Jump to content
Sign in to follow this  

CR125 and 250 Jetting Thread,...

Recommended Posts

We have been needing a jetting thread for both the 125 and 250 for a very long time, would be a great help for anyone who needs a baseline setting for there year, location, altitude etc. I know nearly everyone has had jetting issues with there CR's and most have even swapped out carbs to something different. I have had 3 CR's and all needed some jetting help. I would love to see this stay on topic and get sticky'd, I will start with my 05, its not dead on but pretty close, going up one size to a 37.5 pilot on the stock carb...


05 CR125

Wiseco Piston/stock bore

FMF Fatty w/FMF Shorty

Boysen intake and reeds

Moose Dual foam air filter

Stock Carb

32:1 Klotz Techniplate full synthetic/ air screw 2 turns out

35 pilot jet/37.5 on the way/currently a little lean on idle circuit

420 main jet/crisp and snappy, pulls hard all the way to WOT

Needle Clip 3 position down from top.

20 Feet above sealevel here in NC

Edited by Dirt Racer

Share this post

Link to post
Share on other sites

98 cr250

Wiseco stock bore

Vforce3 reeds

Stock carb

Fmf gnarly/TurbineCore2

58 Pilot

175 main

Stock needle 3rd clip

Sea level Oregon coast

1.5 turns out


This is what I like, its rich but I can run a NGK br8ev racing plug forever. Crispy and powerful without worrying about not getting enough oil.

Edited by guitarromantic

Share this post

Link to post
Share on other sites

I've done quite a lot of jetting with my 2005 CR144.  Currently running a yz pwk with TPS connected, VForce3 reeds, DEP 144 pipe, 100LL with Amsoil Dominator 32:1.    Near sea level in tropical climate.  My best setting do date is:


Needle: A685/294R, 4th clip.  (optional 2000 CR250 oem)

Pilot: 42

Main: 178

Air Screw: 2 turns

#6 Slide


I have very good settings with JD's Alternate Red, and N3CG/N3CF as well.  I get cleaner settings with #7 slide, but compromise "off idle hesitation" with aggressive throttle snap from idle, and low bog.  I get great results with a 5.5 slide (oem 99 CR250) but compromise 1/8 to 1/4 throttle response, no "off idle hesitation"/low bog.  With the A685, I get it all with no compromise, and I can adjust between trail or track riding with a simple airscrew adjustment.  Slightly spoogy.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this