What is wrong with my sparkplug ?

[Wm]

I have a 1983 Kawasaki Prairie KLT 250c. Well it's my dads. Anyway for some reason the sparkplug keeps going bad. He told me yesterday that he couldn't get it running. I checked to see if it had spark. The plug would only spark when you would hold it about a half inch away from the block. It would spark for the plug to the block but not in the gap of the plug. He bought a new plug for it today and it started right up. He took it for a small ride and it stopped running. Now we are back to were we started the new plug will only spark like the old one.
Any ideas to what is making these plugs go bad.
Thanks to anyone that can help. Will.

[TeCaTe_MaN]

Bad Piston Rings :shock: my friends 185s does the same thing, it is getting oil in the combustion chamber and burning it along with the gas and it is baking on your plugs...and instead of buying new plugs all the time get them sandblasted, they will work like new!!

[x200xryder]

could be more then just rings... check your vavl clearance and valve seats to. also DON'T sand blast your plugs. In a machine that runs good, a plug with a sand blasted surface, or even a plug cleaned with sand paper, where's out faster and doesbn't spark as strong as a new one.... cleaning a plug with something like sand paper will get you from the trail to the house. but I wouldn't go no further on one.

[bakeban]

DON'T sand blast your plugs..

then why do they sell sand in a spark plug cleaner, huh i think it is ok.

[TeCaTe_MaN]

i have a sandblasted plug in my tecate, i have been riding on it for 4 months and still riding strong......trail to house my @$$ :evil: :?

[smokinwrench]

Damn you guys get down right serious with your spark plug posts 8) . Heck as cheap as plugs are I just keep new ones around all the time I don't even take the time to clean them, I hope you guys know that you can buy them at your local auto parts store for about 1/2 price of the atv shop. I put a new plug in everytime we go to to Little Sahara or Beaver Dunes I want it to be top notch for the drag strip and trails. I would check valve clearance, and run a compression checke before tearing down your engine to do a top end on it. If the compression is low when checked put a few drops of oil in the cylinder and redo the compression check if the compression jmps way up the rings are bad if the compression stays about the same the valves are not seating in.

Josh

[TimSr]

I havent bought a spark plug in years! What causes a "fouled" plug is when the ceramic insulator around the center electrode gets coated and begins to conduct instead of insulate, and your spark travels across it instead of jumping the gap. Sand or bead blasting is the only way to get the insulator clean again, but doing so will restore it to like new condition, and it will last just as long, and have just as much spark as a new one. I only explain this because Ive seen so many people try to "clean" a plug with a brush, without understanding that carbon and oil deposits on the metal part have no effect on whether, and how it performs and fires. Its only the insulator.

I can clean 10 plugs in less than 15 minutes with my $20 sand blaster. Makes it worthwhile to me! Make sure there is not a single grain of sand in your plug when you reisntall it though!

[AirManCam]

I havent bought a spark plug for my 350x since 94. Also it may be the coil. That happned to my friends warrior.

[Wm]

Thanks for the help. I'm thinking that it may be the coil. I put a new plug in it yesterday and it ran fine for about 10 min. Then it stopped running and had no spark. I think that when the coil gets hot it stops working. Im sure it needs a new set of rings, because the plug dose get black. But it should last longer then 10 min.

[TG]

WM,

an ignition problem can do that, and if you saw "no spark" after it got hot, it aint rings. Id do a compression test to check the rings etc for leakage. Also, look at the plug carefully, oil fouled often looks different that fuel fouled. Oil foul usually looks "oily" and fuel foul looks dry and fluffy, depending on how rich it is. If you lose fire, that fuel cant burn off and it loads the cylinder up and bakes on the plug insulator, so the spark shorts down the side of the plug. I dont normally run cleaned plugs, but during a problem like this, to avoid wasting a box of plugs, id do it for now.

[TimSr]

If you swap a plug and it immediately starts working again, its not your coil. Coils RARELY ever fail, and when they do, it wont run, or wont run right. If you pop a new plug in, and still have no spark (while its still clean), thats a different story. If you are simply fouling out your plugs very quickly, thats not uncommon when you have some other problem.

First verify, when you lose spark, that its not producing any, and its not just another fouled plug, by changing it and restesting for spark immediately, or stick a screwdriver in the plug boot and get a close friend to hold onto it while you kick it over. If they yell profanity at you, you have spark.

[short4stuff]

.....or stick a screwdriver in the plug boot and get a close friend to hold onto it while you kick it over. If they yell profanity at you, you have spark.

LoL

I have down that with a push mower before but I think a trike engne would hurt more .. :!:

[mkramm]

TimSr

What does that $20 sand blaster look like anyway? Something you built or bought?

[AirManCam]

Well I usaly dont build stuff that costs money But he may lol. Im sure he bought it lol.

[TimSr]

mkramm, I bought it on Ebay a few years ago. Its pistol shaped, made of plastic, and has a flip open door in the back of it you pour sand in, and its holds maybe 2 cups of sand. You hook it to a regular air hose, and it shoots sand out the barrel through a ceramic tip. It can also be used to sand blast whatever, but my compressor doenst have the capacity for bigt jobs. I also bought a $5 bag of play sand at the same time, and its still half full.

The other neat one I got out of JC Whitney. It only cost about $8, and runs off 12v. You stick your plug in a hole in this hand held unit, connect the wires to your battery with the clips, and push the button and let it run for about 1 minute. That one is real handy in the field when you foul a plug on something for which you dont have a spare, or to clean your fouled spare before you go back out.