Buy a spark tester at an auto parts store. Under 10.00. Has a grounding clamp. I check for spark against my painted outboard motor engine blocks. The heavy enamel paint cant hold back 10,000volts.
I brought new points for my E50 and they lasted 10 miles before the bike started to run shitty. I cleaned the originals and reinstalled them and they were trouble free for the a few years that I had it.