Its that time of year again, time to check the tightness of your valve port plugs and intake retaining rings. They tend to loosen up occasionally. If the intakes are loose they will lean out the mixture and it will run poorly and be very hard to start. I am referencing the 1909-1912 30 H.P. models specifically. Its easy to do and can save a lot of mystery as to why it runs the way it does.