Ok, so just bought a 1975 XS650B with a title for short money. Motors locked up from sitting for 20+ years. pulled the engine and tore it the top end off to inspect what is going on with the cylinders. Found the exhaust valve on the left cylinder was stuck open, and worst part is that someone a long time ago took the exhaust pipes off so even more crud and water were able to maneuver them selves into the cylinder. my question is what do you guys suggest as my next step. I'd like to turn this bike into a bobber and keep costs down, should i replace just the sleeves and pistons? or go spend the extra money on the big bore kit from mikes? or just find another engine all together? thanks