I bought a tiny tach for my 94 Rude 88spl. Tried it on a Tohatsu 25c2 and seemed to read double the expected result. Should the tach work the same on each motor or can I chalk it up to interference on the Tohatsu from the other plug wire. I think I read somewhere on this site that the tohatsu fires both plugs but that may have been for a 4 cycle. Anybody got a clue?