05 cr125 jetting

[steve_o78]

Does anyone have any jetting experience for a 05-07 cr 125, we changed the main to a 410 and the pilot to a 45 the needle is stk at pos. 3. She still seems a little off, the throttle response is not very good compared to my yz125.the only things that are on it are vforce 3 reed cage and a pc shorty silencer everything else is stock. we are in northwest indiana and about sea level running Sunoco 260 GT Plus, here are the specs

Specific Gravity
0.747
Antiknock Index (R+M)/2
104
RON, Research Octane
109
MON, Motor Octane
99
Reid Vapor Pressure
6.6
Distillation, ○F
Initial Boiling Point
111
10% Evaporation
151

50% Evaporation
219
90% Evaporation
228
Final Boiling Point
254
Unleaded
Color-Light Blue

Oxygen, Wt%
4.8%
Dielectric Constant
17.6

 

[trickin30]

I also own a 2005 CR125. It has the V-Force reeds, FMF Fatty with a shorty silencer, and a Power Now. I also did a rebuild job using a Wiseco piston. It soon started to foul plugs and the bottom end response was terrible. No matter what jets I used the response was terrible and it fouled several plugs :bang: . I ordered OEM parts for a top-end noting that I was using Cylinder A. When I pulled the cylinder off and checked my RC valves they were extremely carbonized. I decarbonized using carb cleaner and Easy off oven cleaner. I also washed the cylinder with Chemtool to break up the carbon deposits on the exhaust side.I then cleaned it in a sinkfull of hot soapy water using a green Scotch Brite making sure to rinse it well and dry it with a towel. I then oiled it lightly with WD40 to make sure the water was displaced. I reassembled everything as per the manual using 2 stroke oil for the piston and moly grease on the RC Valve. I also replaced the 2 dowels on the cylinder head and the bottom of the cylinder where it meets the crankcase. When I fired it up it started on the 4 kick and ran better than it did when it was new!!!!! :laugh: It idled great and cleaned out with a few twists of the throttle. The power is awesome!! :ride: I used the 50 pilot and the 410 main with the stock needle in the 3rd groove and the air screw 1 and 3/4 turns out. The owners manual covers this except for the cleaning tips. Hope this help!!!!