I had a K321 rebored to .010 over and the cranckshaft miced down .010 under, ground the valves and seats all cleaned up at machine shop (cost me $180). It has a starter /generator, no balance gears, its on a 1977 -444, owner told me all was original (tractor and engine). Kohler spec #60313d (sn 8240867). I installed a new piston and new connecting rod that matched the rebored and miced crankshaft. The engine idels fine but misses at higher RPM's. (3600 RPMs when it ran ok at higer RPMs) I had to adjust the valve to tappet clearence twice since rebuild, they were way off from specs (.009 I, .018 E) I think this is what is causing it to run sluggish / miss at higher RPM's. A guy who repairs small engines told me that I need to get the camshaft resized (don't know what that means) to match the change in the rod/crankshaft. Is this true, I can not re-use the same camshaft and lifters with a rebored cylinder and miced crankshaft?? Could the cam lifter lobes or the compression release tangs be in bad condition? Any help here would be greatly appreciated, I dont want to keep taking this engine apart.......