Forum

[simon]

Yes my lawn mower does the same. It's soot though rather than carbon. If the bike is burning oil the plug can look filthy but still work. The time that they foul in my experience is when you have one sector of the carburetion wrong and the fuel burns producing soot. My Ducati did it when the throttle pumps cut in. Perhaps it's a change of mixture on a hot plug as simply starting too rich doesn't seem to be as instantly fatal.

[Bet]

My Electra gets used five days a week running fine. If I briefly run it up on a Sunday (just to check it works),it is guaranteed to play up the next morning. Fit a new plug and it is great until next time I am stupid enough to check it.

[Norm]

< I pinched this from the Supersport forum this morning>

Hi all,
I've found that modern 98 octane pulp can cause unusually easy plug fouling because of the chemicals they use to make the shit,in fact the local Ducati dealer recommends not to use 98 especially one particular brand.
Personally I've always preferred to run 95 in all my road bikes these days as I can't find any seat of the pants improvement in power or economy to justify the extra 10 cents a litre.I used to have problems with the Bandit & Triumph 1050 fouling plugs but don't anymore.

[Frank]

In nearly 40 years of motoring, bikes, cars, vans, boats whatever I have only had one plug fail on me about 30 years ago in a car. Motorcraft plug if I remember rightly. I even took over a 2 stroke bike which the previous owner said ate a plug every 50miles but I never had a problem in 30000. Is this a record or have I just been lucky?

[Tim NZ]

Internationally, leaded petrol contained up to .45g of tetra-alkyl lead per litre, though typically the levels was between .2 and .3g per litre. As well as increasing the petrol’s Octane rating, and acting as a valve seat protector, it also acted as a catalysis that burnt off carbon residues from spark plugs and helped to keep them clean. Along with the ‘lead’ were organic chlorides and bromides which further prevented excess fouling of Plugs and lead oxide deposits on piston crowns. None of these ‘scavengers’ are present in unleaded petrol.
The typical density of unleaded ‘Super’ petrol world wide is 0.750 Kg per Litre, compared to 0.735 Kg per L for leaded petrol. The higher density of unleaded petrol provides greater energy content per litre, but requires a slightly LEANER air-fuel ratio to maintain the correct chemical balance during the combustion process. In the real world this equates to a 1-2% change.

Mean time, dont just keep fitting 'the same plug' go hotter, projected tip, and or close down the gap a few thou.

[jaffa90]

Sounds good tim,
jaffa90 Subject: No Ethanol in MURCO super unleaded fuel
With a small plastic pop bottle put 20mm of water in it and mark it with a line, next put approx same fuel in as well and shake with the lid on, with NO ethanol in it the two will not mix, but WITH ethanol in it the mixture goes cloudy and the water level drops. Also i`ve never studied the fact that ethanol is more dense and could effect the fuel level in the carb / s if you use this crap fuel.
I would have thought a weaker mixture with this cr*p fuel.

[Norm]

Frank I wouldn't be too smug, you may have been lucky but if you do get a plug problem it will drive you to despair before you get it sorted

[Presto]

I’m with Frank here. In 50 years riding and driving – two strokes and four – I’ve never had a plug ‘fail’. I’ve replaced plugs but never have had one to fail.

[Bet]

Norm,thanks for sharing the piece about Ducati's, shall fill up with standard fuel this week and see how it goes. It would be nice if it were to be an 'out-side' source causing these problems. Dread to think how many plugs I have changed over the years, I am envious of anyone who has not had to carry spare ones. Might have to buy shares in NGK.

[Norm]

Bet I'm with you I had a horror trip around Tasmania a few years ago, can't remember how many plugs I went through but I was getting about 150ks on a brand new plug. One day I think I fitted 3 brand new plugs, one in the morning, another after lunch and another towards the evening. I was buying plugs in a six pack and the dam thing was a single cylinder