Home made spark tester

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mables

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Sep 17, 2010
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Just wondering if anyone has pictures and a basic list of hardware needed to make a homemade spark tester.

I know I have seen them at auto parts stores for around 10bucks but they seem simple enough that you could make them yourself or if anyone has a pic of theirs they can upload with a description that would be helpful.

I don't have a use for one atm but they are pretty much essential in determining spark quality, and I have an old 76 kz650 that I need to start working on again and I always suspected weak spark but it ran just not at what it should, anyways any responses will be appreciated.
 
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seahorse5

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Re: Home made spark tester

Take a standard sparkplug and twist and break off the ground electrode. Use a small hose clamp to fasten a ground wire to the metal shell by the hex, then put an alligator clip on the other end of the wire.

clamp the alligator clip to a ground and the push the plug wire onto the sparkplug. If the motor has sufficient spart to start, it will jump the opening from the center electrode to the inside of the metal shell.
 
5150abf

5150abf

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Re: Home made spark tester

I have made one form a peice of cardboard, some duct tape, a screw driver and a bolt.

Stuck the bolt in the plug lead and taped it 7/8'' from the screw driver that was grounded to the engine, it was pretty ugly but it worked.
 
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mables

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Re: Home made spark tester

That is exactly the ingenuity I was looking for thanks guys.
 
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wilde1j

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Re: Home made spark tester

I made one years ago for testing four holes at once. I used a 4x4" piece of 1/4" lucite, five threaded standoffs, four sharpened large finishing nails, four spark plug leads and a ground lead with an alligator clip for the center post. I made it with a hook so I could hang it. The nails went thru the four posts and had set screws to hold them in position ... the air gap could be adjusted from 0 to about 3/4", and was set to 7/16", since that's the most common for CDI motors. If interested, I could find this tester and post a picture. The nice thing is that it allows seeing the spark for each cylinder and only takes a few seconds to set up. Been using it for over 35 years.
 
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mables

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Re: Home made spark tester

If the picture wouldn't be to much trouble then yeah I'd love to see it, I like the idea of one being adjustable easily as i work on a range of projects and not all with cdi I was thinking of doing the v8 dist cap and getting different sized tins for the middle washer in order for it to be adjustable but the setup you have would be much easier to do on the fly.
 
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wilde1j

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Re: Home made spark tester

Not very pretty, but has worked for a lot of years. Alligator clip wire goes from brass colored bracket to a good ground.
 

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boobie

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Re: Home made spark tester

Those are fine for certain applications ( I have two of them ) but for some trouble shooting procedures on other mtrs you have to increase the gap which you can't do on these. Your best bet would be to go to Advanced Auto or some other parts houses and get an adjustable gap one. They sell for around $10.
 
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mables

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Re: Home made spark tester

Well i think i have a plan for one of my own, i'm going to borrow from the distributor idea and use something similiar of jim's design im going to put a round plate on the dist cap just like the one shown but smaller and then put a bracket with about an ince bolt that way i can adjust the distance between the plug pickup on the outside part of the cap and ground, I'll post pictures as soon as i have materials and time.
 
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daselbee

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Jan 20, 2009
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Re: Home made spark tester

tashasdaddy said:
this is all we use in my shop. for the cost, i'm not wasting my time making one.

http://cgi.ebay.com/ebaymotors/IGNI...Z370437535806QQptZMotorsQ5fAutomotiveQ5fTools
Click to expand...

That's a real nice unit there TD. Looks like it has a substantial ground wire and clip. I am going to buy a couple of those. Thanks!

EDIT: One other thing...does this unit have a jamb nut on it to lock the adjuster screw in place at the desired gap? Or can you add a jamb nut?
 
tashasdaddy

tashasdaddy

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Re: Home made spark tester

you can add a jamb nut. there is plenty of room for adjustment, perfect for our purposes.
 
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ronsealdeath

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Aug 11, 2010
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97
Re: Home made spark tester

I'm in the UK so had trouble getting one 'off the shelf'.

I had trouble getting a spark tester but Briggs and Stratton do one which you can get on ebay for ?12. This seemed like a lot to me so I bought some crocodile clip ended leads for a couple of quid and used two nails through a bit of wood, bent to give an 11 or 12mm gap.

I then used the crocodile clips to attach one nail to the HT lead and the other nail to earth on the engine block. Removed the other HT lead and earthed that too.

Make sure the tester is away from any earth points and crank it. Really easy to make and it did work. Better than spending ?12 plus delivery for something you will use on the odd occassion.
Cheers
 
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