My Honda 4514 lawnmower project needs a new cambelt. Not available from Honda here but can get from USA at big money.

Are there any companies that list belt sizes rather than application so I can get one that way

Cheers

If you can find an manual online for the mower it should have the part number which you can search on the web for. However very likely is that the engine is used in many machines and doing a search on that might be more fruitful. Parts for ride ons can be expensive. First time I've heard of one not having a push rod engine and usually it's a Briggs and Stratton.

Honda 4514 has a Honda inline twin cylinder ohc engine about 380cc

https://www.youtube.com/watch?v=Dj5kfy-R180&t=115s

RS Components do timing belts by pitch width and length, whether they are suitable for an ic engine I don't know.

If THIS is the correct engine then part number looks to be "BELT, TIMING 14400-ZA0-003", google shows plenty suppliers.

https://www.gardenhirespares.co.uk/14400-z0d-003-genuine-honda-belt-timing-61yu7.html £37.80 which seems a bit steep.

Davie

Company called Bearingman have always been good when I've needed belts (Dry sump pump belts for one)

All the parts to rebuild my EU2000i came from these guys.
Your gx360k1 is listed, but they're not showing cambelt stock. Suggest you give them a call?

https://www.lsengineers.co.uk/honda-gx360k1-ga01-engine-spare-parts.html