c#和Asp.net web api中的URL编码

我有一个ASP.NET web api，接收web请求并返回Json数据。
浏览此URL:
http://1.2.3.4/api1/api/values/mypartname将返回以下json字符串:

{
    '"PartName'": '"mypartname'",
    '"PartDes'": '"53.6X53.6APA/ALIM1NOTPAK'",
    '"PartLocation'": '"A36'"
}

但是当发送一个包含空格或引号的部件名称时，像这样:http://1.2.3.4/api1/api/values/my part na"me我得到404 - File or directory not found.错误。
我正在使用json和.NET 4 Console application，如下所示:

static void Main(string[] args)
    {
        try
        {
            string partName = "TAPE 56 3M 3/4'"";
            WebRequest wr = WebRequest.Create("http://1.2.3.4/api1/api/values/" +
                HttpUtility.UrlEncode(partName));
            wr.Credentials = CredentialCache.DefaultCredentials;
            HttpWebResponse hwr = (HttpWebResponse)wr.GetResponse();
            Stream dataStream = hwr.GetResponseStream();
            StreamReader reader = new StreamReader(dataStream);
            string json = reader.ReadToEnd();
            //some json parsing function
            des(json);
            reader.Close();
            dataStream.Close();
            hwr.Close();
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
        finally
        {
            Console.ReadKey();
        }
    }

在这一行抛出异常:HttpWebResponse hwr = (HttpWebResponse)wr.GetResponse();异常消息为:The remote server returned an error: (404) Not Found.

我做错了什么与mypartname ?我还尝试手动替换有问题的字符根据这:HTML URL编码参考和使用这个函数:Uri.EscapeDataString(partName)，但没有运气。

编辑
这是routeConfig的定义:

        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
        routes.MapRoute(
            name: "Default",
            url: "{controller}/{action}/{id}",
            defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
        );  

和api GET方法:

// GET api/values/5
    public string Get(string id)
    {
        List<dummy> dummies = new List<dummy>();
        string con = "user id=sa;" +
                     "password=1234" +
                     "server=someServer''someInstance;" +
                     "database=game; " +
                     "connection timeout=30";
        //SqlConnection sqlConn = new SqlConnection(con);
        using (SqlConnection sqlconn = new SqlConnection(con))
        {
            sqlconn.Open();
            StringBuilder sb = new StringBuilder();
            sb.Append("SELECT PART.PARTNAME,PART.PARTDES, PARTPARAMA.LOCATION ");
            sb.Append("FROM PART LEFT JOIN PARTPARAMA ");
            sb.Append("ON PART.PART = PARTPARAMA.PARTPARAM ");
            sb.Append("WHERE PART.PARTNAME = @part");

            using (SqlCommand cmd = new SqlCommand(sb.ToString(), sqlconn))
            {
                cmd.Parameters.AddWithValue("part", id);
                SqlDataReader sdr = cmd.ExecuteReader();
                while (sdr.Read())
                {
                    dummies.Add(new dummy
                    {
                        PartName = sdr.IsDBNull(0) ? "Unknown" : sdr.GetString(0),
                        PartDes = sdr.IsDBNull(1) ? "Unknown" : sdr.GetString(1),
                        PartLocation = sdr.IsDBNull(2) ? "Unknown" : sdr.GetString(2)
                    });
                }
            }
        }
        if (dummies.Count() > 0)
        {
            string json = JsonConvert.SerializeObject(dummies[0]);
            return json;
        }
        else
        {
            string json = JsonConvert.SerializeObject(null);
            return json;
        }