03 Cr250 Jetting at 6000 ft

[Colorado KDX]

My brother just purchased an 03 cr250 and we are looking for
a starting point on jetting. He rides at about 6000 ft. and 40-50 F. temp.
The bike is 100% stock. Thanks for the help.

 

[bedell99]

Hello,

I have my CR250 set up in Denver with following jets.
this is an 02 model and i know your slide is a bit richer. Use the manual to get a good baseline and i would highley recomend and S-8 nozzle. (this is what the main jet screws into)

Main:340-350
Needle: BEY30-76 1st clip.
Slow 27.5
Slide 4.25
AS 1 1/4 to 1 1/2 turn out

Remember this is for an 02 so your's is going to be a little different. Us e the manual, but i would recommend to go leaner. Also try to use straight race gas. As you already know the ethanol in gas reeks havoc on jetting.

Erik
2002 CR250

 

[Colorado KDX]

When you say slide 4.25 is this a new slide. This type of carb is new to me I'm use to dealing with #5,#6 or #7 Slides. Also is this nozzle S-8 leaner?

 

[pro2k]

I bought a jet kit from Tom Morgan racing and, according to them, the '03 only needs a different needle. 6BEY30-74 is the one you want. From the chart included with the jet kit you need to run a 410 (maybe 400) main jet, 3rd clip position on the needle (6Bey30-74), a 30 pilot jet (stock) and 2 1/4 - 2 1/2 turns out on the air screw (stock is 1 1/2)

 

[tomoad]

thats funny my 03 cr with that needle a 74 , is loading up like everyone else's, im going to try the s8 and s7 nozzle.

 

[Faded]

Originally posted by bedell99
Needle: BEY30-76 1st clip.

This needle is quite a bit leaner than the stock needle, especially being ran on the 1st clip. The needle jet, or 'nozzle' has the same effect as the jet needle. I think all these CRs are way rich in the 1/4-3/4 throttle positions based on everyones jetting specs I've been watching. :think:

 

[markdup]

I agree that the 03 is way rich down low. I have had good results with the S8 nozzle, but still a little hesitation way down low. I then went to a 4.25 slide, and everything fell into place. The bike is flying now. I am now just fine tuning with the needle, but the jetting is definitely in the right ballpark for sea level, for me.

Thanks for all the help on this site!

 

[Colorado KDX]

Will a 4.25 slide be ok at 6000 ft. or should I go up one more size(4.5??
03 cr250 100% stock

 

[Faded]

My 02 came with the 4.25 slide. You might want to check to see if you already have it...

Have you had a chance to jet it yet? If so, any problems?

 

[bedell99]

I know for a fact 03's came with a 4.00 slide and 02's came with a 4.25 slide which is a "leaner" slide.

Erik

 

[Colorado KDX]

Thanks for all the great info- my slide is a 4.00 - I'm thinking about trying the 4.25 I hope it will lean it enough. Has anyone used a 4.50?

 

[pro2k]

MARKDUP.....what jetting are you using on your '03? Are you using all the stock settings and the 4.25 slide?

 

[pro2k]

Just called my dealer and the parts guy didn't even know what a slide was!

 

[Ojref]

Originally posted by Colorado KDX
My brother just purchased an 03 cr250 and we are looking for
a starting point on jetting. He rides at about 6000 ft. and 40-50 F. temp.
The bike is 100% stock. Thanks for the help.

That's some major air dude. Tell him to land first and then jet it.

 

[markdup]

Pro2K,
Other than the slide and the s8 nozzle, I am using mostly stock jetting....
35 pilot, 1.5 AS, float set at 15mm, 420 main, 4.25 slide, 3873 needle on 3rd clip. This seems to work really well. I like a smooth transition onto the main jet, so i find the slightly richer clip setting works better. I am currrently experimenting with an old, richer H272 needle i have, which also seems to work well ito smoothing the transition.

 

[mos11b]

Hello,

I have my CR250 set up in Denver with following jets.
this is an 02 model and i know your slide is a bit richer. Use the manual to get a good baseline and i would highley recomend and S-8 nozzle. (this is what the main jet screws into)

Main:340-350
Needle: BEY30-76 1st clip.
Slow 27.5
Slide 4.25
AS 1 1/4 to 1 1/2 turn out

Remember this is for an 02 so your's is going to be a little different. Us e the manual, but i would recommend to go leaner. Also try to use straight race gas. As you already know the ethanol in gas reeks havoc on jetting.

Erik
2002 CR250

Where do you buy your race gas, I live on the north end of Denver in the Longmont area...

Also what grade do you use... I have never ran race gas, in my 20+ years of riding! I know that is strange.. even when I was racing Motocross in the late 80's to mid 90's.

I also live in Weld county, I don't think ethanol is added in Weld county! That is what the gas stations advertise do you know if this is true?

Thanks Mike
:think:

 

[bedell99]

Sorry to tell ya but ethanol is required by law to be run in gasoline during the winter months in colorado. There is a really good place to buy race gas on Union & Sante Fe. It is called Duggins. i would recommend the TT111, it is very similar to VP C-12.

Erik

 

[mos11b]

Sorry to tell ya but ethanol is required by law to be run in gasoline during the winter months in colorado. There is a really good place to buy race gas on Union & Sante Fe. It is called Duggins. i would recommend the TT111, it is very similar to VP C-12.

Erik

I found a VP dealer in Thornton, it is at;

Big T High Performance
2577 E 79 Av
THORNTON, CO 80229 - 6108
(720) 872-2414

They carry just about everything VP sells. The warehouse is protected by a $40K fire protection system to give you an idea.

http://www.vpracingfuels.com:

:yikes: