A bit of history. I bought this machine last fall from a fellow that said it had a busted gearcase shaft. I was told the machine had undergone some engine rebuild and many new parts had been added. Upon getting back home I started checking things over and found coolant in the oil case on the clutch side. So I removed the engine and disassembled it. I replaced bearings and seals throughout upon reassembly. The piston looked to be new with little or no staining from being run. A new head gasket was installed and I put the engine back into the chassis. I disassembled the carburetor and found coolant in the bowl. The carb was very clean so after blowing it all out I reassembled it and installed it on the engine. At that time I inspected the boot and looked in at the reed valves and they appeared to be in good shape. I repaired the gearcase and replaced bearings and seals in it and then installed it into the machine. New chains and adjustments were made and this spring I rolled it out and gave it a start. It took right off idling very nicely but upon accelerating the throttle it bogged out almost shutting down. I removed the carb and checked all the jets and ports, blowing them out again. I noticed the main jet was a #270 which I believe is way to much so I replaced it with a size #230. It still bogged out. I checked the compression and it was 120Lb. I checked choke seat and it was good. Gas flow is good. New spark plug. Air intake is clean. Idles beautifully but still bogs on acceleration. I am lost for answers.