jetting

[ellandoh]

2003 cr250 jetting help needed
800 ft average 75 deg. average
fmf fatty w/ turbinecore 2
vforce3

bought it and the guy who owned it rejetted w/ what mxa recommended for stock which was not even close for the bolt-ons.
apparently there was a lean condition down low stock but that is untrue w said bolt-ons.

anyone w/similar configuration pleasae help I can probably adjust for elevation or temp myself thanx

L+O

 

[cjmx]

this may help

http://www.fmfracing.com/jetting_center.aspx

 

[ellandoh]

fmf

fmf copied mxa, not well either they left out the part about larger cutaway on the slide which is nice if i want to leave breadcrumbs to find my way back to the truck.....and by breadcrumbs i mean spooge on the trees :think:

 

[tony91]

What kind of gas are you using?

 

[ellandoh]

premium

94 octane

 

[SoCalMatt]

I've got the same mods on my 02 CR250 and am in the same boat as far as jetting goes. I bought the bike used and am not sure what jetting is in it but all i know is that it is running lean. I'm spewing oil all over at 50:1. I just bought the S8 nozzle online and can't wait to install it and see how that works out. I'll let you know, I should get it over the weekend. If you read more threads on this topic you'll find that everyone is saying to switch to the Keihn PWK carb. However others have had good results by switching to the S8 nozzle and changing the main and pilot jets. What jetting, its hard to tell, there are so many posts. I'm gonna try the FMF settings with the S8 nozzle and we'll see how it goes.

What are the stock jetting settings anyways? Anyone know?

 

[ellandoh]

02 settings are different than 03 but i have them for you tho
sj-----32.5
mj---380
as------1.5
needle-6bey30-74
pos----2nd

stock sea level-1000ft
60-80 degrees
reply and i will give you hondas recommended corrections fo alt and temp which are probably off but ill look em up for ya

 

[SoCalMatt]

Thanks, I would really like the recommended changes from Honda. I just bought the service manual online as well but of course that isn't here yet either. guess i'll be spewing and coughing like usual for tomorrows ride.

I normally ride at about 3000ft in the desert and temps right now are getting into the 80's here in socal. Thanks! :cool:

Does anyone know what jetting should be used with the S8 nozzle?

 

[ellandoh]

I normally ride at about 3000ft in the desert and temps right now are getting into the 80's here in socal. Thanks!
2 turns
32.5
2nd position
360
6bey31-75

2500-5000ft
60-80 degrees
nozzles arent in book period

 

[SoCalMatt]

Thanks, I'll try those settings with the S8 nozzle and see how it goes. I'll keep you posted, hopefully I'll get the nozzle by Sunday.

 

[cjmx]

here is what I run in Denver at 5280ft

slow 30
BEY30-76 needle 2nd clip
slide 4.25
S8 nozzle
340-350 main
Air screw 1 1/2 turns out
40:1 91 octane
v-force 2
fmf fatty pipe
stock silencer

spark plug reads fine and no spooge at all

 

[pro2k]

where can I get that slide and s8 nozzle? I ask my local dealer and he looked like a deer in headlights so I just said nevermind......

Anybody come up with good jetting around 900-1000ft, 68deg?

 

[sandflyz]

Sorry to horn in on the thread but here goes. I bought a 03 cr250 and it still has the stock jets in it. It comes jetted for sea level and i live at about 4000'. Anyway, I went one size leaner on the main jet, and am wondering now what effect this will have on my airscrew settings?

 

[SoCalMatt]

You can get the S8 nozzle from bikebandit.com. Their part number is 39104-001 and it is from a 1996 YZ125. Look under OEM parts and you can even look at the schematics of the carb or any other part for any bike that you want for that matter. its a great site. I just got mine yesterday and will put it in today and see how it goes.

 

[NO HAND]

where can I get that slide and s8 nozzle? I ask my local dealer and he looked like a deer in headlights so I just said nevermind......

Anybody come up with good jetting around 900-1000ft, 68deg?

You have to go to a yamaha dealer, I ordered mine in the optional carb parts list for the yz125 1998. I have heard people say that it alot cheaper if you buy it at carbparts or sudco, not sure which.

 

[SoCalMatt]

I installed the S8 nozzle and it didnt seem to have too much affect overall. It seems a llittle more responsive but I was only able to get it into second gear, for a brief moment, in my townhome complex yesterday evening so havent given it the true test yet. I took my carb completely out, cracked it open, checked all the air holes for clogs and cleaned it up. What a pain in the ass to get back in, hahaha. I did notice it has a 390 main in it, so I bet that has been my biggest problem. It also has a 32.5 pilot jet. Im going to get a 380 and a 360 main and pop them in and then I'll report back on how they worked out. :cool:

 

[SoCalMatt]

Is 3 months too late to report how it went, :laugh: Sorry, I have been working on remodeling projects at the house and havent ridden too many times. :coocoo:

Well I just raised the clip and put in a 380 main so we'll see how that goes. It seemed to make a difference but I only rode it on my street. I also bought a 30 sj that I might try, all depends on how this setup goes after taking it to the desert this weekend, then I can really test it. The Honda manual says to use a 350 main for my temp and altitude but I think I will slowly get there one jet at a time, hehe. This is never going to end, can these bikes really run and sound crisp????

Anybody else make any changes on their 02 CR250's lately?

My current settings:
S8 Nozzle
380 main
32.5 pilot
1st on needle
1 1/2 to 2 turns on the Air Screw

 

[SoCalMatt]

I'm also running 91 octane pump gas at 50:1, its been 90-100 degrees and I ride at 3000 feet. :cool:

 

[ellandoh]

got my 03 perfect!!!! :)






went ot the dunes .............new ball of wax :bang: went in the carb 5 times on the trial run day , 1 or 2 more trips in their over the 4th and ill have my yearly dune excursion jetting sorted :nod:

 

[SoCalMatt]

Nice, so what did you end up with and how did that compare to what the Honda manual recommended?

 

[ellandoh]

been 80-90deg avg 1000'


ended w/ .............................recommend
410 mj ............................ 420mj
30 pilot ............................ 32.5 pilot
6bhy38-74 2nd..................... 6bhy38-73 2nd
1 1/4 to 2 as ......................1 1/2 as

 

[SoCalMatt]

Is that 6bhy38-74 needle leaner than the 73. I dont know my needle #'s but Im assuming the 74 is the diameter thus making it richer? You never tried the S8 huh?

 

[SoCalMatt]

I mean leaner, oopsy :laugh:

 

[ellandoh]

74 is leaner im not positive if it has a longer straight section,diameter, or less aggressive taper but in the manual it was the next leaner in the direction of higher altitude corrections or warmer temps so i went with it and it has become so snappy down low with the settings im on for the track i almost cant get used to it :coocoo:

oh i got vf3 and fmf fatty tc2 silencer


the low end is also like a ....................... [insert analogy here] anyone who says cr s have bad low end hasnt jetted, im pulling some 4s out of corners , and doubles right out of corners are now a breeze when i used to watch the 4s gettin it

a gear high now has the pull to get into the meat



well thats enough you get the pic
:laugh: :laugh: :laugh: :laugh:

 

[SoCalMatt]

Im glad to hear that you have it dialed in, it's very reassuring to me. I am not giving up and finally feel that I am on the right track. Now that I am starting to understand the whole jetting process I should be dialed in soon. Thanks for your help! :cool: