[marko_]

It was said like this "Open BTDC 42 degrees" in here: http://www.aperaceparts.com/tech/05 gsxr1000.html

What does this mean?
Is it that point where intake valve starts to open or is it the point where intake valve is open for how much?

 

[RoadManiac]

come on man that last part doesnt even makes sence.... its first thing you said
youre valve opens at 42 degrees before top dead center

 

[boosted 92-1100]

It it is the point where the intake valve starts to open in degrees hence the term BTDC.