i have a big bore for 84r. i think it might be 279cc but not sure. anyone know? im going to get it bored out and was wondering what kind of piston to get. any help greatly appreciated. thanks

 

You probably have a 300 big bore kit. I have 2 84 atc 250r's. One has a big bore 300 kit for it. It was sold by honda. The dealership has it on microfiche. Good luck trying to find a piston. I have had the bike with the kit for about 4 months now and have only found a .100 over piston for it which is the last bore size. It was also the last one that honda had. They don't have any more pistons. You can still get the head and cylinder but no exhaust flange, pistons, and rings. So it is kinda pointless to have. Also my 84r that doesn't have the big bore kit is much faster than the one with the big bore kit. I have more mods done to the other one but the 300 kit in my opinion isn't worth the money. You will be better off keeping the stock head and cylinder, you can find pistons for those.

 

i thought about getting it bored all the way out. i wonder if i could still get a sleeve? i plan on keeping both cylinders just swaping occasionally. would i need a bigger carb. i was thinking of the 34mm off my 86 along with the reed cage. does the 300 require a different exhaust flange.

 

I don't believe that the sleeve is still available. You will have to send the cylinder off to have one made. I'm sure you will have to get a larger carb. I am running a 39pwk on one bike. On the one with the big bore kit it had a 34mm carb on it. The exhaust flange is a little different for each cylinder also. Does your big bore kit look like it's not painted? If so then it is the 300 kit. They are unfinished. The inside of the cylinder should measure 76mm. My stock cylinder is bored .80 over and is 72mm now. There is quite a difference in the size.