Changed oil this weekend...

[drm7]

I finally got around to my mower (Husq w/15hp v-twin kawasaki engine). I changed the oil using Mobil 1 10W30 SS. I cleaned the air filter and replaced the spark plugs. Before changing the oil I ran a couple ounces of seafoam in the crankcase and in the gas for about 1 1/2 hours of mowing. I noticed that one of my sparkplugs was pretty clean and the other was kind of sooty black. Both electrodes seemed in good shape. What would cause the sooty black plug? This mower is about 2 years old with 58 hours. About 45 hours on Mobil 1 10W30 tri-syn before this weekends change. I did not add any oil during this time and it remained pretty clear up until about 6-8 hours ago then started darkening.

Thanks!

 

[drm7]

Any ideas on why one of my spark plugs was kind of sooty and black? I bought the Husq w/Kawasaki motor for the reputation and hope to get years out of this mower.

Thanks!

 

[drm7]

I went to champion plugs and found this on fouled plugs:

"Fouling is when the spark plugs firing tip becomes coated with excessive fuel, oil, or combustion deposits so that it is unable to produce a spark. A plug can become fouled from continues low speed driving, improper spark plug heat range (too cold), improper timing (over-retarded), too rich an air/fuel ratio or an oil leak into combustion chamber. A variety of self-cleaning features are designed into most plugs to reduce fouling."

My plug was 'dry fouled'. The mower seemd to run fine, I only changed plugs as a matter of habit. A guy at the parts counter had told me to run premium gas. From reading the part about improper timing should I run 87 oct? I have been running 89 oct. Like I said, I have a twin cylinder so I would think both plugs would tend to have the problem if it was timing or air/fuel, etc. It doesn't seem to use oil so I don't think that's it.

 

[blano]

Its not uncommon for one cylinder to run hotter(thus cleaner plug) than the other in a multi cylinder engine like this. I wouldnt worry about it and technicaly the plug wasnt "fouled" if it was still working. BTW i dont think adding seafoam does anyhting but empty your wallet and increase the risk of damaging something. The thought of adding a light viscosity kersoene/oil mix like seafoam gives me the hee bee jee bees.

 

[MolaKule]

drm7,

Using 89 octane non-ethanol fuel with 1 oz. of Neutra per five gallons of fuel will keep plugs and carbs clean throughout the whole year, while stabilizing the fuel as well.

You may need to trim the air-fuel ratio to a slightly leaner mix. Most new carbs have limit tabs, but there is a small amount of adjustment that can still be made.

 

[Blue99]

What Blano is suggesting is that this is simply a characteristic of your V-twin engine. I remember reading a similar statement within the last week , but can't honestly remember if the application was a riding mower or aviation.

The heat range of the spark plug would be an easy thing to experiment with. Install a hotter plug (lower number) & monitor it after each use.

From the NGK site: Whether the spark plugs are fitted in a lawnmower, boat, or a race car, the spark plug tip temperature must remain between 500C-850°C. If the tip temperature is lower than 500°C, the insulator area surrounding the center electrode will not be hot enough to burn off carbon and combustion chamber deposits.

More at ngksparkplugs.com Tech Info.

 

[jsharp]

One thing to look at on the "sooty black" plug, provided it's dry when you take it out. Rub the electrode into the palm of your hand. If the "black" comes off easily it's likely fuel, if not, it's likely oil...

[ October 14, 2003, 03:15 PM: Message edited by: jsharp ]