ha ha ha you got Harbor Freight in Modesto??
for kingkoopa
That rattling is probably a loose chain hitting something, suggest you check chain before you throw it, btw that mini will hit about 20mph + if your like 100lbs or less wet.
Remember that 2.8 hp Chicom is about 2hp US Briggs flathead.
If not the chain then you have a big loss in power probably due to a bad plug or tuning. These little engines are NOT easy to get running correctly, (more like damn near impossible and not worth the effort). Think upgrading to a HF clone as you will be much happier with it in the long run.