks over intermittent lean conditions.

The four stroke on the other hand has no such reservoir, each individual intake cycle provides every bit of air/fuel for the next power cycle.

This is the reason intermittent lean moments are so noticeable (bog). Excessively lean air/fuel ratios will not ignite with a conventional spark plug design.

The CRF carbs have at least three different design flaws, each one is more than capable of inducing the lean condition previously mentioned. Hard landings, negative G's and fast throttle input, just to mention a few, are more than enough to expose the short comings of the current CRF carb design.

The R&D Power Bowl, is designed to address all the problem areas of the

CRF carb. The adjustable leak jet is a popular feature, but it is only a convince for ease of tuning. The real improvements are built into the

bowl and pump cavity. It is designed to purge out the air pocket that build

up in the pump chamber, the air pocket dampens the effect of the diaphragm,

causing a lag in throttle response.

For more details on the design, click the link below.


i like the idea of the R&D power bowl because it will address all the probs of the carb and not jus the bog from quick throttle response. Do you know of anywhere with more info on that product? Ic that it is used by factory KTM and other big names so should be reliable. Thanks!

Hey R1Dean how does your adjustable leak jet work, I have one but never got instructions on how it works. I have left it the way i got from you but would like to know what direction to turn it to go larger or smaller. Thanks

The rule of thumb with the screw is: 2 turns out =#60, 1 3/4=#50,

1 1/2t=#40, 1 1/4t=30 ect.

Hope that is helpful.

Thanks Dean

Only problem with puttin the '05 carb on, is itll run ya over $1,000, the AP mod is free and cures the same problem, then you still got the benefits of the bigger carb.

That is not true.....Tokyo Mod has a 05 Carb with mods for $600!

and if youre lucky, you could find one on ebay!

i run a lot of single track on my 06 crf250r and it has no bog..... it will bog if u have been putting for like 20min at like a 5mph then crack it will bog...then rocket off lol

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