just finished getting my little 110 running again after testing found that the cdi was bad. Got the new one installed and noticed that the brass fitting in the spark plug boot was missing. Ended up finding it but could not get it in for the life of me. Bought a new boot and all was good.. Plugged the old cdi back in and it ran fine.. go figure a $5 part and a miss diagnostic and its something i would have never thought to do is pull the boot off and test for a connection between both ends

 

I had a similar off the wall issue with spark the other day with a customers quad. It had no spark. Traced and tested all the way back to the stator. Stator tested fine, but still wasn't getting spark to the plug. Then I noticed one of the pins in the stator wiring connector was really lose. (found it after I accidently grounded my spark plug tester while trying to crank, and it started the motor.) Bent the pin back out, pluged it in, and presto!! 2 hours of tracing, testing, and throwing my tools in frustration for a loose connection. I was mad but couldn't do anything but laugh at how simple it was. I was always told to look for the simple things first when it came to motors, but after working on so many motors with so many major issues, you tend to forget the simpler stuff.