Can anyone tell me the right way to tune your carbs after installing a boost bottle on a 2001 xc 800. Do you get the idle down first by the idle screw, or the fuel screw? I have 2 sets of instructions stating 2 different ways of tuning. Right now its running o.k. but i know it can be better!

Get the idle down with the idle screw first. Then take it for a rip and adjust the air screw from 1/2 turn to 3 turns where every you get the best throttle response leave it there. That how I did my 98 xc 600.

wait, where is the air screw? i know the idle screw is on top of the carbs right? that big one??

The idle screw is the big one on top, and the fuel screws are the slotted T-type on the right side.( looking down from the seat). What I have done is bring the idle down with the fuel screws. Thats what I read, now Iwant to do it the right way. Do I reverse what I did, then take it down with the idle screw? Do you turn the fuel screws in all the way , then turn them 1/2 to 3 turns for best throttle response?

Also what are my chances of leaning this engine out too much? The main jets Im running are 450s

what elevation and at what temp do you ride I have a 2001 factory race manual and can let you know what to run as mains.

Now remeber that them t shaped screws control fuel flow and not air flow. Thus the more you turn them out the richer you will run. From my experience the newer domestic twins (Liberty Motors) run better with the fuel screws turned out about 1/8 to 1/4 turn past factory setting. I am sure these setting will vary from area to area. As far as the boost bottle is concerned I would not spend the money on one myself when you can get the same gains from just some carb settings. The boost bottle is basicaly a lazy way to fix what can be done with fuel screw adjustments and needle adjustments etc.

XC600, I ride in Northern Ontario. What the elevation would be Idon't know, but temps usually range from -15 to 0. If you could help me out that would be great.