08 CRF250R Athena Big Bore Jetting.
Posted: Thu Apr 09, 2015 1:50 am
Hi All,
I have recently purchased a 08 CRF250R second hand and put an Athena 280 Big Bore kit and replaced the intake valves and springs with Pro-x stainless units. I didn't get the valve seals recut I just blued them up to check the contact area and it looked good so I lapped them in. It fired up straight away and rides pretty sweet now.
I have been looking into the jetting for this set up as I have heard these bike run pretty rich from the factory.
This is how I found the carb settings;
Pilot: #42
Needle: NMTS, 3rd from the top
Main: 188
I did some fine tuning and this is how it is now;
Pilot: #40
Needle: NMTS, 3rd from the top
Main 188
Mixture screw: 1 3/4 out
Does this sound about right? The more I research this the more confused I get as there seems to be a few different stock set ups depending on where in the world you live.
Cheers
I have recently purchased a 08 CRF250R second hand and put an Athena 280 Big Bore kit and replaced the intake valves and springs with Pro-x stainless units. I didn't get the valve seals recut I just blued them up to check the contact area and it looked good so I lapped them in. It fired up straight away and rides pretty sweet now.
I have been looking into the jetting for this set up as I have heard these bike run pretty rich from the factory.
This is how I found the carb settings;
Pilot: #42
Needle: NMTS, 3rd from the top
Main: 188
I did some fine tuning and this is how it is now;
Pilot: #40
Needle: NMTS, 3rd from the top
Main 188
Mixture screw: 1 3/4 out
Does this sound about right? The more I research this the more confused I get as there seems to be a few different stock set ups depending on where in the world you live.
Cheers