Hyper Engines Argh!!!!

[greenplane]

I am a seasoned RC guy , i buy and sell maintain etc
However I have recently had two problems with Hobao Hyper engines, both dont and wont start , all factory settings warming of engine etc but nowt, plugs are good and work out of engine fine and in fact in other engines great, fuel is new 20% , But both a hyper 21 and a hyper 32 will not start the larger went back as it was a shop bought engine as i work in a shop too. however the .21 is mine for one of my own customers and no way will it start.
So any ideas thoughts would be much appreciated
Thanks
Mike