Android SQLite Bulk Insert Using Transactions

I have an insert statement and it takes my app about 25 seconds to insert ~1000 rows. I'm trying to use Transactions to speed up my processing time but I'm having trouble implementing it.

Here is my method for inserting in my DatabaseHandler:

public boolean insertQuestions(String gid, String qid, String qname) {
    SQLiteDatabase db = this.getWritableDatabase();
    db.beginTransaction();
    try {
        ContentValues contentValues = new ContentValues();
        contentValues.put(KEY_GID, gid);
        contentValues.put(KEY_QID, qid);
        contentValues.put(KEY_QNAME, qname);

        long result = db.insert(TABLE_QUESTIONS, null, contentValues);
        db.setTransactionSuccessful();
        if (result == -1) {
            db.close();
            return false;
        } else {
            db.close();
            return true;
        }
    } finally {
        db.endTransaction(); //Error is here
    }
}

I'm getting the following error when I try to run the above method:

08-28 15:50:40.961  20539-20539/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.murrion.navigationdrawer, PID: 20539
java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteDatabase: /storage/emulated/0/testapp3.db
        at android.database.sqlite.SQLiteClosable.acquireReference(SQLiteClosable.java:55)
        at android.database.sqlite.SQLiteDatabase.endTransaction(SQLiteDatabase.java:522)
        at com.murrion.navigationdrawer.utils.DatabaseHandler.insertQuestions(DatabaseHandler.java:197)

The statement is being run in an Asynctask method in my Activity.