Wow - I know precious little about engines but 5:1 seems a little heavy with the oil - Wikipedia suggests ratios of 50:1 down to 20:1 for 2 stroke engines - other tables on the web show 16:1
The manual for this machine...
http://ipl.ordertree.com/ipl/339/41adt90c066_tb90bc.pdf
Clearly suggests 40:1 on page 8.
I think the first answer has a typo in it...
Peccavi
June 2009