Ignition coil testing confusion

[timbaux]

i am trying to determine if one of my coils is bad on my 85 gs550e.... the manual says check the low side of the coils and should have 3-5 ohms... that checks out fine.

On the secondary side, from spark plug cap to spark plug cap one each coil, supposed to have 31-33 ohms... i must be doing something wrong. i get no reading at all.

I am using a Klein digital meter with ohm/resistance capability, and the manual does not call for a ohm range selection.

Just really confused, any help appreciated.

[hannibal]

I'm pretty sure it's 31k to 33k. If you're seeing an open reading (huge resistance), the usual advice is to remove the plug caps, trim a bit off the end of the plug wire, and reinstall the caps.

[Steve]

At least make sure your meter is in the correct range, unless it's an auto-ranging meter.

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[timbaux]

At least make sure your meter is in the correct range, unless it's an auto-ranging meter.

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its auto-ranging. i pulled the caps off, checked from lead to lead, and i get no reading.

[fbody_mike]

Since you got the caps off, check them too, should be between 5-10k each. What about the other coil, can you read the resistance on the secondary side, just to confirm your meter is working.

[timbaux]

Since you got the caps off, check them too, should be between 5-10k each. What about the other coil, can you read the resistance on the secondary side, just to confirm your meter is working.

the meter works.. it works on the low side..4.6 ohms about, on both sides.

[tom203]

Borrow a cheap meter and see if you still get no reading wire to wire on secondary using 200k scale.

[timbaux]

Borrow a cheap meter and see if you still get no reading wire to wire on secondary using 200k scale.

I had to rush to find the problem, had a spare coil for cylinders 2-3 and it works, that was the problem. I just fixed it two hours ago. So far, so good.

I wanted to try to get the ohmmeter to work, so i could test the way the manual suggests.

I do a lot of small engine repairs, have never put together a dohc 4 cylinder, but about to attempt it. In small engine repair, the spark tester i use is really a fast way of finding the problem. I am going to find a similar one for motorcycles and buy it. The one i have doesnt fit on the spark plug for a bike.

Thanks for responding, i am going to use the old style multimeter i have somewhere in the house, with the needle pointer and see if it works. Thanks all of you who have responded.

[tobaccorancher]

I am going through the electrical system on my recently acquired 1979 GS750 and am now going through the ignition system. The bike has one new coil and the other coil is original. I removed the spark plug caps and the original coil checks out good. But when I measured the caps I get an open circuit on one and 600 KOhm on the other. Which brings me to the question. The secondaries on these coils go to two plugs. So, when you develop a problem on one spark plug cap, it seems to me that you have a problem on both of the plugs on that coil. So, one corroded or loose cap, and you lose two cylinders. Am I correct? Check those spark plug caps!!!!

[Gorminrider]

yes. need both good.
I went through a "cap " phase myself on a bike this winter. The old Suzuki caps can be a pain with their teeny bits of metal and new ones are so nice and not super expensive either.... but get very near the original length and angle for the replacements and also not to be trimming too much off the high tension leads. I had the idea that what fit one suzuki would fit another bike but luckily noticed 'tis not so...

[tobaccorancher]

Thanks. Yes, bought new caps and plugs in a kit off the online bidding site, around $40 for all. The new caps are so much better than the originals, and they have the correct resistance. I tried to clean my old ones just to see if it was possible, and I would say the answer is probably no. The resistors were corroded, and I don't know what I would have used to clean them without making them deteriorate quickly when re-used. Also, there were two tiny copper disks on mine on both sides of the resistor that were tarnished, and they would have been very difficult to restore. I only cut the leads back around 1/4 inch, enough to see good wire. The wire was surprisingly in great shape after all of these years.

Quick question if anybody knows...do I lubricate the outside of the wires with silicone to help slide the wires securely into the new caps? Or, maybe some other lubricant? Also, was thinking about putting a layer of heat shrink over the old wires to try to compensate for 40 years of aging....good idea, or ridiculous?

Thanks,
Andy

[Grimly]

I tried all them back 30 years ago when the bikes were out around the clock in all weathers. Even went so far as to sleeve each HT lead in garden hose and seal up the coils as far as possible with varnish, after drying them in an over very slowly for hours. It all kind of worked, but wasn't perfect. That damned motorway spray gets into the slightest gap.
I found the only long-term solution was using Honda MT08 coils and new leads, caps, and the only sleeving on them is to protect against mechanical abrasion.
People on forums have relatively recently found MT08 coils, but I got a set from a CBR1000 fresh write-off when they were only a year old. I'm still using that pair, but now have a boxful of replacements acquired in the past couple of years, just in case I need them.
The MT08 coil matches the primary resistance requirement for Suzuki and has easily replaceable HT leads. Altogether, it's a better coil and and is easily found on a lot of Hondas, but the best donor is the Gold Wing 1500 - you get three of them for as little as $25 if you keep your eyes open on the Bay of E.

[Gorminrider]

quick question if anybody knows...do I lubricate the outside of the wires with silicone to help slide the wires securely into the new caps? Or, maybe some other lubricant? Also, was thinking about putting a layer of heat shrink over the old wires to try to compensate for 40 years of aging....good idea, or ridiculous?

spit is my goto...but if no go a touch of vaseline maybe. even motor oil. neither would hurt them as far as i know.

Heatshrink is an ok idea-not something I've ever done as a precaution nor needed too but I'll opine: It's not as flexible as the wires alone.Might look ugly if it creases AND it'll make the boots even harder to get on. (though vaseline might do it) AND you'll likely want two sizes-one for the wire and one to go over the boot and the heat-shrink-covered wire. ...It's starting to sound baroque and my brain hurts.

but it'd sure be a good idea at noteable chafe points and if you do it show pictures!