Cv slide

vic at the bottom of the page these a link to CV performance check it out ken run's that show as well

A 7/64 bit is about the closest you an get in a fractional drill bit, unless you have access to metric size bits. The actual hole size in the slide is approximately 2.6mm but the machining process generally leaves them smaller or partially blocked. A 7/64 bit is 2.78mm. As a reference a 1/8" bit is 3.18mm, but since most use a hand held drill the resulting hole can often end up in the 3.25mm range or larger.

A slide with too large of a hole can act like a shock that has lost it's dampening. The hole acts to regulate how fast the air above the slide can be displaced as the vacuum changes and draws the slide upward. The same applies as the slide attempts to return to a closed position, and just like a shock if it is allowed to move too quickly you end up with a slide that bounces and hunts for the proper position.

If the hole has been drilled larger than 1/8" I suggest either replacing the slide or modifying the slide by way of filling and redrilling. Since I've always been sort of a cheap guy I can't see throwing away a slide and dropping $40-50 on a new one. I've had success repairing over-drilled slides by doing the following.
1) Fill the over drilled vacuum hole with JB Weld. Hi-temp silicone will also work.
2) Drill a new 7/64 hole adjacent to the old hole.
This method will salvage a perfectly good slide from the garbage and keep a few $$ in your pocket.

I should also mention that cutting the slide spring (another weak attempt at performance) is never recommended. Cutting the spring shortens it's travel but has an adverse effect on returning the slide to it's original position. If you want better throttle response use either a SE race spring from a 44mm carb or the CV Performance slide spring which has been designed with the correct length and tension. When used with the vacuum hole at stock or 7/64 you will have the correct balance of tension, travel, and slide response.