Motorcycle Repair: Do i got the right piston kit??, honda cb900c, wiseco pistons

Question
Hi Gary. I have a Honda Cb900c 1982 and i have to put new pistons  on it. Somebody recommended to get wiseco so i did it  and i got the big bore k985 because they told me they where good and the right ones. I took the cylinders to the machine shop to bore them and the machinist said that i might have to exchange them because i might have to modify a bunch of stuff on the engine to make it run. He said it might be over compression (8.8 to 1 /original - 10.25 to 1/ actual), and the valves might hit the pistons, plus i might have to use special gas.So  i choose to find the answers before start the work. There are to many "MIGHTS" and I'm kind of scared now because the  return date is past and i cant take it back. I would like to have an opinion from an expert before doing something. Thanks 4 your time

Answer
Javier,Wiseco pistons are very good and usually come with all the parts you have order individully and cost less. The kit should have some info on it somewhere as to any modifications you may have to make. The pistons usually have some valve reliefs cut into the top and if it is a big bore kits you will have a special head gasket to clear the piston. As far as with the gas its true you may have to run a higher octane to keep the pinging and the pre-detenation down.Unless the wrist pin is to high in the piston it should not protrude above the cylinder. Set the new piston beside one of the old ones and compare where the wrist pin is located.If its the same then really the only physical change is the diameter. The only other test is a clay test that involves putting the piston on and you can leave the rings off for now. Assemble the cylinder and head with gaskets. Put a piece of plydought or clay on top of the piston. Bolt the head on and tighten the turn over the motor and mash the clay up against the head then pull the head off and see what kind of clearance you have or if the pistons rise above the cylinders.