[MC4]

Hi, I had an 2006 CRF 250X that I jet with the JD kit, Red needle, 158/42, AP mode, open air box and an Arrow muffler and it was a very nice bike, with lot of low and middle power, not very high rpm but it was ok for technical and slow trails that was I do.

Right now I sold the "old" 2006 and bought a new 2011 (2009) 250X and tried to jet it myself, because I spent all my money on the bike and it's a "little" expensive to buy a new JD kit from the States (I live in Portugal, you know).

So, I opened the airbox, maybe a little too much, because I didn't remember what I have done 5 years ago, so I opened all the upper section of the box (I don't know if this is a problem of too much air) and as I have an NCYS needle and saw that many guys use it, I put this needle in, clip 4, and as this 2009 bike has already the 42 slow jet I only change the stock 132 main jet with a 155 one and the pilot screw passed from 1 3/4 out to 2 1/4 out. No AP mode required in this new 2009 bike, I have an Arrow header that has a little larger diameter than stock and use a new Leovince X3 muffler and didn't do the pink wire and I ride sea level to 2000 ft.

Right now what I state: the bike revs very high, it never ends with a very linear, not explosive power and even in 5th gear the bike cuts the ignition off at more than 12.000 rpm (I have an rpm meter) but it has no soul as my old 2006. At low and middle power it's difficult to get the front wheel of the ground.

This is the contrary of what I want, I don't need to do very high rpm but need low power to raise the front to pass roots, rocks and so.

I read in some forum (didn't remember which) that this new 2009 motor has a different top head more like the 250R and maybe because of that I can't find the low end as I expected, but as also the carburetor isn't the same of the old bike, now it's a FCR14B and the stock needle now is the NKKT maybe the NCYS needle and the 2 1/4 out isn't the correct jetting for this 2009 CRF 250X.

Any advice on this matter?

Thanks in advance from this side of the Atlantic.
Best regards.

Miguel Cunha

[crfsonly]

the larger diameter header is likely the issue. go back to the stock header and see how that feels. jetting isn't going to move the power around.

ken

[MC4]

the larger diameter header is likely the issue. go back to the stock header and see how that feels. jetting isn't going to move the power around.

ken

Yes, I'll try that, but the difference of diammeter is little, so I don't think that this is the issue.
Other guys told me that the new top header and the cam are different from the 2006 model and more like the R model, so maybe it's not possible to get the "old" bottom end power.

Regards.

[crfsonly]

the X head change was in 2007 and is the same head for the '09 X. the X has always been built to provide more bottom/mid then top end. the exhaust can move the power around and a larger header diameter will cause low end power to drop off. also, the jd kit on the 250x does help with over all power and off idle performance. most are pleasantly surprised at the difference this jetting makes.

[MC4]

..., the jd kit on the 250x does help with over all power and off idle performance. most are pleasantly surprised at the difference this jetting makes.

Yes I understand that, but as the money is short and I have several main jets from my old JD kit and this 2009 model don't need the AP mode nor the change of the pilot jet, the only thing I need is a needle, so I tried to save that money of a new JD kit and try the Honda NCYS needle, as it's easy to get it here in Portugal.

Compared with other 250X from two friends, both 2006 bikes and with the same NCYS - 155/42 setup, their bikes have more bottom power than mine, so I thought that the motor is the difference and maybe the NCYS needle wasn't the right needle for this 2009 250X, but maybe nobody has tried this.

Thanks for your help.
Regards

[crfsonly]

i'd swap back to the stock header/muffler and see how it runs. also, check our jetting database for the 250X and see what others are running with success who don't use the JD kit:

http://www.crfsonly.com/forum/viewtopic.php?t=13472

ken

[MC4]

i'd swap back to the stock header/muffler and see how it runs. also, check our jetting database for the 250X and see what others are running with success who don't use the JD kit:

http://www.crfsonly.com/forum/viewtopic.php?t=13472

ken

Hi Ken, Thanks for your input.
I'll try the stock header next weekend, but about your link there are no new bikes on the forum, so can't compare to them .

Regards