When using a spark plug tester on a 2004 1500 classic, what's a good tester gap distance to use when cranking over the engine? I think I've seen someone mention using a 3/8" gap, but if I set the gap to like 1/2" and get a good spark would that be an indication the coils are good? And what gap distance to get a decent spark is sign of a bad coil?
i thought the way to test the ignition system was to check the resistance between certain points. ground and plug, plug and plug... over time, the resistance gets higher and higher, and once out of spec, it's considered weak. anyhows, on my bike, my plugs are supposed to be gapped to .035". i don't think that was your question so i'll just shut up now.
I am still learning, this spark plug tester tool is suppose to go between the spark plug and wire, you can leave the spark plug in the cylinder, just pull off the spark plug wire and attach the wire end to this gap tool tester, then clip the tester tools alligator clip to a ground place on the bike. The gap on the tester can be adjusted to determine the spark strength when you crank over the engine. It's this gap distance on the tester that I wanted to know how far I should set it. I heard it can be purchased at any auto parts stores.
Start with the recommended gap of your plugs, then you can go wider to see if you still get spark.
The idea of the tester is:
1. You can get a good look at the spark to ensure that it is not only there, but fat and blue.
2. It provides a load to your ignition system. Using the old screwdriver or sparkplug method can be hazardess to your ignitor as a good load may not happen consistently.
3. You can open up the gap to detect coils that may fail when the firing voltage goes up. Do not get carried away with the big gaps though as you may get a mis-fire which again is a no-no. Free air firing voltage may be, say, 8000v whereas combustion chamber voltage may be, say, 14,000v. This tool enables you to duplicate that.
4. It is a hands free operation allowing one to sleep while making the test instead of having high voltage flow through your body and in turn, waking you up!
5. This tool checks everything at once...if you have a bad wire, it will show up.
As an add, if I had a dollar for every person I have helped over the years that swore up and down they had no spark, but when the tool is installed the spark magically appears, I would have a brand new Ultra Classic in my garage!
I just pulled off my spark plug wire and notice that the end of the spark plug has no screw-on cap, just the threads are showing, so I went into my fresh box of DPR5EA-9 and looked at a new plug and no cap also just the threads showing, how come there's no caps? Shouldn't I have caps on my plugs? Maybe that's why my spark plug wire isn't seated firmly on the right-rear cylinder side.
That unit seems a little pricey and is for coil-on-plug set ups. I am not sure if the end is the same. Your bike has the threaded spark plug end instead of the conventional end.
That is probably correct. You have two choices:
1. Just insert the tester into your plug boot as is. The spark will have no trouble jumping the tiny gap there.
2. I made an adapter with a screw of the correct size and an old spark plug wire clip soldered to it. That way I can do both styles.
This one can be had for around the $10 mark at most Princess Auto, Canadian tire, etc.
Oh, maybe that Coil-On Spark Plug Tester has the wrong end and not the threaded end like my NGK spark plugs, ok, now to improvise, you made an adapter to fit so maybe I can find the proper size screw the size of the spark plug end, and solder it onto the end of this new Tester I'm getting, I paid for it on ebay so it's a done deal now, all I can do now is modify it like you did.