ohh well that rules out rebuild either clogged jet or since its a fresh rebuild take it easy mine used to knock if i dogged it to much after i rebuilt it

i prefer the hondas over yamaha

will last forever unliek the yamaha

The 450s with auto decompression are great bikes. I had a yz400f for many years and still regret selling it. Make sure your hot start isn't pulled out or the choke.