Where did the power from my small engine go?

November 3, 2004 8:42 AM

SmallEngineFilter: My 49cc 4-stroke scooter runs at half the speed it did before replacing a tire and a spark plug.

During the replacement of the tire (went through three tubes as one mechanic after another kept puncturing them, putting them in backwards, etc.) the scooter sat for a month. I see a couple possibilities but none seem very plausible:

1. The gas went bad after a month. Would this have such a dramatic effect?

2. The spark plug, while still NGK, came in a different box from my previous spark plugs -- it was Honda branded. I am in the habit of simply putting the plugs in without adjusting the gap, since the worthless manual for this thing doesn't tell me what the gap is supposed to be. Could this be an improperly gapped plug?

The other possibility is something in the carburetor -- a month ago, after cleaning the air filter, I had a similar problem and brought it to the dealer who said that somehow in the process of opening up the airbox some sort of "substance" had gotten into the carburetor. He cleaned it out and it worked fine (for two days, until the tire blew). This time, however, I haven't even opened the airbox.

Could something be leaking into the carburetor which normally gets burnt away but which accumulates more significantly when I don't run the engine for a while?

It does seem like the scooter runs pretty well for about two minutes after a cold start before it starts slowing down.

posted by IshmaelGraves to Technology (1 answer total)

so the hotter it gets the worse it runs? been a long time since my Vespa days, but i'd say check your plug. You can tell a lot about what your engine is doing by how your plug looks...oily, dry, burnt, etc....and yes, the Gap matters.
posted by th3ph17 at 10:33 AM on November 3, 2004