What is the correct spark colour?

[smsscuba]

I removed all three sparkplugs from my Johnson 35hp this afternoon and manually cranked the engine.All three cylinders were producing a very bright white coloured spark that looked more like a flash than a spark.It seemed like a good strong spark.

What worries me however is that searching through this forum and comparing it with my 3.5hp, which produces blue lightning like spark .Should I worry, bearing in mind I have removed the coils and power pack and cleaned it all, especially the earths.

Am I just being paranoid?

 

[oldcatamount]

Re: What is the correct spark colour?

How are you testing the spark? Are you using a spark tester or are you using the plugs themselves?

 

[smsscuba]

Re: What is the correct spark colour?

I was using the plugs grounded against the body.I don`t have a tester.All the plugs I have tried (bikes,cars,lawnmowers and outboards)in the past have produced a spark with a hint of blue.

 

[oldcatamount]

Re: What is the correct spark colour?

That's not really an accurate way to test the ignition, but, if they are all the same color, I'd say you're ok. Is your motor running alright?

 

[smsscuba]

Re: What is the correct spark colour?

I have not fired her up as of yet, only got her a couple of days ago.The previous owner said she performed well (told me it will run rings around the new Honda 40hp 4 stroke it was replaced with).

I was just curious of the white coloured spark.

 

[Joe Reeves]

Re: What is the correct spark colour?

Spark should be a strong blue lightning like flame that will jump a 7/16" gap.... a real SNAP! You can insert a philips screwdriver into the spark plug wire terninal, a screwdriver that will fit inside of that coiled wire terminal, then hold the shank of the screwdriver an approximate 7/16" or 1/2" away from the powerhead..... that will give you a good enough spark test. Using the spark plugs is a waste of time.

You could also build the following.

(Spark Tester - Home Made)
(J. Reeves)

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:


..........X1..........X2

.................X..(grd)

..........X3..........X4

 

[smsscuba]

Re: What is the correct spark colour?

Much appreciated.I will attempt to build one this coming weekend.

 

[smsscuba]

Re: What is the correct spark colour?

Earlier on this evening I attatched a wire to each plug lead in turn and cranked the motor.I got a nice electric blue spark that would even jump a
6mm gap with a sharp cracking sound (not to mention that I accidently became the earth at one point and still have pins and needles in my left arm!)

It is strange that it produced only a white "spark" when the plug was used to check spark and by using a wire to ground it makes a healthy blue lightning like spark.

I see now why I was advised to not check spark using the spark plug to ground method.Thanks to all, I may now sleep at peace tonight.

 

[boobie]

Re: What is the correct spark colour?

Model # ?? . May have some info for you.

 

[smsscuba]

Re: What is the correct spark colour?

any info would be a help.The model is BJ35ARLECR.