I've heard Belize are charging an entry fee these days. $100 USD rings a bell? This for US passport holders, not everyone. Not sure on this, any confirmation? It's called a reciprocity tax, as this is what US charges their nationals to enter USA. This is now in place in several Latin countries, usually only levied when flying in, not entering via land border. Not sure on Belize.
Hope you get a chance to visit Cancun (very cheap rates now for fancy Hotels) and Isla Mujeres. The Cayes (pronounced "Keys") off the Belizian coast are a trip as well.
This time of year would be good to ride the main road out of Belize City up to Guatemala, then up to Tikal. Beautiful country. Years ago it was all dirt road, now it may be paved, no idea. But well worth the ride.
Look over on ADV, several riders hanging out now in San Cristobal de las Casas, Xela (Guate) and of course Antigua, Guat. Also, as always, lots of riders will be found riding around Lake Atitlan, Panahachel, San Pedro, all around the lake. Good luck, have a safe trip.