I have been running about 60miles jetting in, and run in my rebuilt 550 engine.. with some tuning like jemco's and porting.. (no cylinder port change, just crankcase and intake channels..
i took the the sparks plugs up, to see where i was in jetting.. and it looked a bit different compared my old setup..?
the spark plug is only 3/4 colured at the base ring... the 1/4 non colured area is away from the exhaust.. what causes this difference?
strange spark plug colouring..normal?
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Allan k
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strange spark plug colouring..normal?
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2-strokes are full of speed,
4-strokes are full of parts!
4-strokes are full of parts!
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Alan H
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Re: strange spark plug colouring..normal?
That looks like the mixture isn't far off but not enough of it.
Is that carb opening up the same as the other two? Not the bar that lifts the slide, the actual slide and needle.
Can't see the scavenging cleaning half of the plug and not the other half. Very odd.
Is that carb opening up the same as the other two? Not the bar that lifts the slide, the actual slide and needle.
Can't see the scavenging cleaning half of the plug and not the other half. Very odd.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
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tz375
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Re: strange spark plug colouring..normal?
That clean section is because the mixture is so rich, that part of the plug is staying too cool to build any color.
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ja-moo
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Re: strange spark plug colouring..normal?
There is too much turbulence to read correct jetting from that part of the plug. The mixture reading is where the ceramic meets the metal at the very bottom of the plug.There should be a ring of about this color on the ceramic right it meets the metal, 1 to 2mm wide. This can only be read with a very bright light and a 10x magnifier, or cutting the plug apart.
What it does show, from all excessive deposits in that many miles, is it is too rich, as was said
What it does show, from all excessive deposits in that many miles, is it is too rich, as was said
Visiting from the "K" camp...........
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Allan k
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Re: strange spark plug colouring..normal?
thanks for your input..
the plug is identical in all 3 cylinders..
i have only done very short bursts of power, and the oil pump had been set way too high, to get air out of the cci system.. that might have had an influence on the plug colouring.. and only 60 miles (100km) is maybe to early to tell?
when i'm off the throttle (not accelerating) and maintaining a steady speed 30-50mph the engine 4-strokes a bit.. is this sign of the rich setting?
the plug is identical in all 3 cylinders..
i have only done very short bursts of power, and the oil pump had been set way too high, to get air out of the cci system.. that might have had an influence on the plug colouring.. and only 60 miles (100km) is maybe to early to tell?
when i'm off the throttle (not accelerating) and maintaining a steady speed 30-50mph the engine 4-strokes a bit.. is this sign of the rich setting?
2-strokes are full of speed,
4-strokes are full of parts!
4-strokes are full of parts!
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tz375
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Re: strange spark plug colouring..normal?
Probably, but it could also be a lean surge. Try lifting the needles one clip position or richen the idle screw by 1/4 turn and see if that fixes it and if it makes it worse, go 1/4 turn the other way.
Plugs are very hard to read unless you have it WOT under load. My plugs look rich which is marginally true at 0-1/4 throttle where it has spent most time on the street, but at WOT it is lean and unless I do a proper chop I can't see that.
Plugs are very hard to read unless you have it WOT under load. My plugs look rich which is marginally true at 0-1/4 throttle where it has spent most time on the street, but at WOT it is lean and unless I do a proper chop I can't see that.
