84.5mm bore 84mm gasket... Will this work. I have the gasket laying around.

 

Not positive.

I can tell you though I'm running a 81mm headgasket on a 82mm block. Seems to be fine.

 

although i dont know for sure i just sat and thought about it and i would think that if your gaskets diameter is smaller than your bore you would have some gasket forming a little lip and that would cuase your motor to eat up some gasket and poop it out. and that doesnt sound to appetizing.

 

i will buy the gasket from you!! what motor its for??

 

It will work but be careful. It was never a problem for me going .5mm to small with the gasket but get too much and piece of the gasket will break off due to combustion and will them nick up the cylinder walls/valves/head/piston and it is overall bad.