194 replies to this topic

[mojomx TT Newbie]

I just bought an 04 250R (CA model).  It is stock except for a WB silencer.  The bike runs perfect and I believe it has the stock jetting.  I am a little worried reading that the bike comes lean from the factory which will make it run hotter.  My manual is on the way so what are the stock jet numbers for my bike?  Any suggestions if I should richen it up.  I just don't want to screw it up because because it is really screaming right now.
Also, if I remove the spark arrestor screen will that change anything?

[mag TT Bronze Member]

05 250X
05 R Cam
05 R exhaust
Pink wire removed
Airbox cut to line
JD Red 4th clip
40 PJ
55 LJ
172 Main
1.25 Turns Fuel Screw
1200'
50-70


I tried 42PJ but had to turn fuel screw in to 1/4 turn out.

[evhfan2003 TT Member]

My Honda dealer told me the 55 leak jet was the stock size.  Was he correct for a 49 state bike?

[MDWright TT Newbie]

Several people were talking about changing the Leak Jet to a 55.  That is the stock one on the 49 state model.  Doesn't the leak jet work with the accellerator pump?  It seems that the low end bog (mine and my brothers - both stock, minus exhaust baffle, both have the bog) is a lean situation when the throttle is pinned.  Would it help if the accellerator pump pumped more fuel, maybe by using a larger Leak Jet, say around the mid 60 area work?  Or does the leak jet have little effect.  I am in Illinois, 60 -90 degrees F, 500-1000 ft.  Also, it is extremely hard to start when cold, will the larger #42 slow jet help this, as well as the bog.
Without other mods, what is the best, and easiest fix for these problems?
'04 CRF250X, '03 YZF-R6

[fact4 TT Newbie]

When You Cut the Pink wire ( or move it to the proper location) It only Raises the rev limiter 1000 RPM, The power cure stays the same.  

[DougJ TT Silver Member]

MDWright said:

Several people were talking about changing the Leak Jet to a 55.  That is the stock one on the 49 state model.  Doesn't the leak jet work with the accellerator pump?  It seems that the low end bog (mine and my brothers - both stock, minus exhaust baffle, both have the bog) is a lean situation when the throttle is pinned.  Would it help if the accellerator pump pumped more fuel, maybe by using a larger Leak Jet, say around the mid 60 area work?  Or does the leak jet have little effect.  I am in Illinois, 60 -90 degrees F, 500-1000 ft.  Also, it is extremely hard to start when cold, will the larger #42 slow jet help this, as well as the bog.
Without other mods, what is the best, and easiest fix for these problems?
'04 CRF250X, '03 YZF-R6

The 55 leak is stock in the 49 state bikes, with the leaner 65 leak stock in the CA bikes. The larger # leak jet is LEANER. Think of it this way: The accellerator pump provides a set squirt of fuel, the leak jet allows some of that fuel pass back into the float bowl, the smaller the leak, the more fuel squirted into the intake tract.
I went from the 40 to 42 pilot on mine right away and it was quite a bit better. I ride from around 1000' to 5000' most of the time. I just put in a 55 leak tonight and made some other changes to go with the FMF Q pipe I got of e-bay, hopefully I can get out this weekend to see how it works.

Doug

[intmid8tr3 TT Newbie]

what does moving the pink wire do?  havent got my bike yet
steve

[REDCHIP TT Member]

Doug, let me know how the changes work out. I have a 55 leak jet on order and am considering putting in a 42 pilot jet at the same time.

[MDWright TT Newbie]

Thanks for the explination.  Do you know if you can get a smaller leak jet maybe around a 45 -50?  I still have a very nasty bog when snapping the throttle.  I changed the pilot to a 42 and adjusted the screw from 2 to 3 turns out, and it still falls on its face for a moment when the throttle is pinned, then takes off.  Any ideas?
Thanks
Michael

[DougJ TT Silver Member]

intmid8tr3 said:

what does moving the pink wire do?  havent got my bike yet
steve

Pink wire mod ups the rev limiter, some say it's also a different ignition curve also, but I have found nothing to confirm nor deny that. I don't like the idea for the X. If you're a revver and do ALL the CC mods I could see it, but it's not what I want.

Doug

[DougJ TT Silver Member]

REDCHIP said:

Doug, let me know how the changes work out. I have a 55 leak jet on order and am considering putting in a 42 pilot jet at the same time.

Prior to the FMF Q I had a 42 pilot, stock needle on #3 (from top) and a 140 main. I have the airbox opened just in the area that was covered by the rubber snorkel thingy and the end of the exhaust diffuser was cut off. With no changes other than going to a 145 main after switching to the FMF Q the bike was lean. This was at around 2500 to 3500 feet and maybe 65 70 degrees.

I put in the 55 leak, 155 main and a JD blue needle that I borrowed in the middle position. There was a noticeable difference during fast throttle openings but it fell on it's face immediately thereafter, and it's never done that before. I put the stock needle back in at position #5 and WOW does it feel good! I'm testing at my property which is around 1300 feet. You shouldn't snap the throttle open on a 4 stroke without expecting it to bog... But while testing I was able to do just that from a normal idle, 2nd gear and it just barked and pulled away strong! I'm going riding tomorrow and maybe Sunday so we'll see what it can really do.

So here's where I'm at: 55 leak, 42 pilot, screw as required (about 1 3/8 now), stock CA needle (NCYR?) at 5 from top, and a 155 main.

Doug

[DougJ TT Silver Member]

MDWright said:

Thanks for the explination.  Do you know if you can get a smaller leak jet maybe around a 45 -50?  I still have a very nasty bog when snapping the throttle.  I changed the pilot to a 42 and adjusted the screw from 2 to 3 turns out, and it still falls on its face for a moment when the throttle is pinned, then takes off.  Any ideas?
Thanks
Michael

I would think you can get a smaller # leak jet, but I haven't looked into it. You may not be able to get it from Honda, so you can check with Sudco or some other shops.   Check it out. I have heard of guys blocking the leak jet completely, but that sounds kinda drastic to me. If you're just snapping the throttle open then that's all that's wrong. Think roll open and not snap open... I solved that once for someone as they went from two stoke back to 4 stroke by raising the idle slighty and remiding them not to snap it open from low revs...

Doug

[REDCHIP TT Member]

Thanks for the reply. What you're running now is is what I'm planning on trying.

[DougJ TT Silver Member]

UPDATE.

Took the bike out Friday to a place in the National Forest near my home at around 3000' to 3500' and about 65 degrees. I then went to Clear Creek on Sunday. The bottom and power is so much better it's hard to tell what kind of improvement I have on top!  

I'm VERY happy with the way the bike is running.

Uphill in second with the RPM down so low that about all I can hear is chain slap, crack the throttle and up comes the front wheel.

There is one hill at Clear Creek that I'm pretty familiar with. I've climbed it a bunch of times, and Sunday I used it as a Vert Dirt Dyno... The approach to this hill is rough and previously I could make the approach in second, click into third right at the base and carry that maybe 100' up the face before going back to second to finish the hill. Yesterday I did the same thing, except I left it third at fairly low RPM's and even had to roll off because I was carrying to much speed at the top! Big difference. I did it several times, even intentionally starting out with the RPM low and it blasted right up. Great low end for this little bike! It pulls cleanly through the midrange and all the way to rev limiter without a hitch.

Doug

[moto949 TT Bronze Member]

i installed those recommended procircuit specs, rips off the bottom, way lean on top. i am going to leave the bottom alone and set the top back to stock for now. 2005 crf250r

[CO_Thump TT Member]

i was surfing somehwhere and found this list of yahama oem jets for their keihin fcr implementation in the yzf's & wrf's...

i have the boyesen ap cover w/ a 55 leak & i still have bog, but it's better than before.  i'd like to try a smaller leak jet to see if i get even more improvement.

i can't confirm that these are correct or not, but the part numbering scheme looks legit.  i *would* be interested in any online venues that i could order some of these from...

hope this helps..

Yamaha OEM Part Numbers

YZF/WRF Leak Jet: 4JT-1494F-XX-00 (for all model years)

#130 XX = 33
#120 XX = 31
#110 XX = 29
#100 XX = 27
#90 XX = 23
#80 XX = 19
#70 XX = 15
#60 XX = 11
#50 XX = 07
#40 XX = 03
#35 XX = 01

[French canadian TT Newbie]

I everyboy, i m screwed with my settings...250x 04

I ride in Québec Canada at 0 to 2500 feets, I open the intake and the exhaust (air box open, remove screen filter and cut the cup and spark arrester )

I have also put a 42 pilot and a 135 main, 5 clip from the top (2 from bottom) for the needle, I still got hesitation on throttle...( like stock one), temperature here is 55 to 80 all the summer (15 Celsius to 28Celsius).

WHAT SHOULD I DO, if someguy have the same elevation and temperature and really good settings please HELP ME... i don t want to have problem whit that cause the season is beginning....

[dstroud TT Newbie]

I need a couple of things cleared up for me.  When you guys say "fuel screw"  Do you me the pilot screw??  Does anyone mess with the air screw that is under the airbox boot??  I had my bike jetted great, until I installed the smog block-off kit.  Now, I have a nasty bog right when I open the throttle.  Normally on a two stroke I would adjust the air screw.  What should I start with?  Thanks for the help in advance

-145 main
-Needle jet that Honda recommends (16204-MEN-671) 4 from top
-stock leak
-2 3/4 pilot screw

Dave

[CRFrider8 TT Newbie]

i need some jet settings for the 250R so can someone supply some please?

[money_pit TT Bronze Member]

I think I'm finally there!

I may play with clip position, but 4th seemed too rich, but that was with the 155 main so I may try again, again feedback would be appreciated
'04 X

0-1000ft
50-100 F
42 PJ 1-3/4 - 2
NCYS third
165 Main

Airbox Cut, Twin air Filter and Cage, bf screen removed obviously
Dr. D Full exhaust
Pink Wire Stock

Again, any feedback on needle position or type would be appreciated, I wouldn't mind trying on eof those funky blue or red needles you guys have been using, but until anyone has one for sale, I'll stick with the '04 R model(I think) for now!