Unless you put a rather large amount of oil in through the plug hole, it seems your piston rings are worn considerably. Has the engine been smoking and using a substantial amount of oil?

Here is the abbreviated workshop manual for the GV150 and GV200, which hopefully bear some resemblance to your GV400:
http://www.honda-engines-eu.com/en/images/1004.pdf

I suggest you have a look through the manual and decide whether you want to overhaul your engine. If it is not smoking badly, it can probably be made to run fairly decently without an overhaul, and we can discuss that.

Are you certain your normal spark plug is clean and is sparking properly? If you are sure of that, the next step would be to check whether the engine has a fuel supply problem. This can be done by putting a spoonful of petrol in through the spark plug hole, installing a reliable spark plug, setting the controls in the fast run position (no choke), and pulling the starter several times. If it starts and runs briefly then stops, your problem seems to be in fuel supply, and we can talk about how to overcome that.