To the Op.
Clean all your grounds and check the connections at the ig. switch and starter solenoid, be sure it is grounded well.
On a side note...
Seems like all four if mine, 2 1541's and the 1862, 1860 you have to sit on the seat to start them,they will just crank if you do not sit on it. Do you think that is a coincidence?
Here is the pdf for it.First page says you have to sit on the seat.
https://drive.google.com/file/d/0B9j...ew?usp=sharing