Wiring power cord Adapter to connect a Round 3-prong female generator plug to a round 4-prong Gen Trans Switch
I looked up the Honda EU2000i Owner's manual, and it appears these generators are only rated for 120 volt output.


  


I couldn't find much detail on the transfer switch you mentioned, but from what I could find it appears to be a 120/240V transfer switch. 

If you were to connect the generator to the transfer switch, only half of the circuits would work, and you'd not be able to power any 240V loads. This is because the generator is designed to only supply 120 volts, whereas your home (and the transfer switch) work with a 120/240V system.

If you really want to proceed, which I wouldn't recommend. The adapter cord would have a standard 20 ampere three prong plug ("hot", "neutral" ground) on one end, and a four prong ("hot", "hot", "neutral", ground) plug on the other. The wiring would be as follows:


Three prong "hot" to four prong "X".
Three prong "neutral" to four prong "neutral" (W).
Three prong ground to four prong ground.
four prong "Y" not used.


With this setup, only the circuits labeled "A" on the transfer switch will work (or maybe only "B" will work, depending on the internal wiring).



My recommendation; based on the fact that you seem to indicate that the power in your area is somewhat unreliable, is to purchase a larger 120/240V generator. This should plug directly into the transfer switch, and will power both legs (A and B), as well as supply 240 volt loads.