Owned a '96 600xcr monoblock/single pipe back then, wish I kept my '94 xlt sks until I bored it out 1mm and installed SLP billet heads and it was stronger than it was stock and dead reliable afterwards. Dropped the needles one from top and it finally had better fuel economy than it did new and wasn't as finicky running. If I were to own one again I'd buy an XLT with 34mm carbs, way better.
Boring a cylinder to an available typical oversize piston size is not called "big bore", "big bore" is when you swap in pistons from a different motor, or make new ones, creating a substantially larger motor displacement..
Sled bores are measured in MM, so typical over-bore sizes are .5mm, and 1.0mm.
I believe that pistons are available for that motor in .5mm overbore, and you can use your stock heads. I'll have to reference my parts catalog to be sure.
You are not going to gain anything compared to how much you spend in boring it. boring a cylinder should only be done to correct damage. boring a cylinder as said above is NOT the same as doing a big bore. youre gonna have several hundred bucks in boring it and gain a horse power or 2?! and then when you do blow it up and do NEED to go oversize you may not have any sizes available.
if youre moter needs it-bore it. if its running fine leave it alone.
but if you do bore it you dont need to alter heads.
There's actually 3 overbore piston sizes available for that motor.. .5mm, 1.0mm, and 1.5mm - listed piston prices are included
boring 0.5mm (.0196inch) over, you'll gain 9.2cc's displacement and a maximum of 1.6 horsepower. (~$150 SPI piston set / $375 Wiseco piston set)
boring 1.0mm (.0393inch) over, you'll gain 18.5cc's displacement and a maximum of 3.3 horsepower. (~$412 Wiseco piston set)
boring 1.5mm (.0590inch) over, you'll gain 27.9cc's displacement and a maximum of 4.9 horsepower. (~$412 Wiseco piston set)
Add to that the cost of a top end gasket set (~$60.00) and cost of machining.
You can probably gain more than that just by cleaning the clutches and carbs, and replacing the plugs, wires and caps..
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