From another thread on this forum, if this bloke told me the sun wasn't gunna come up I would go buy batteries.......
I have been porting H-D heads since 1978 {sold biz last year} anyway , I always liked to use 89-90 % valve to seat ratio . The H-D 110" heads have a 93 % ratio on the intake !!!!!!! YOU WANT POWER ,CHEAP ? Put in a 2.125 intake valve { H-D # 18190-08} $15.50 ea. } that will get you a 90.5 % ratio and do a 4 angle seat cut , 'mill' the heads .030-.040 and use a Cometic .030 head gasket and a cam.
let me 'spain' a little. When you have 93% seat to valve {1.930 dia.} with a 2.080 valve ,you need to look HARD to see the 45 degree cut and forget about the 60 degree ! You have nothin but a big hole. Nothing to cut your angles on ,right ? By going with a bigger valve {.045 bigger} you can do a 30-45-60-70 cuts. YES ? THE STOCK VALVES ARE 'BACK CUT' 30 DEGREE. its all about making the Y , with the back cut on the valve and the cuts on the seat. Look at a Y , bigger on the top and then narrows down ,yes. Just remember 1 thing , 80% of your air flow is controlled by the valve and the seat. The only other way is to weld up the ports. The stock 110" heads flow BAD. once you 'fix' the valve and the seat {cuts} they do fine. Whatever ,been doing this stuff for over 30 years,not trying to sell ANYTHING. Dewey