Topic: Big bore sizes

[Terry in Australia]

Its all in the tool geometry and knowing what to use..
 I can peel off 100 -120 though in steel, on my little South Bend lathe, other have trouble cutting 60 thou.. Biggest problem resulting in inability to cut is RIGIDITY, if machine is badly worn or missing parts or needs adjusting, it can cut poorly..

Nope, mine's in very good condition Frank, and the original handbook recommends 5-10 thou cuts.

[JD_G]

I have a 1976 CB750F and have the entire engine torn down. The motor had 8500 miles on it and I am thinking of boring up to 836cc's but have been trying to figure out if I should replace the stock rods for aftermarket forged aluminum rods. The challenges for me is finding new bearing shells, the machine work on the cylinder skirts for the extra clearance needed with the rods, and trying to determine if I need to balance the crank. Has anyone here done an overbore to the 836cc bore with stock rods and bearing shells? Should I replace everything? I am already doing a top end rebuild but was planning on using the stock cam. The valve guides, springs, retainers, and valves are already on my list of things to do as well as to port/polish the intake/exhaust. Any help would be appreciated.

[754]

Many of us have run 836 with 10.5 to 1 compression on stock roads and lived.
 You got to decide , the cheap low compression is fine for  budgets if you want to cam or headwork now or later, get the higher compression, it works better with those  other things. The high compression sets care often at least triple the price.,

[HondaMan]

IMHO...The 'sweet spot' of the 750's engine design is the bore size of 2nd over, 749.8cc (won Daytona in 1970!). Honda has long designed engines at the 2nd oversize, then stepped down 0.5mm for the original size while allowing room in the head gasket for 0.5mm over the 'nominal' (2nd oversize) bore.

[Jerry Rxman Griffin aka MuthaF'er]

Use your stock rods with 836. Perhaps your bearing shells are still good too. With only 8500 miles you should be good. Your valve guides are probably fine too. The F2/F3 was the one notorious for the valve guide issues and not the F0/F1. I floated a valve on mine when I blew her up. I installed stronger valve springs to help prevent that. Of course now it helps if I let off the throttle for shifts too vs power shifting which is not very forgiving if you miss a gear.