Talk to the experts.
Same place that OMW sends his cylinders.
Millennium Technologies
920-893-5595
http://www.mt-llc.com/tour/advantage.html

 

erbed seems to have shown they do good work but can you get the stock cylinder to seal with the 105 bore? or are they the right choice for repair of the stock cylinder.

 

When the big bores first came out there was no aftermarket gaskets available other than copper. They distorted from heat after awhile ane leaked.
Some guys even had their head o-ring, but this was on a surface very small and the 0-ring ended up within .075 of bore. They also distorted from heat and after awhile leaked. Cometic came out with a trimetal gasket that had a special coating for adhesion and the 3 layers could cpntrol the heat better and not distort and loose seal.
The aftermarket cylinders can only be ,100" or .050" per side larger, because they still have to line up with the cylinder head. Present cylinder is .300-.325" thick, after a 105mm bore, the thickness would be down to .200-.225".
With Mr HP running a 108.5 bore, just think how narrow the gasket is to the head water passages!!!!!!!!
On a 720, gas only I do not think that the extra thickness(.050 per side) is the main issue for good sealing.

 

so have you had luck boring the stock cylinder to 105mm and getting the head gasket to seal? you say the after market cylinder. I didn't know anyone had luck with the stock cylinder bore over 102mm.