My Scrambler died on a ride over the week-end. It just puttered than dead. I changed the plug and it started up after two tries. The old plug looks just like it used to...chocolaty brown with some black stuff around the base.

Is there a visual characteristic to look for or is it just dead??? I ask this out of curiosity...it is the first time this happened to me.

 

Black with carbon build-up and wet.

 

The white insulator around tour electrode is probably cracked.

 

Exactly!

 

Dumb question: What exactly causes a plug to fowl?

I have had three 2-strokes so far and it has never happened till now. (Scrambler)

 

Dumb question: What exactly causes a plug to fowl?

I have had three 2-strokes so far and it has never happened till now. (Scrambler)

 

Fowled plug has feathers, Or was that a duck plucker.

 

A fouled plug can have many looks. I have seen many . What usually happens is the ceramic shield becomes conductive , making the spark not jump the gap .

The best thing I can post is this . Diamonds are forever, so are fouled plugs .Cleaning sparkplugs is a waste of time . When in doubt , throw them out .

 

Same thing happened to me one time. I had always looked for the blackened, wet appearance to determine whether or not my plug was fouled. Until one night at deer camp I could only get it to sputter and backfire. I had taken the plug out several times and it was the normal color and only wet every other time I pulled it out. So I dryed it with a lighter about a dozen times and still couldn't get it to run. I put the plug in the plug wire and grounded it against the frame and was getting spark but the darn thing just would not start. I finally gave up and went to work on a 30 pack instead.

The next morning I went at it again. Only this time when I grounded the plug against the frame I could tell exactly where the spark was comming from. It was sparking between the porcelain insulator and the spark plug steel body. I got a new plug and it fired right up. This has also happened on my kids dirt bike.

So, sometimes you can't see a visual sign of the plug being fouled. Especially at night!

I could have avoided all that trouble though if I had thought to carry a spare plug ALL the time. I wasn't that smart though. It's only a 2 stroke what do I need an extra plug for? RIGHT!

 

Xplor sometimes you can't tell by looking at the plug itself.
The best way to check to see if the plug is fouled is take the plug out and pop it on the plug wire, place it on the cylinder to ground it and pull the engine over and watch for a spark.
If theres no spark its fouled, if theres a weak spark its ready to foul replace it.
And don't hold the plug wire wi'll cranking the engine, trust me I learned it the hard way I'm still trying to brush my hair back down.LOL.

2000 SCRAMBLER 400 2X4

SCRAMDADDY400