stock IsABike(vehicleid)  
{
     new result;
     new model = GetVehicleModel(vehicleid);
     switch(model)
     {
         case 509, 510, 481: result = model;
         default: result = 0;
     }
  return result;
}

forward IsABike(carid);

public IsABike(carid)
{
  new bikeid = GetVehicleModel(carid);
  if(bikeid == 509 || bikeid == 481 || bikeid == 510)  return 1;
  return 0;
}

else if(IsABike(newcar))