That helps us to identify the engine on that YardStar STA 17. It is a chonda 160F (a Chinese unlicensed copy of a Honda GX120 or GX160 - the name 160F is somewhat generic. The one on the YardStar is a GX120 copy). Here is the 160F:
http://www.alibaba.com/product-gs/1067888584/160F_Gasoline_engine.html?s=p

Here is the Honda GX160:
http://www.justgenerators.co.uk/pages/Honda_GX160_Engine.htm

Here is the Honda GX120:
http://www.cometkartsales.com/store/engine/images/GX120.jpg

With most chondas many of the parts are interchangeable with Honda ones, but unfortunately the deviations from Honda are unpredictable which makes spare parts a sort of lucky dip. Note the Chinese advertisement says "No overseas service provided".

Last edited by grumpy; 25/09/13 08:13 PM. Reason: Add detail