Finding a replacement recoil / pull start assembly should be easy, right?   

Many of the big manufacterors like Honda and Robin have variations to their pull starts.   Some make them lighter and some are over built for heavy use.   The main area where you will see the changes is the starter mechanism on the underside of the pull start.   

Looking at the Honda GX160 recoil assembly as a case study you can see (in the photos) the different types of mechanisms the same Honda GX160 has come out with.   There is a rarer unit that had plastic paws come out of the centre. This isn't in the photo.  The most common is the steel flat tags and then the round steel bars.  These pull starts need a starter cup that has windows cut around it like the one pictured.   The pull start that has plastic tags has a starter cup which has no windows in it.  

If you are unsure about whether a recoil assembly is the same as your original unit you are welcome to send us a photo of the pull start showing the mechanism.  If you dont have that a photo of the starter cup on the engine can also help us work out what is the correct part for your machine.