I use a shop tach for small outboard work
http://www.google.com/#q=laser+tachometer&hl=en&prmd=imvns&source=univ&tbm=shop&tbo=u&sa=X&ei=4MmmT8TABcrqtgePyND_BA&sqi=2&ved=0CMwBEK0E&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=fb64cf876c794163&biw=1280&bih=577