RE: question about loosing air filter?
Im sorry, but i gotta disagree with some people here. You said you ran for 10 minutes without a filter? Thats a long time. Waay too long in my opinion. The fine sand, and dirt that gets in the motor is what kills it. It basically gets in there, and acts like a sand blaster on the piston and sleeve. Even though you were running in a grass field, you will still pick up alot of dust and debris. Especially since you said it sounded wierd. If you feel experienced enough to do so, take it apart, clean it, seal it, and zip tie the filter on this time. You should try to hook up with someone experienced that lives near you. Ask them to lend a hand.
Matt