How to rig up a simple homade spark tester?

[Hoyt79]

How do you do this and what type of wire do you use...do the plugs need to be attached to the plug wires while doing this?

 

[wifisher]

Re: How to rig up a simple homade spark tester?

There are many ways it has been done. place the plug against the head, and use it is probably the most common. It will NOT, however, diagnose a weak spark, only a no spark. Some people use a screwdriver jammed in the wire and gap it a ways off of the head. I'm sure you could make any number of different fixtures to do it, but have to ask why not spend the $6 on the one they sell almost everywhere?

Seems to me, that it is cheaper and easier to use the product that is available and known to work.

 

[Cofe]

Re: How to rig up a simple homade spark tester?

Find a old automotive distributor cap. Fabricate a metal disk that will center inside the cap and leave 7/16 of a inch between each cylinder post and the metal disk. Drill a hole in the center of the disk and the center of the distributor cap. Bolt the disk in place and attach a ground wire to the outside center post bolt.

Hook up the plug wires from your motor to the distributor cap. Attach the center ground wire to the power head. You can check up to eight cylinders at the same time and have a night time light show.....

 

[jeffersondodson561]

Re: How to rig up a simple homade spark tester?

I use the plug against the block, OMC has one of the strongest spark their is, notorious for eating up plugs where as a Yamaha has one of the weakest spark to see. The fact is with a proper air/fuel mixture it is easier for the spark to jump the gap because of the conductivity of the fuel;KV meters work on this concept. But people like using spark testers and their is nothing wrong with that.

 

[boobie]

Re: How to rig up a simple homade spark tester?

I can buy an open air gap adjustable spark tester at Advanced Auto for $8.00. Sure beats making one.

 

[HighTrim]

Re: How to rig up a simple homade spark tester?

As stated, checking spark against the block is not adequate. It MUST jump an open air gap, gap dependent on model, to satisfactorily run while under load on the water. I have seen many motors that were apparently sparking, yet were not firing on all cylinders at the lake. These people either tested with the plug against the block technique, or those bulb type testers.

I use the cheap $5 tester for my old single cylinder motors, but have found that the homemade, multi cylinder tester is quicker and easier for multi cylinder motors.

 

[beagleboy]

Re: How to rig up a simple homade spark tester?

I can buy an open air gap adjustable spark tester at Advanced Auto for $8.00. Sure beats making one.

Cautionary notefor checking spark CDI systems. Make sure plug wires if not hooked to spark plug are grounded. If not you have a very good chance of frying your CD pack.

 

[HighTrim]

Re: How to rig up a simple homade spark tester?

Cant ground the plug lead, need it hooked up to the tester, lol.

Unless you are referring to the remaining cylinders? They remain on the plugs of course.

 

[jeffersondodson561]

Re: How to rig up a simple homade spark tester?

Cautionary notefor checking spark CDI systems. Make sure plug wires if not hooked to spark plug are grounded. If not you have a very good chance of frying your CD pack.

A lot of manufactures ground out the triggers to engage the emergency stop circuit so the voltage from the stator is always present in the capacitor, and being a capacitor you can never put more voltage into it than given...it would be more devestating to ground out 150 volts rather than 3-7 volts.

 

[ronsealdeath]

Re: How to rig up a simple homade spark tester?

I took 2 pieces of wood, about half inch by an inch and joined with a small piece of ply. I put a nail through each end of the wood blocks so points of the nails were just under half an inch apart. So you have a u shaped wooden structure holding 2 nails facing each other with a gap. Hook a wire and crocodile clip to the end of each nail (not the end where the spark will jump!)
Hook one wire to the block and the other end to the end of the HT lead. Hook the other HT lead to the block also or leave the plug in.
Crank and get someone to tell if you see a spark (or jump the solenoid so you can see what is going on at the back of the powerhead). If it jumps a gap of half an inch (7/16 I think is the figure?) or so then your sweet, apparently. I'm no expert, this is just what Joe Reeves advocates!
I had to lay my little tester on a wooden block as it kept arcing on the powerhead. It took me 2 mins to make and works really well.
Cheers