possible??

can i put a tach on my mini bike it has a 6.5 hf clone and i have another one with 3 hp briggs

Ive got a 6.0hp brand new techumsen...i also have a mini-baja ungoverned 6.5 and a doodlebug i wanna put the new techumsen on the doodle bug is this good idea or should i put the techumsen on the mini-baja and then the6.5 lifan crap on the doodle??? and how do i put pics on here?????:out: