I have a 1977 yamaha 440 exciter snowmobile with intermittent spark. The switch has 3 positions, off, on, and lights. i have checked it with an ohm meter and it appears to open. But I am confused because if it was open why would I get spark intermittently? Also I have shorted the pin on the other side of the switch with a paper clip and I still did not get spark. Any suggestions?

SOURCE: Hello, I have a problem with an intermittent &

sounds like you have a poor earth connection, possibly between the coil and the frame, try quickly rigging up a cable from the mounting point on the coil, to a bare metal part of the bike (or nagative battery terminal if available), and try again.
Hope this helps

SOURCE: I have a 1992 Yamaha Big Bear 350 Moto 4. With the

check the wiring where it comes out of the side cover on engine mine was same way and it was bare wires there

SOURCE: Thanks for all the previous suggestions, it seems

Hi and welcome to FixYa,

Initially, a couple of checks when starting:

• verify consistent + 12 on the black/white wires on the ignition coils and spark unit;
  
• high pulsating ACV on the yellow and blue wires to the ignition coils from the spark unit;
  
• low pulsating ACV (0.5 VAC) on the yellow & white pair and the blue & white pair to the spark unit from the pulse generator.
  

Testimonial: "many thanks, still trouble shooting, will keep you all posted."