Too Much Too Soon?

I just did my first Oly last weekend and was thinking of doing another race on September 7.  I did OK in the Oly but I wouldn't say it was a lot of fun as I pushed pretty hard and really went out too fast.  The race on the 7th is a 2K swim, 60K bike and 15K run, which is a bit longer than I've trained for, but I was planning on using this race more as a training exercise, taking it easy and trying to enjoy myself.  Any thoughts?