Fouling Spark plug

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Fouling Spark plug

Postby taro » Wed Apr 20, 2011 2:47 pm

Something is causing my spark plug to foul up.
It worked long enough for my boyfriend to drive it to and from a hardware store a mile away, but now it only runs off and on.

We get good spark, and we've cleaned the ignition points, but for some reason, the plug keeps fouling and we don't really know why.

Anybody?
taro
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re: Fouling Spark plug

Postby mountainmoped » Wed Apr 20, 2011 5:11 pm

Too much oil if premix or stuck float in carb, or stuck open check valve in oil injection system.
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re: Fouling Spark plug

Postby John » Wed Apr 20, 2011 5:13 pm

What is your fuel ratio? What moped is it? What heat range/number of plug are you using? Any modifications? What jet do you have in the carb? Muffler coked up? Compression? Choke sticking on? Haha, must be some more, but I am at a loss right now.
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re: Fouling Spark plug

Postby taro » Wed Apr 20, 2011 10:24 pm

It's running!

Tonight... That's more than I can say for the past couple of days!

We'll see how long for. More extensive tests tomorrow. I cleaned off the spark plug again, and we emptied out the fuel (which looked like it had very little to no oil in it) and replaced it with a fresh mix. (which is really something we should have done earlier) It started right up twice in a row for two rides around the block without stalling. :)

It is a General 5 Star ST with a Minarelli motor that takes a 40:1 mix. It's currently a new Champion L86C spark plug. I checked it after my two laps and it was dirty again, but not wet and covered in grime this time.

There aren't any modifications and the choke isn't sticking, it's definitely popping up when I give it full throttle. I really don't know about compression, though.

If I have problems with it again tomorrow, I'll definitely have to check the rest of those things that you two suggested. Thanks!
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re: Fouling Spark plug

Postby 52DLegend » Fri May 20, 2011 11:57 pm

i assume this bike you may want to decarbbon the head and get a bottle of decarbbonizer from your local dealer (mix via bottle instructions) mix the heavy carb mix (2oz per gal) for first tank and run the lighter mix (1oz per gal) next 2 tanks then treat every other tank with lite mix to keep clean.
it perked up my honda with about 8k on it.
I think so far out of the box, i lost the box!
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