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Court and spark

February 8, 2007

The PX’s tendency to sputter at idle had gotten worse, so last night I finally decided to look at the spark plug.

Regular readers will recall that changing a spark plug on a PX 150 or any vintage Vespa is not a huge deal. Since oil is part of the mix that goes into the cylinder and gets burned, there’s a greater liklihood of spark plug fouling, but automixing means the right amout of 2-stroke oil will usually be present.

Spark plugs

Wikimedia Commons

The plug’s electrodes and insulator are the ideal chocolatey-brown, with the outside edge near the threads showing a bit of carbon, which is to be expected when you burn oil. It’s a bit over halfway to the next service visit at 4000 miles, and there seem to be no other issues.

However, spark plugs are quite cheap. The local big-box discounter had what appeared to be the correct plug for $1.89, but I spend $2.49 at my local independent auto parts store. The OEM plug for the PX is a Champion RL82C, and where equivalency charts for other brands were once plentiful, they are nonexistent these days; the application charts for, *ahem*, mopeds in the manufacturers’ catalogs can be surprisingly inaccurate. In fact, that was the case at the big-box store.

This particular store doesn’t carry Champion plugs. Luckily, the parts guy had an idea what plug in NGK‘s lineup might do the trick. Bingo! He takes the new plug out of the box and it’s identical to the Champion plug, save for two less ribs on the insulator. Some scooteristas swear by NGKs; it’ll be good to get first-hand experience.

See, this is why you buy things from independent retailers… knowledge! The well-meaning but uninformed person in the blue/red/orange/whatever vest isn’t going to be able to help you if your local parts guy has to close up, so support him/her!

In about five minutes, I have the new plug installed. (I said it’s easy!) I start the engine to make sure everything works; it does.

Today, we’ll see how things go.

I fire the bike up, it starts on the third kick (normal for sitting overnight), but seems to be idling with more authority. It continues to idle, even without goosing the throttle, which I was doing until it warmed up.

Acceleration is noticably stronger, and when I come to the light at Nickerson/Dexter/Westlake/Fremont, the engine idles contentedly once I’ve stopped. I head up the slight hill on Dexter with a new vigor. Yes, the new plug makes a difference, and as I said, they’re cheap. If you want, you could even clean and regap the ones you take out, and keep them as spares for group rides and road trips. Or use them in art projects.

My attention is suddenly taken by the beater Nissan Sentra in front of me. What the hell is he stopping for? A jaywalker?! Favicon


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