5 gal ? thats quite a bit !
I do have to say, i have an engine that is even more of a *&#%$ to start .. its a RB Concepts .21 buggy engine that puts out over 3HP. When new, i had a hard time cranking it with a wrench with the plug off !! had to turn it over about 1000 times before the starter box would actually turn it ... so looking at the YS80 ...

it could be worse
Wojtek