Spark Plug Problem

[irelandbiker]

This is my 6.5hp clone engine

After about a minute of driving the spark plug turns like this

The old oil which I changed yesterday 10w40 semi synthetic was very black

I changed the oil and sprayed wd40 into the engine but the spark plug still is black everytime
Does anyone know the problem?

 

[Kaptain Krunch]

running rich, im no expert but it should be a brown color. thats all i can tell you, someone else will jump in with more knowledge.

Does your engine actually fowl out and stall? that doesnt look horrible, but i know its not the right color.

 

[irelandbiker]

the engine runs fine then struggles for a few seconds and eventually shuts off

 

[Affair_driven]

Why 10w40?

 

[irelandbiker]

its all they have in the local shop what do ye use?

 

[Affair_driven]

This oil could lead to engine probs including fouled plugs and a bunch of other stuff. Blow-by (caused by wrong oil) could be reason for black oil, or it wasn't changed at proper interval.
Correct oil is nothing above 10w30 as stated in manual, and they mean it. No small engine manufacturer recommends 10w40.
Change oil to 10w30 dino, not synthetic.
Get correct heat range plug and gap it to spec.
Check for clear air filter.
If you still have problems, post them here.

 

[anderkart]

the engine runs fine then struggles for a few seconds and eventually shuts off

I'll second the previous suggestion to make sure your air cleaner isn't simply plugged with dirt.

Do you suddenly get thick black smoke out of your pipe right before it dies? If so your carbs needle and seat valve could be dirty or defective and flooding your engine with too much fuel.

Also remove your air filter and look to confirm that your carbs choke-butterfly isn't stuck or staying closed.

Any one of these items could cause your stalling problem, they could also explain the way your plug looks.
(that plugs thick black soot is telling you that your either getting to much fuel or not enough air...)

 

[THE HUNTER]

my first guess is the rich mixture, as mentioned by pretty much everyone. lol.

the recommended oil for this engine is 10w-30 (5w-30 in freezing weather)

and having 10w-40 recommended for small engines does happen, though it is very rare now. my mower has 10w-40 recommended for it on the engine (its an early 80s engine). but Brigg's modern recommendations dont include 10w-40.
every manufacturer recommends either straight 30, or 10w-30 for summer use now.


but why not synthetic?
though for general use, conventional oil will work plenty well when its the correct grade and changed when needed, and its cheaper.


and for anyone that is wondering..
"SAE 10w-30" means the oils viscosity will be 10 in winter "w" (0*F or -18*C) and 30 at 210*F (or 99*C)

the lower the number, the thinner the oil.

 

[irelandbiker]

10w40 has always worked for me do i just have to change it reguraly and i checked the air filter that is definetaly not the problem

 

[Kenny_McCormic]

You want 30 weight non detergent motor oil. 10-30, 10-40, etc. are meant for use in engines with oil filters, they keep metal particles and other junk in suspension, non detergent lets it sink to the bottom and keep it from wearing stuff out.

 

[Affair_driven]

Detergent is always recommended.

 

[THE HUNTER]

if 10w-30 is recommended by the manufacturer. 10w-30 is what i put in my engine.

the detergent doesnt keep the metal particles in suspension, but the "other junk" it does. the problem with it sinking to the bottom of the crank case is that it can collect there too quickly.
the detergent also dissolves the sludge and varnish and keeps it from sticking places it shouldnt.

the Briggs service manual says

Use a high quality detergent oil classified "For Service SF, SG, SH, SJ" or higher. Briggs & Stratton strongly recommends the use of synthetic oil.

if you live in a hot climate, 10w-40 should be ok if 10w-30 isnt available.

and yes!! you should ALWAYS change the oil regularly!
thats a major key to long engine life.

your manual says to change the oil every 20 hours of use
and of course check it before each use.

heres the manual.
http://www.harborfreight.com/manuals/66000-66999/66015.pdf

and by the way, your spark plug gap should be .027” to .031”

but unless you are seeing some blueish smoke in the exhaust, you arnt burning enough oil to worry about.

something is most likley wrong with either your carb or the ignition.

 

[irelandbiker]

Could a dirty petrol tank be the problem?

 

[Affair_driven]

If got into carb, then yes.

 

[irelandbiker]

the carb is fine do?

 

[Affair_driven]

the carb is fine do?

Can you rephrase that?

 

[irelandbiker]

the carb is ok

 

[Affair_driven]

Engine is running rich for a reason. Could be float/needle is hanging open causing a rich condition. Dirt/debris would do that.
Check float level for correct spec.

 

[jr dragster T]

Every single plug I've ever seen from a stock industrial engine including Honda and Briggs all look black like that.

 

[THE HUNTER]

Every single plug I've ever seen from a stock industrial engine including Honda and Briggs all look black like that.

yeah, they turn black with normal use, but should still discharge a proper spark.
a few mins is WAY too fast for it to foul up to where it stalls.... a properly running engine shouldnt foul up that fast...
are you sure the plug is actually fouled to the point where it wont produce a spark?

prob shoulda mentioned this earlier, but remove the plug, hook the plug wire up to it, then ground the threads of the plug to the engine block or head.
then give the rope a yank and see if the plug is sparking. (you might not be able to see it in the sunlight. try around dusk)