Honda Twins Founding Member
No advice, just info
'75 CB200T, '71 CB450 K4 Half-Breed, '72 CL350 (Sold), '81 CM200T, '72 C70M
and a little red Chineeze scooter
The best answer to the question in your title is:
ONLY YOUR MACHINIST KNOWS - Unless you own a Bore Gauge and have the skills to read it.
Let them tell you how much has to be removed.
Again like already said - Unless you are going for Max Size... but REALLY... These motors are already pretty much as tricked out for performance as needed for Street purposes.
If you really need that much Speed/Performance you should be looking at a bigger bike.
1970 CB 350 CAFE - Current Project on the bench,
1972 CB 350 K4 Red - Now a Happy Rider ! !
1972 CB 350 K4 Green (My Sons) DONE - YES !,
1st Bike 1970 SL 350 (Brought home in Parts - Trailer/Trunk/Back Seat - I miss that bike),
2nd - Bike Kawasaki 750
3rd - '73 XLCH 1000