Spark plug condition

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mattswan2512
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Spark plug condition

Post by mattswan2512 » 16 Nov 2017, 14:41

Okay so i tested my OB in my garden again today and it ran flawless yet again for over 25 30 mins...i pulled the sparks and checked em and found them to be a little wet with oil
20171116_142711.jpg
20171116_142717.jpg
Plug 1

Plug 2
20171116_143048.jpg
20171116_143114.jpg
Whats your opinion does this point to running rich perhaps.....small amount of carbon but biscuit colour with a bit of wet.......(oil)

I will just add i have run it in a bin on idle and at different revs but it has idled alot so not normal use...would this cause the incomplete burn of all the oil and cause this wet as the oil that has not burnt must go somewhere??
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Re: Spark plug condition

Post by enzo200500 » 16 Nov 2017, 15:20

You really need to run the engine under proper loading conditions to get a true idea of mixtures etc.

Look up plug chopping on motorcycles.

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Re: Spark plug condition

Post by Martin » 16 Nov 2017, 15:21

A quick look at those images, i'd say the oil mixture is too high - too much unburned, it looks like you have a large gap on the plugs too :LMT
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Re: Spark plug condition

Post by mattswan2512 » 16 Nov 2017, 15:29

I am running 100:1 on the oil mixture but i think its because its been idling for a long time. I dont have a spark tester and trying to earth it out on the body was a pain in the arse so i shall be replacing them shortly. The side electrode i would agree has some wear increasing the gap but as i say i did not check if the spark is jumping early as getting it to stay was a pain.
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Re: Spark plug condition

Post by Martin » 16 Nov 2017, 15:47

What's the gap set at matt ?
It looks huge, prob just an image thing on the comps..
A quick look online and i'm guessing its a 40thou gap (1mm) which is a large gap anyway so perhaps i'm talking nonsense.
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Re: Spark plug condition

Post by Paul B » 16 Nov 2017, 15:53

100:1 could be part of the problem, what is the recommend mix? That could be way too much oil, Also are you using marine grade 2 stroke oil or just a generic one
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Re: Spark plug condition

Post by mattswan2512 » 16 Nov 2017, 16:31

Paul 100:1 is a very low ratio mate so 100 parts of fuel to 1 part oil so 50:1 is a richer mix mate. Yes marine grade oil mate

100:1 is recommended for leisure 50:1 for commercial
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Re: Spark plug condition

Post by Paul B » 16 Nov 2017, 16:49

mattswan2512 wrote:Paul 100:1 is a very low ratio mate so 100 parts of fuel to 1 part oil so 50:1 is a richer mix mate. Yes marine grade oil mate

100:1 is recommended for leisure 50:1 for commercial
Sorry mate I had a brain fart and getting it wrong way round :lol:
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Re: Spark plug condition

Post by mattswan2512 » 16 Nov 2017, 17:02

No worries mate i get em all the time lol. I used to race 2 stroke karts for a good few years so i like to think i know how to pre mix by now lol

Some people say run 75:1 and i have but you can smell how much richer the mixture is so 100:1 for me now. Fingers crossed some new plugs and another carb rebuild will do the job. Hopefully out this weekend or perhaps tomoz to test.

Ive not put a feeler guage on them and yes should be 1mm but the later plugs they recomment 1.5mm as they have a V ridge in them to keep the spark controlled but ill replace like for like as thats what the book says.....

Seen a full service kit with impeller for £50 including leg oil impeller spark plugs and grease for my engine so tgats a bargain and will be winging its way to me soon enough.
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Re: Spark plug condition

Post by Martin » 16 Nov 2017, 17:13

Matt, silly question time...
You do realise you can adjust the spark plug gap ????
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