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Jetting Recommendations - CRF250X

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First of all, I can't seem to debug this horrible off-idle-bog that this bike is known for having right out of the factory. I've performed the CCC mods, except for changing the cam. Here's the setup as of today as far as jetting. BTW, the off-idle bog never really seems to get better - only worse when I change (if changed). Oh, and I have a CA 250X - not sure how much of a difference because the carb for the CA has a whole different part # then the carb from the 49-state. I know for sure the needle in mine is a stock CA model needle - NCYS

pilot - 42

main - 152 (Honda recommendation)

leak jet - 55 (played around between 55 and 70 - 70 makes it even worse)

needle - NCYU 3rd from top

pilot screw (fuel screw) - stock position

airbox - open

exhaust - Dr. D 250X exhaust

CA smog pump - removed (don't believe it'd make that much of a difference)

I ride occasionally in temperatures ranging from 60 - 75 degrees F. Ride in Lucerne Valley, elevation of approx. 2000-2500 ft. I'm trying to at least get the bike working right down here at sea level before changing it for up there. Any suggestions Mr. James Dean? All are greatly appreciated!

P.S. - I asked for a JD Jetting Kit for X-mas! Might this GREATLY improve my complications? I sure hope it will!

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Dan, below is a copy of a post I just made on another thread;

The needle taper is all wrong on these original equipment applications. What you are experiancing is some combo of;

Engine not totally warmed up,

too rich at idle to get the combustion chamber hot enough to burn the fuel from the accelerator pump,

Too lean after it gets off the pilot on to the shank of the needle.

Some will say your need to shorten the suirt duration on the accelerator pump. Myself I prefer not to modify that on 250s, open class bikes yes.

Go for the JD kit! It will do wonders for the bike and save you lots of time & trouble.

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I ride Johnson Valley in Lucerne also. Only bike mod is air box cut. Air pump and pipe are all STOCK. Lucerne is a little higher, I figure 3,000 foot elevation and it has worked well on this bike and on my old 2-strokes. Mine runs a little lean down here but runs great up there (no hesitation).

250X jetting:

Pilot = 42

Main = 155

Blue JD Needle on 4th position from top

Fuel Screw at 1 3/4 turns out

Everything else in carb is stock.

If you are running a pipe you might need to go richer on the needle and fuel screw.

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Have you tried going richer on the needle? Moving the clip down to the 5th position from the top did wonders for the bog on my wife's bike.

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I have tested the richest setting to no change whatsoever. It may not be as horrible a bog, but it still didn't fully cure it. Even at this setting the bike will still die if I crank the throttle fast enough - I've also played around with the AP setting. I guess I should wait and see about this JD jetting kit before I really start messing around with the carb... thanks though!

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The short term solution is to run a richer needle clip position and turn the fuel screw outwards. I won't entirely solve the problem, but will help. Keep the idle speed up.

Make sure the accelerator pump is squirting if the problem seems excessive. You may need to remove the subframe (swing it upwards) and look into the carb to observe the squirt. You might want to have a #55 leak jet ready if you decide to go that far (from a CRF450R).

Thanks,

James

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I've actually already installed the 55 leak... in fact that's all i've been having sucesss (if any) with. Thanks again... I tried richening the needle, but it really didn't seem to improve at all. I will try adjusting the fuel screw and playing around with the needle position, keep ya'll posted...

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Well, after carefully re-checking the intake for any signs of an AP squrt, I've found that the AP hasn't been working all this time. I'll probably take it apart today, clean it all out, and stick it back in. Keep ya posted...

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Well, after carefully re-checking the intake for any signs of an AP squrt, I've found that the AP hasn't been working all this time. I'll probably take it apart today, clean it all out, and stick it back in. Keep ya posted...

Any news yet?

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Well, like I said the AP wasn't squirting. We fixed that and put the bike back together. It has definately improved, although the bog was still easily noticable. However, this time once I gave it a quick crank the bike hesitated, then screamed to the moon. Going in the right direction.

I also received a JD Jetting Kit for Christmas. After putting on Christmas night, I decided to test it yesterday. I set the jetting as he recommends in the instructions for a sea level to 3000ft rider. Main is 158, Needle is Red 5th position, Pilot is a 42, fuel screw is at 2 1/4 turns out, leak at 55. Bog is back, just as bad as before. Now it sounds like it's a rich bog, at least in the way that the bike dies. I'm going to try a 70 leak jet (going both extremes) and see how that fixes it. Keep ya posted...

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Still bogs, horribly. I'm not sure which direction to go now. I have the JD kit, but it almost seems like since I've stuck it in there, it just got worst. I'll still be trying out a couple more leak jet settings... For now I'm going back to the stock leak jet and stock AP depressor setting. Let you know what I find worked best from today.

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Dan

Did you try the 45 Pilot with the 55 leak and JD kit?

Which way did you move the depresser screw ?

Our 250X is almost there. Junior went out and did some hot laps even with temps in the high 25s+ yesterday. There was no bog, actually a tad of rich blubbering when going to full throttle. The 158 may be a tad rich with race fuel, even at low temps. He almost looped out a few times over some logs as the bike responded so well.

Good luck and keep us posted.

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"..... Main is 158, Needle is Red 5th position, Pilot is a 42, fuel screw is at 2 1/4 turns out, leak at 55. Bog is back, just as bad as before......"

Try running the fuel screw further inwards with the #42 PJ. Set it near 1 1/2 to 1 3/4 turns out and keep a slightly faster idle speed. The bike needs to be fully hot and an idle speed per spec.

(The 2 1/4 turns was intended for a stock #40PJ)

Is this with baffle in or out?

Are you sure your expectations are realistic? Make sure you ride the bike to get it hot before testing for a bogging condition. Does it bog under normal riding situations? Riding conditions is where the testing is needed.

Thanks,

James

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Well basically I hear that many are able to almost get the bog away completely. The reason I know somethings gotta be wrong is because I compare the bog to that of my father's 450 - which is almost none. I'm sure I can get it closer to that than it is right now. If I could, I would host a website and stick a recording of the sound (and maybe video) of the bike. Thanks for letting me know. I turned the AP depressor screw about 1 turn out, and 1 turn in from stock position (had a green marker where stock was). Both ways it seemed to bog just the same. Last week I had a 152 main jet, and the NCYS needle in the richest setting - I was going the right direction as the bog wasn't as bad (the bike would stumble but recover and rev to the moon!). After installing the JD jetting kit, the bog came back again just like when I first performed the CCC mods, however now it seems like a rich condition because after I flick the throttle and the bike dies (yes it dies when flicked fast enough), I'll go to start the bike and usually a nice little puff of smoke will come out - never was there before.

The bike bogs under normal conditions - always has, even when it was new. I didn't notice it much until I did the CCC mods, and even after that I didn't notice it much. Only time I noticed it was when I would mess around (jumping, wheelying, trialing 😢 ). I'd go to flick the throttle for the front wheel and there'd be a horrible bog with a delay - most of the time I would let off and the bike would recover. I don't ever recall it stalling much at all, as I would let off instantly. My friend recently bought a 250X and his does the same as my did when it was new.

One question, might the jetting be a little different as this is a CA model? I noticed that when you look for a part number from Honda, there are two different part numbers for carbs - 1 for the 49-state, and 1 for the CA model apparently.

If the weather lets up I will try doing as you state. Do you recommend that I start over with the stock CA carb's #65 leak jet? I may just try it as I'm running out of ideas. I realize this bikes are very sensitive to small adjustments, so I will try one thing at a time. Thanks for all your help.

Bodyman, what exactly is your altitude with this jetting? I'm about 100ft above sea level in CA. However, I ride in Lucerne Valley, CA, and the elevations there are about 2500-3000ft I believe. I realize that tuning down here isn't best for what's up there, but as long as I can get it working down here, I feel that I may be able to jet it appropriately for up there. Thanks again everyone! Wish me luck in making this thing work!

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I also forgot to mention that this is with a Dr.D exhaust - didn't come with any instructions for rejetting for use with it.

Today I fired it up and let it warm up for quite a while. After it was quite warm, I began to test it. Still bogs pretty bad - wants to die. The temp isn't much cooler than 65F, don't know if this has any affect. All I know is that it's still not working. Will try other setups soon. Didn't touch anything except the pilot screw - which is at 1 1/4 turns out.

I also have another jetting question. As this is a CA model with different carb settings than the 49-state do i need to swap the stock 65 leak jet for a stock 49-state #55 leak jet? Also, is the air smog pump a factor? Should I leave it in with your recommended settings or take it out? What about the exhaust, does it need to be opened up?stock? I have a Dr.D like i stated and I'm not sure how big of an affect it would have.Thanks!

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I am at 500 above sea level. We rode at 1400 this weekend.

Jetting can be bothersome, I am unsure of the CA model changes.

I talked to a tuner today that is intouch with factory teams and races a CRF250 himself. He mentioned that jetting is a bugger. He said with the X model to open the Air box, use the R needle and a 165 - 170 main. He said the main helps the bog some when you wick it open. He goes way up on the main until the bike starts to blubber and stop pulling like the choke is on, then backs up one size. He also said the bikes are race bikes and the design wants you to get them hot to run properly, the 04 model more than the 05 as the 05 cam and head is less prone to bogging.. Jetting becomes easier as you ride it harder. I guess you can tweek it for trail riding with enough time as most have done here.

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75% SUCESS... I let the bike warm up a LONG time, and finally after wicking the throttle a couple times it began eliminating the bog. I'm going to put the jetting back to how JD recommends and leave it there until I go riding this weekend. Thanks for ALL your help!

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