My 115 runs rough from idle up to about 2000 rpm. Over 2000 rpm it runs fine. Has good starting power and does not normally die, sputter or stall from a start, but if I hit it real hard and fast I can force it to die. It always starts fine - cold or warm. I noticed today that it was backfiring/spitting slightly (about once on the down rev) when reving the engine to warm up - say up to 1500 rpm and back down - but otherwise doesn't exibit this behavior. Doesn't smoke any more than normal. I have only owned this motor for about one year so don't know the history. Does this sound like a timing problem or carburator problem (cleaning or adjustments).<br />Thanks!
