Mix ratio is fine, but do NOT break-in on the ground!
That 4500 rpm/2 hours is one of about 7 errors in TH/Hobbico/Hobby Svc DLE20 manual.
Prop it the way you'll end up flying it, tune it correctly, then go fly it.
Also, put an NGK/CM-6 plug in it, the stock DLE/3 plug has reliability issues for some users.
NGK's actual stock number is 5812
Honda number is 98052-56471, it's an NGK CM-6 in a Honda box.
Jody's gas engine tuning tips (pdf files);
http://www.rcuniverse.com/forum/fb.asp?m=10293852
More info on the DLE20cc.......
NEW DLE 20cc Gasser! (Data & Links 1st Post)
http://www.rcuniverse.com/forum/m_9863953/tm.htm
LOADS of relevant info there, most notably the very first post.