I recently repowered from Yamaha 1994 150 carbs to leftover Yamaha 2008 150 carb motors. The speedo lights up as expected but the tachs show no sign of life even though they worked perfectly with the previous motors. They are definately getting current. I just wondered if anyone knew or had experienced compatability problems with the newer motors and older tachs? Desperately trying to avoid spending $600 for what seems like no reason. Thx in advance.