From:Brad Romines
Subject:Spark Plug for a 1957 165cc Date:Sat Apr 6 11:00:07 2013

First time to the exchange as I just inherited a 1957 165cc from my dad. It has been sitting since the 1970's so I have some work to do. I am boring out the head to .060 as its currently at 0.040. I am having trouble with the simple task of figuring out what spark plug to use. It looks like it should be a #4 but the last one in the bike had a #5. It also looks like the gap should be .025-.030. Any suggestions on a more modern plug or if #4/#5's are avaible?