I am not a mechanic, however I have replaced impellers in Yamaha, Evinrude, Force and Mercury and they were all basically the same. Each one has its own little trick, but they were all easy. The Yamaha is a 40hp 2 stroke, but it was probably the easiest of the 4. I have put 2 impellers in that engine over the last several years and it is only about a 45 minute job. I would suggest getting an engine manual for your specific model and it will walk you through the job. Clymer’s makes a good manual. See the link below. Good luck!

http://www.clymer.com/Book.aspx?bid=...s%2c+2000-2003