Fine Tuning 39fcr Carb???

[HOT-ROD]

IS THERE ANY POINTERS SOMEONE CAN GIVE?

[methyman]

I got this from Curtis Sparks web site under tech help

The FCR carb should be jetted by adjusting the main jet size, 165 seems to work well in many cases. The pilot screw is also crucial to the proper jetting of the FCR. The pilot screw is located on the bottom of the float below just in front of the main jet. It is a fuel screw, so turning it out will richen off idle to about 1/4 throttle and turning it in will lean it up. 3-4 turns seems to be the most common setting.

Almost everyone that installs an FCR on their 400X fires it up in the garage as soon as they have it on. When you do this it will stumble a bit when you instantly go from a low idle to a full throttle. This is normal. It can be adjusted to where it doesn't do it when you ride. Richening the pilot screw will help this problem. What is happening is normal for a four stroke engine. The YZ 400 experienced the same problem, but work excellent when it is being ridden. Ride your bike before you make a judgment on how it should be set.


Good Luck my FCR39 Rips!!!:D