fouling spark plugs...

[atlantic_salmon]

hey boys, a small question for some of the boffins, i have a small 6hp yamaha,
it came fitted to a small tinny i brought of another ausfisher, the problem is that
when i run it for more than 10/15 mins the spark plugs foul up and it takes
10/15 pulls to get it going again, when the plugs are clean it starts on only half
yank/pull/tug (funny how a yank fits right in there) the colour of the plugs when
removed is black, like a black tar black, i have replaced the spark plugs with
new ones and the problem persists, it runs on a 100/1 mix (thats what the
plastic decal says) i have tried it on 90/1 and that made no differance at all, any
suggedtions would be greatly appreciated....

[BM]

Going to 90:1 would be adding oil and making your problem worse. Are you surer you have your mix right as it sounds like you have too much oil.

100:1 is 10mls per litre. What are you mixing to?

The plugs of a well running engine should be a tanny clour on the insulator of the centre electrode.

Are you trolling and this occurs or at speed?

Cheers

[blaze]

Have the wrong plugs been fitted, to cold of a plug will cause this. The temp range of a plug is worked out by how much porsalen covers the electrode, the more the electrode is covered the cooler range of plug, the more exposed electrode indicates a hotter plug
cheers
blaze

[Roughasguts]

Plugs are black, wet and oily or just black?
Hows the thermostat she running cold or getting up to temp ?
Has any one played with the mixture on the carby setting if it's too rich, runs too cold and fowls the plugs.

Yup BM is right 90:1 is more oil, are you using outboard two banger oil, ?
Not the stuff for your L/mower that burns at a higher temp and will fowl at lower temps.

[atlantic_salmon]

thanks boys, i ment 110/1 (still had hairy eyes from getting up to watch the reds bend over or play or what ever they call their display) the plugs are an oily black i dont know if the carby has stuffed with, the spark plugs, i got the marine ones from super crap auto they were the same as the ones that came with it, with the mixing i brought the obligitary blue capped round cup looking thing with the markings on the side of it, im not to keen on taking it to a marine mechanic as the bill would be more than the engine is worth, any more advice please...

[Roughasguts]

Got to get her hot, not over temp but long enough flat out running to burn all the oil out the crank case.

[Hamish73]

I doubt it an 'oil fouling' problem as I run 50:1 on my 6 and 15 with no problems.
Soulnds like it is rich on the fuel side. When it wont start, if you hold the trottle fully open does it start easier? If so this indicated a rich (fuel) condition. Opening the throttle fully lets more air in, which in effect leans out the mixture for starting.
Does it have a fuel mixture knob on the front of the engine?

[rubba]

get it serviced mate

[atlantic_salmon]

Rubba mate, wish i had the bucks, but just brought a house and with all the lovely expenses incurred it just aint an option for a few months, Hamish it does start a bit easier (5/10 pulls) when im giving it a bit of curry, roughasguts you are dealing with a pagan here mate, can you run us through the idea of running it hot to burn the oil out of the crank case, cheers mate...

[Roughasguts]

No worries, that's an easy one to answer.
Have fresh fuel and oil, an empty boat to get max revs for the motor. And run the boat flat out for 10 minutes, that will heat up the oil in the crank case and burn it out.

After 10 minutes, it should idle and start a hell of a lot better, if it don't we better start looking at a compression check, a carb clean, a decarb for the head, and check the timming.

But first do the flat out run.

[atlantic_salmon]

Thanks mate, will be taking the fly rod down the pine on wednesday after work, will put in the small tank and leave the battery at home and give him some stick, once again thanks...