Drilling questions

[vinmansbrew]

I'm not asking about sound or anything like that. What I want to know, is where people drilled with hole saws. Inside the smallest port, which would be about 7/8th in.
Or have people drilled between the 2 round parts?
Reading some of the past topics, it sounded like some people used hole saws larger than 1 inch?

Yes I know, 2 bros, ect. But I am saving for an engine rebuild on a different bike.

 

[Senior]

Drilled mine out (straight down the smallest port) in 2009 ish, still happy with how it sounds to this day. - 65,000 miles since I did it.
From memory I think I used a 22mm , 300mm long drill bit. (looking at the photo I think could have possibly gone a little bigger - like the 7/8th you say)




This is a good comparison on sound of before and after (not my bike though), doesn't really make it much louder, more changes the tone
http://youtu.be/hGLPMVqjzg0

Previous thready from back in the day
https://www.600riders.com/threads/drilling-the-exhaust.47424/post-518193