K.H.
Well if you have found something that works then stick with it. A friend of mine used soap too to get her daughter to listen and it worked. My son is mouthy too and I use to the time out method which works and he is immediately sorry. Just as long as you using the soap as a last resort and honestly I have threatened to use soap on my son and that was all it took for him to listen and I have never needed to actually use it. Look at how well behaved children were 30 years ago and soap was used then so why not? I also praise my son when he is being well behaved instead of just yelling or time outs when he is misbehaving, so then he will hopefully understand what is acceptable behavior.
I love Harleys too, I dont have one but hopefully someday i will, its in my blood!
K.