OK, so I have this Yamaha gas golf cart belt driven I took the motor out and replaced it with the Honda GX 390 but the old primary clutch obviously isn’t the same looking for either adapter to slide in it or a new clutch 1 inch bore keyway
You need to post detailed pics and the exact measurements showing the difference between the output shafts of these 2 engines for us to have any chance of helping you.
Also include detailed pics and dimensional measurements of your Yamaha driven pulley clutch assembly.
We'll also need to know the year and model of your golfcart.
Or here's another idea:
I just googled the search term:
"Clutch for Honda GX390 on a Yamaha Golfcart". I got lots of results showing serveral youtube build videos and also found companies selling driven clutches and lots of other componets for the conversion your attempting.
Have you already done that same google search for the Adaptor you need?