Masachapa is roughly 70 km southwest of Managua, a drive of about an hour on the Carretera Nueva a León and then south through San Rafael del Sur. By car it is straightforward; just follow signs for Masachapa or Pochomil from the capital.
By bus, take any service from Managua's Mercado Israel Lewites (also called Mercado Boer) toward Masachapa or Pochomil. Buses run through the morning and can be crowded on weekends. The journey takes around 90 minutes. Taxis from Managua are faster but negotiate the fare before you leave.