78 Free Spirit: Spark plug selection question please (Newbie)

ellis richman /

Hey All, Thanks so much for all you help for the new kid on the block, first moped ever! I was fortunate to find a 78 Free Spirit w/ 700 miles, needed a carb rebuild and horn/light/start switches, and a ton of clean-up elbow grease. What looked not so nice became a beauty.

Question: The spec on the bike says NGK B5HS. I heard upgrading to Iridium might be a benefit, but NGK says they don't make this plug in Iridium. I can get the B6 iridium, but the specs are a little different, they said it runs "colder" whatever that means. What's the best spark plug for this bike please? I know a ton of other factors affect performance, but I'm only referring to the spark plug selection.

Many thanks for everyone's assistance!!!

Ellis

free spirit 78 on grass.JPG

Re: 78 Free Spirit: Spark plug selection question please (Newbie)

Every bike is a little different .

I'd buy both and give each a try .

Personally , I find iridium plugs allow an easier start and better overall performance .

Some guys say they can't tell a difference and some say the stock is good enough .

Re: 78 Free Spirit: Spark plug selection question please (Newbie)

B7HS is all I ever use in stock or kitted, points or cdi. Any puch, it’s the only plug you need to use and you can tune around it

Re: 78 Free Spirit: Spark plug selection question please (Newbie)

IMO, b5hs is a little hot. I also prefer b7hs for most applications.

Re: 78 Free Spirit: Spark plug selection question please (Newbie)

ellis richman /

Hey all, thanks! I gave a shot at B6 iridium, and the idle seems smoother, and the acceleration a little smoother too. Appreciate all your suggestions!!!

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