Cann 773
Not near enough Prop. try 19x11. High Speed Needle is probably to rich depending on how much time is on engine. My needle settings near sea level are 7/8 to 1 out on high speed needle and flush on low speed. There are two other threads I started this month on the 170 DZ CDI that have got a lot of great information in them from many others.

Good Luck.
Dick