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Ignition coil replacements

U

Un4Scene

Forum Newbie
Hello all. I'm fixing up a 1986 GS400S (North American; known as the GSX400S to the rest of the world). It's one of these, including the original red/black/white paint: https://www.motorcyclespecs.co.za/model/suzu/suzuki_gs400s 85.htm

The bike sat with a spun bearing for about 15 years, so it needs a full rebuild. I've got it about 75% of the way done, but I've run in to a problem with the ignition coils. The only replacements I've been able to find cost about $200 each, and that seems pretty preposterous. I'm not doing a full resto or anything... just trying to get it back on the road, and I already had to pay some ridiculous prices for all the bearings and such. Some jack-ass ripped the plug leads out of the original coils, so they've gotta be replaced.

The problem is that these coils seem to be a rather unusual combination of parts... they are single-output coils (one coil per spark plug), they have a marked '+' and '-' spade terminal, and they need to be in the 3 to 5 ohm range for the transistorized ignition (at 12 volts). They have an 80mm mounting distance, but I can fab up a mount if I can find something that fits the rest of the spec's.
For reference, the original p/n is: 3341044510, superceded by 3341044X50

Thus far, the only universal coils I've found that have the correct connections have not listed the ohms, and they've had unresponsive sellers.

Does anyone have recommendations for something I could use in place of the OEM coils? Something from a different bike, or a universal coil... I'm not picky - I just wanna get it working.

Ideally, it'd be something available in the US... This bike is apparently very rare in North America, and pretty common in Europe and Asia, but I've had numerous problems with companies being unable to ship products in to the US recently.

Thanks in advance.
 

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Just my opinion, put your coils back together. They originally had the wires plugged in then glued in place. Clean the holes out good, plug the wires back on to the little pin, then glue the wires back in with some kind of good glue. I'd use Shoe Goo, seems like silicone but stronger... As always, just my opinion.
 
Agree, but replace the HT leads. 7mm copper core wire. The previous owner did you a favor with pulling out the wires, I just hope the spike is still there in the coil.
 
Katana1074 said:
could you use more modern coils?, most suzuki coils fall into the 3 to 5 ohms range....

https://www.ebay.co.uk/itm/336402855817?fits=UKM_Make:Suzuki&_skw=suzuki+3ohm+coil&itmmeta=01KRDHMMH3E1H40N25GNE0WS8F&hash=item4e532c3789:g:d9QAAeSwwdZpc6pG&itmprp=enc:AQALAAAA0GfYFPkwiKCW4ZNSs2u11xDTso3mYtYXSB0H5o1DlWVJKgPJdryzntsXDlxbcnpwOww8uV903UYX61MeLUgmHFoMeCDND8V1vI6jNPB+xjJY1I5wu3EBxFdT5pRVOJGXDoio32y0PrteZo6w+n9gaRC0wUkPSxAWYY4ATdFh+efS5G5N+f+7a--D67UIhR1JbKyZlN0wTvWJOeWlAdi6JtuYGKHpX2lH30ZaEpCnNY1T6FZYJUkFBGHUSIpKOv+vUhLjkvFalyGVgHMzOIWuV0k=|tkp:Bk9SR-7I0rHDZw
Click to expand...
Yes, that's the kind of thing that I'm looking for. The ones in the link you provided appear to have very short spark plug leads, but something similar should work. I have been (and still am) searching for something I can use, but it's difficult to track down the required spec's on what I find - it's not like I have a repair manual for every bike out there - and there are just SO MANY different motorcycles to search through.

I've also emailed multiple sellers of ... budget ... ignition coils, but none of them have been willing to provide spec's for the coils they're selling... probably because they either don't have the spec's, or because they just don't wanna spend the time to search through them to find something that fits what I need.

The older Suzuki bikes that have points use coils with lower resistance (ohms) - too low to be suitable. As ignition systems modernized, the resistance was increased, but a lot of them switched to a true CDI ignition, or different types of systems where the coil is grounded through the mount/frame, rather than the coil being isolated as mine is - that's why mine has both '+' and '-' inputs. The negative is switched by the ignition controller. Ironically, the most modern coil-on-plug systems should, theoretically, have the correct wiring to match the old transistorized ignition systems since they're not grounded through the mount/frame, but there's no way to secure the coils to the old motors (and I don't know what kind of resistance they have, either). The transistorized ignition is one of those in-between technologies that was only used for a relatively short period of time.

From what I can tell, it seems the OEM coils for my bike were also used on many of the GS450's from about '82 to '88 (a much more common bike), so I was hoping that someone on this forum might have some experience replacing them with something else.
 
Incidentally, I did find a seller (Interlight) that listed some of the afore-mentioned budget coils as a direct replacement for my specific part number, and I ordered them. When I received them, though, I found that they only have a single '+' input terminal, so they are not usable with this ignition system. When communicating with the company for a refund, they told me that the incorrect part-number information on their website was provided by the Chinese manufacturer. Sooo... I'm a little wary about trusting something like that again, if the seller isn't willing to verify it for me before hand.
 

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May be a help as maybe you could broaden your search. There are motorcycle parts houses where you can look up your part, click a button, and they tell you which other models use that same part... I can never remember which ones they are...... I'm still thinking about fix'in your old ones, some would call it rigg'in but I call it making it work as new.
 
Un4Scene said:
Yes, that's the kind of thing that I'm looking for. The ones in the link you provided appear to have very short spark plug leads, but something similar should work. I have been (and still am) searching for something I can use, but it's difficult to track down the required spec's on what I find - it's not like I have a repair manual for every bike out there - and there are just SO MANY different motorcycles to search through.

I've also emailed multiple sellers of ... budget ... ignition coils, but none of them have been willing to provide spec's for the coils they're selling... probably because they either don't have the spec's, or because they just don't wanna spend the time to search through them to find something that fits what I need.

The older Suzuki bikes that have points use coils with lower resistance (ohms) - too low to be suitable. As ignition systems modernized, the resistance was increased, but a lot of them switched to a true CDI ignition, or different types of systems where the coil is grounded through the mount/frame, rather than the coil being isolated as mine is - that's why mine has both '+' and '-' inputs. The negative is switched by the ignition controller. Ironically, the most modern coil-on-plug systems should, theoretically, have the correct wiring to match the old transistorized ignition systems since they're not grounded through the mount/frame, but there's no way to secure the coils to the old motors (and I don't know what kind of resistance they have, either). The transistorized ignition is one of those in-between technologies that was only used for a relatively short period of time.

From what I can tell, it seems the OEM coils for my bike were also used on many of the GS450's from about '82 to '88 (a much more common bike), so I was hoping that someone on this forum might have some experience replacing them with something else.
Click to expand...

With later year electronic ignition systems, resistance typically went down in the coils, not up. With a low resistance coil, you can add a ballast resistor if you have to, to increase resistance. And common road-going bikes don't use a CDI system, they use a transistorized ignition system. GS & KZ bikes, for example, use an "ignitor" to fire the coils.

These are not cheap, but just an idea of what's out there...

www.mikesxs.net

Coil - Ignition - 3.3 Ohm - Single Output - XS Performance

Color/Finish: Green Material: Plastic Fits: Yamaha XS650, RD250, others (see fitment) OEM Ref: 254-82310-60-00
www.mikesxs.net www.mikesxs.net
 
rphillips said:
May be a help as maybe you could broaden your search. There are motorcycle parts houses where you can look up your part, click a button, and they tell you which other models use that same part... I can never remember which ones they are...... I'm still thinking about fix'in your old ones, some would call it rigg'in but I call it making it work as new.
Click to expand...
That's why I mentioned the '82-'88 GS450 in the previous post. It's the only other model I know of that uses the same coils.

There is nothing in the hole to attach the plug lead to. The only way that even might work is if I broke apart the housing for the coil, and attached a new wire to the actual coils inside, and then fed that through the hole... which wouldn't even possible if it's potted, as a lot of Suzuki electronics are. I don't know if it is or not. Regardless, breaking apart the housing would probably result in compromising the insulation for the coil (it'd likely arc to the coil bracket or bike frame) rendering it unusable. I appreciate the suggestion, but I just don't think it's feasible in this case.
 
Un4Scene said:
Yes, that's the kind of thing that I'm looking for. The ones in the link you provided appear to have very short spark plug leads, but something similar should work. I have been (and still am) searching for something I can use, but it's difficult to track down the required spec's on what I find - it's not like I have a repair manual for every bike out there - and there are just SO MANY different motorcycles to search through.

I've also emailed multiple sellers of ... budget ... ignition coils, but none of them have been willing to provide spec's for the coils they're selling... probably because they either don't have the spec's, or because they just don't wanna spend the time to search through them to find something that fits what I need.

The older Suzuki bikes that have points use coils with lower resistance (ohms) - too low to be suitable. As ignition systems modernized, the resistance was increased, but a lot of them switched to a true CDI ignition, or different types of systems where the coil is grounded through the mount/frame, rather than the coil being isolated as mine is - that's why mine has both '+' and '-' inputs. The negative is switched by the ignition controller. Ironically, the most modern coil-on-plug systems should, theoretically, have the correct wiring to match the old transistorized ignition systems since they're not grounded through the mount/frame, but there's no way to secure the coils to the old motors (and I don't know what kind of resistance they have, either). The transistorized ignition is one of those in-between technologies that was only used for a relatively short period of time.

From what I can tell, it seems the OEM coils for my bike were also used on many of the GS450's from about '82 to '88 (a much more common bike), so I was hoping that someone on this forum might have some experience replacing them with something else.
Click to expand...
Pretty much any single suzuki coil from 1977-2006 would work as most are 3 to 5 ohms , I have bandit 2006 1200 coils on my 88 gsx1100ef,

most of the specs for suzuki coils can be found easily...

So basically you need 3 -5 ohms with + and - terminals with a fairly long HT lead...

GS500E coils would be a good swap....


or suzuki vx800 - 3-6 ohm coils
 
Last edited:
Nessism said:
With later year electronic ignition systems, resistance typically went down in the coils, not up. With a low resistance coil, you can add a ballast resistor if you have to, to increase resistance. And common road-going bikes don't use a CDI system, they use a transistorized ignition system. GS & KZ bikes, for example, use an "ignitor" to fire the coils.

These are not cheap, but just an idea of what's out there...

www.mikesxs.net

Coil - Ignition - 3.3 Ohm - Single Output - XS Performance

Color/Finish: Green Material: Plastic Fits: Yamaha XS650, RD250, others (see fitment) OEM Ref: 254-82310-60-00
www.mikesxs.net www.mikesxs.net
Click to expand...
I think there's some miscommunication and/or misunderstanding here. I didn't mean to imply that CDI is what's used on modern bikes - just that it was commonly used on the earlier models that eliminated the old ignition points system. Most modern engines use an inductive discharge system (IDI) rather than capacitative discharge (CDI) or transistorized ignition systems... although, I suppose that depends on how you define a 'transistorized' system, which is, admittedly, kind of a grey area. lol

I hadn't thought of adding a ballast resistor... I might be able to make that work... I'ma have to do some figuring on that prospect.

The coil you linked might be usable for my bike... 3.3 ohms is definitely on the low side, but I might be able to make it work if I can get more info about it. You may notice that it says it's for "1970 & up"... I guarantee you that coil is intended to be used for a points system. That's why the resistance is relatively low. IIRC, the stock coils for my bike were supposed to be 4.3 ohms, though I'm not 100% certain about that. It's been difficult to find information about this machine. /sigh

Thanks for the input.
 
Katana1074 said:
Pretty much any single suzuki coil from 1977-2006 would work as most are 3 to 5 ohms , I have bandit 2006 1200 coils on my 88 gsx1100ef,

most of the specs for suzuki coils can be found easily...

So basically you need 3 -5 ohms with + and - terminals with a fairly long HT lead...

GS500E coils would be a good swap....


or suzuki vx800 - 3-6 ohm coils
Click to expand...
You have an easy source for ignition coil spec's? PLEASE share that with me! That would be extremely useful!
 
Taking a chance of ruining a coil you're planning on throwing away anyhow. Drill small hole, appx. 1/4" deep where your spike is broke off. find small or tiny nail to fit the hole & make a new spike. I doubt the plug wire will never know if spike is factory or a replacement... I do realize most never try this kind of stuff, but I love it..
 
rphillips said:
Taking a chance of ruining a coil you're planning on throwing away anyhow. Drill small hole, appx. 1/4" deep where your spike is broke off. find small or tiny nail to fit the hole & make a new spike. I doubt the plug wire will never know if spike is factory or a replacement... I do realize most never try this kind of stuff, but I love it..
Click to expand...
In most cases, I'd be all about getting clever with a repair like this... I like the concept, for sure. lol
I'm only hesitant because I've read numerous stories that lead me to believe that the transistorized ignition control module on these bikes is rather fragile, electrically. Some of those stories involved it apparently failing because of problems with the coils. I don't know details of the what or how it happened, but it appears to be a thing that I should be worried about. If that box gets damaged, then the coils will be the least of my ignition woes, since the box is NLA, and nearly impossible to repair. If I run out of other options, I'll consider it, but it's not something I'm eager to experiment with, given the potential consequences.
 
Katana1074 said:
https://gsarchive.bwringer.com/

https://www.carlsalter.com/suzuki-service-manuals.asp

coils specs is gleaned from the workshop manuals....
Click to expand...
The GS Archive is one that I've looked at before. The other list is new to me. Thank you for the link - lots of information there!


As I said above, it's been difficult to find info for this bike. That's not due to a lack of effort, I assure you. As far as I can tell, there is no repair manual for it. The one that seems like it should cover this bike (GS400-450 '77 - '87) is listed on the GS Archive page, and I have a hard copy of it that I ordered after buying the bike. Unfortunately, that book only covers the GS400 up to '83 (IIRC), as the model was completely changed beginning in '84. There are some similarities between the '86 GS400 and the equivalent GS450, but there are a lot of differences as well (the GS450 is a cruiser, while the GS400 is not). It gets even more complicated when you discover that Suzuki had multiple 400cc motors in production at the same time, and they have absolutely nothing in common. Mine is a parallel twin with DOHC and 4 valves per cylinder. There's an entirely different 400cc parallel twin with SOHC and 2 valves per cylinder, and another 400cc that's an inline 4-cylinder.
So, yeah. It's ... a mess... trying to find information specific to my bike. lol

That aside, info for other Suzuki's will be useful in trying to find a coil from a different bike that I can use on mine, so thank you for the links.
 
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