I am dissatisfied with a recent up vote of my reputation. Is there any mechanism on EL&U that will allow me to down vote my own reputation?
You are, by design, prevented from voting on your own posts. If you really think your question should not be upvoted, you can delete it (so long as it does not have upvoted answers; it if does, you would be unfairly reducing the repuation of others).
But you may also need to reconsider your view of reputation. It is not a negotiable currency (unfortunately) or a personal reward; it is an indication that others think this is a useful question, which should be marked out from the mass so that others may consider it. What you think about this is in a sense irrelevant; so long as a question is not closed (which is a more technical point, and depends on the view of experienced users), every question is set adrift on the sea of public opinion, to gather votes and answers as it may.