Boring out a stock 400ex carb

[waytooslow]

I want to bore out my stock carbs on my 400ex because I have heard a few poeple say it really helps but I am not quite sure what the specs are that they need to be bored to? Is it a straight bore or a taper bore? How many mm should I bore it to? I have some CNC equipment that I can use and I am a machinist by trade so I thought I would give it a try. Any info would be appreciated.

[cals400ex]

i believe that when you send it in to sparks or rocky ridge, they may do one or two more things than just bore it out. however, the stock carb is a 35.5mm. it can be bored up to 38mm. good luck

I don't think it's put on a machine to be done. A dremel tool, a careful Eye and practice on previous carbs is how it's done. I have a bored stock carb and yes it does help but I'm willing to bet a dremel tool is what is used to do the job..:cool: