I bought a new tach from bailey's. I put it on my 660 that has only 1 tank of mix through it. It says that its only getting 11500 rpm. The saw is screaming at wot no blubbering at all if anything I think it's running lean. I have never used a tach on a chainsaw before. I just clip the alligator clip on the spark plug wire right? Any info is apprecciated.