1980 GS400e Manual Spark Advance / Electronic Ignition

[jharvey]

Greetings all,

So here's the situation, I've been riding old faithful here for the last 42 years (original owner), and had the points replaced last year. This year, as I was talking to my mechanic about some upcoming annual maintenance, I mentioned a minor symptom from the last five or more years, that occasionally (maybe once every 4 or 5 rides), when I roll up to a stop at an intersection and roll off the throttle, the engine won't slow down unless I engage the clutch a bit and 'drag' it back down to idle.

He told me this was a common thing with older bikes, specifically weakening springs on the mechanical spark advance, which I should replace. (Part number 5 on this page...
https://www.partzilla.com/catalog/su...gnal-generator)

Naturally, that part isn't available any more, and the ones I see on eBay look like they were pulled out of a swamp (and some don't even have the springs attached any more), so I'm wondering if anyone knows of some little-known source I might not be aware of, beyond the RevZillas, GPBikes, etc. or even if the springs themselves are fairly standard and something I could get separately.

I've also been advised over the years that an electronic ignition would simplify things (but haven't bothered when I look at the price differences). I'd go for that option now if it would fix things, but as I understand it, even if I replaced the points, the new EI would still be using the existing spark advance, (Quote: "The Dyna S is completely housed behind the ignition cover and uses a magnetic rotor with the original spark advance, so the factory advance curve is maintained.") so I'd be no further ahead. So in this context, if anyone knows of an EI for a 1980 GS400E that would replace both points and spark advance, I'd appreciate it.

And if all that fails, are these worn springs likely to just break at some point leaving me with a non functional engine, or will I just have to keep dealing with slowing the engine down manually from time to time.

Thanks for reading through this,

[Gorminrider]

Those springs will be the same on many Suzukis ...but you will never find just the springs. Safest is to find all the bikes that use the same part number. There is usually a list of other bikes that use the same part. Even various Hondas and Kawasakis with small to medium engines will have the same springs if you can compare physically as many parts were jobbed out to Nippon-Denso, Stanley, and suchlike.

The whole thing seems a bit odd. How many km on the bike? I've never run into "fatigued advance springs" before. If I had such symptoms, ie: what sounds like a "lean" runaway, I'd suspect a vacuum petcock because I've seen them not work well when the manifold vacuum is low.... I don't see how the advance springs would cause such symptoms occasionally but I know someone who had an advance spring issue on a BMW so I'm happy to learn if it's in my future.

You could possibly retemper the springs. You could find similar in strange places or MAKE some.

However, you say you have a 1980 400E with points. This seems rare...because in Canada,when I look for parts for MY 1981 GSX400E, I tell them to look up "GS400E" but anywhere else, my bike is a GSX400E. Your link to the part diagram is a 450. I bet the advancer would fit-it would fit on my GSX too, but as above, "safest is".... I would go here https://www.cmsnl.com/suzuki-motorcycle_model13053/ and find your bike... Scroll way down down to "GSX400" I have recently seen here a gsx that used points but generally, they used electronic ignition from 1980.

[jharvey]

Gorminrider - thanks for the input, and yes, my bike was the last of the points-using examples of that line (in fact on one occasion years ago, a different mechanic had the hardest time diagnosing my rough-running engine because he -assuming it had EI like the later models he was familiar with- didn't consider the points as the potential cause, which they were). So yes, I'm just on the wrong side of the timeline for that one -probably by months- and you're just on the right side with your '81. As I remember, the GS/GSX designation depended on where on the planet it was sold, but I hadn't thought to do searches using GSX - I'll have to do another round with that. Although I've been using the Suzuki part# for searches, you never know, perhaps using GSX400E, I might find a listing in the UK or Europe, in addition to the one at CMS (see below).

As for the 400/450 connection. In 1980, Suzuki released what was essentially the same bike in Europe and North America ('79 in Japan), with the only differences being that in Europe and Canada, it was a 400cc displacement with 4 valves per cylinder (TSCC as they called it, same as your '81), while the US model was 450cc with 2 valves per cylinder (you can tell them apart by whether the cosmetic side valve plates at the top of the cylinders are round or rectangular). Apart from the obvious parts affected by those valve/displacement differences, the bike was the same, and since the US dealers (and even parts lists on some Canadian sites like FortNine) only acknowledge the 450 variant, I have been replacing parts from lists for that model for all these years. (Bike Bandit for most of those years, but I see some recent 'unpleasantness' has eliminated that option.)

For mileage? Not all that much considering the bike's 42 years old - about 70,000km (I generally only get the chance to ride on fair weather weekends). I have had to replace the petcock (it's vacuum, yes) twice so far (the current one's probably about 3-5 years old) though both those failures manifested themselves by flooding the near cylinder to the point of fouling the spark plug beyond firing.

But thanks especially for the CMS pointer - I see they have 1 ("hurry, 1 left!"), but it's almost $300 CDN before shipping, which I expect is an elevated price over the original, so I'll do some more checking as a "GSX" and know that I have a fallback. (Even if there's only 1 left, I think my odds are pretty good of there not being another old-GS buyer looking in the next couple of weeks.)

I might also ask the mechanic about the chances of a very cheap fix - WD-40. Perhaps the springs are alright but the 42-year old pivots are just gummed up enough that they're occasionally not flipping back into position. A couple of years back. I was getting ready to replace my turn signal switch because it was so stiff I was worried about breaking something inside every time I used it. Just for the hell of it, I pointed the WD-40 tube in the opening and gave a few sprays, and years later, it's still smooth as silk. Oh, if only this could be that easy and cheap to solve...

Thanks again, it's genuinely appreciated,

[Grimly]

As one who grew up with points on bikes and cars, and also had encounters with mechanical advancers wearing out, I can tell you it's a real thing, but rare enough.
I used to just nip down to the breakers yard and get an assortment of advance springs, or even buy new if they were available - they were cheap enough.
This brings me on to my own bike. For a while, I've had a suspicion the advancer on mine is a bit worn - it's not the original, it came off another engine and the cumulative mileage on it is likely at least 200K. Just because I found one of the last available, I bought a new replacement. It wasn't cheap - about €160, but it's an essential spare for when I really do need it.

[jharvey]

Grimly, would I be correct in thinking that if the strength of replacement springs didn't exactly match the stock ones, that that would not affect engine 'mapping' (to use an EI term) because the spring is merely there to (and I'm sure I'm using the wrong terms) press a lever against a cam and as long as it's doing that, that's all that matters?

Thanks,

[Gorminrider]

Interesting per the points in your GSX! You'd be the second one here in a matter of months but I've been here 10 years! It doesn't fix your advancer but I bet you could swap to the "EI" (="Ignitor",="TCI" Does NOT equal "CDI") in minutes if you happened to come across one. They are very reliable but points are ok too. Just something to keep in the back of your mind ...

You can get the real shop manuals for your "GSX" bike at BikeCliff's Website You need BOTH
GS250T-GS300L '82 Service Manual (91MB)
GSX400 Service Manual (5.2MB)

I'd goto the nearest MC scrapyard within range of Halifax first unless they are rapacious...but I've two 400s one with 65000 kilometers and no trouble with springs so you should be safe with buying the whole advance from ebay. Don't forget to shop in Europe and the UK. It'll get to you just as quick, just as good in my experience. There's even a way to translate pages.

[jharvey]

Gorminrider, Well, technically, mine's a GS without the X, but again, essentially the same. I actually bought the Clymer and actual Suzuki (250-400 '80 in my case) Service manuals a couple of years after getting the bike all those years ago - I'll have to dig them out. (When I started going to non-Suzuki-dealer mechanics, I would leave the Suzuki Service Manual with them in case they needed to look up any clearances or torque settings, though I suspected such things were fairly universal.) But I'll have to check to see if my Suzuki manual at home is GSX rather than GS, because I notice that the ignition designation in the service manual on the BikeCliff site is EI ("transistorized ignition").

Thanks for pointing out that site though, it's a gold mine - especially the international GS Parts Catalog for any time I'll be looking for OEM part numbers, I might not have to depend on the US 450cc variant listings anymore. I've even tried searching the Suzuki Japan site in the past (with the help of Google Translate) looking for that info, and wasn't at all surprised that they wouldn't have such archival information readily accessible. I tried sending them an email a few days ago in case they could send me a file or a URL specifically for the GS400E sold in Canada in 1980 - we'll see if I hear anything back, but if not,the BikeCliff site may give me all I need there. (Turns out the CMS "hurry, 1 left!" possibility I saw yesterday was the wrong part#, so I'll have to keep looking if I want to get the actual part.)

Motorcycle salvage is ... sparse to non-existent ... out here on the east coast. There used to be a motorcycle scrap dealer in NS years ago, and when he retired a local shop called "Toad's" bought all his inventory (Toad's was my mechanic shop of choice at the time), then Toad's went out of business ... twice - and with an low volume seller like the GS400, even when they were in business, parts were scarce or unavailable by that route, but I'll definitely poke around.

Thanks again,

[Gorminrider]

too bad there's no yards...you might try a Canada wide search for one. Many are happy to converse via email...I'll have a look next time in Comox at "Jack's"
hmm. I take that EZ conversion back.. you'd need this for EI....Had a look at CMNSL - note the magnets for electronic ignition So I'd go back into earlier years say the 79 ...

https://www.cmsnl.com/suzuki-gs400-1...st/FIG-23.html

governor-assembly_medium3312011410-01_cd26.jpg

the 79 suits these

GS400 1977 (B) USA (E03)
GS400 1978 (C) (E01 E02 E04 E17 E18 E21 E22 E24 E25 E30 E34 E39)
GS400 1979 (N) (E01 E02 E04 E17 E18 E21 E22 E24 E25 E30 E34 E39)
GS400E 1978 (C) (E01 E02 E04 E17 E18 E21 E22 E24 E25 E30 E34 E39
GS400E 1979 (N) (E01 E02 E04 E17 E18 E21 E22 E24 E25 E30 E34 E39
GS400X 1977 (B) USA (E03)

[jharvey]

That's the part # (33120-44011), I've been using as my guide as well - though it APPEARS to be the same part with a different part# on the later models with the EI (part # 33120-44120 here https://www.partzilla.com/catalog/su...gnal-generator). This is another one of those relatively few parts differences between the US 450ET and the Canadian 400ET in 1980 - the former presumably getting EI a year sooner, but PERHAPS using the same spark advancer under a different part number - but we wouldn't want things to be simply, right?

Curiosity... I expect it says somewhere on the site, and probably has to do with the various markets, but I can't find anything - do you know what all the "E01, E01, E17..." etc are referring to?

[Grimly]

Grimly, would I be correct in thinking that if the strength of replacement springs didn't exactly match the stock ones, that that would not affect engine 'mapping' (to use an EI term) because the spring is merely there to (and I'm sure I'm using the wrong terms) press a lever against a cam and as long as it's doing that, that's all that matters?

Thanks,

The strength of the spring is vitally important, which is why I used to grab several when I got the chance. Too weak will allow too much of an advance - catastrophic failure looms. Too strong isn't so bad but it's not running as well as it should.

[jharvey]

Grimly,Understood, thanks.

Meanwhile, I was home at lunch, confirmed that my Service Manual was for the GS as opposed to GSX (whether that matters or not - I'm guessing, no), and learned that my statement about 'being on the wrong side of the EI timeline by months’ in the earlier post was even more accurate than I thought. When I look at the ignition timing for the E model, the manual essentially says, ‘it depends’.

page a.jpg

Of the various models covered in the manual (E, L, S, etc.), some were only listing Transistorized as the type, where others, like the E, we’re listing both possibilities. So presumably, the final shift to EI took place during the 1980 model year.

[jharvey]

The Haynes manual (covering "GS/GSX 250 and 400 Twins - 1980 to 1981") also might offer some clues about the naming conventions – at least in 1980. On the model listing on first inside page, the “X” was being added to UK models, but American (and no doubt, by extension, the Canadian) names just used GS. I expect GSX was adopted all the way around in 81.

And while the Suzuki Service Manual doesn’t cover the spark advance (I’m guessing because these units were used in multiple models and displacements, and the Service Manuals were just to give information specific to each model), the Haynes Manual shows the part in question in all it’s glory.

page 2b.jpg

(No part# though.)

[bitzz]

The slide in your CV carb can "hang up" and do that. You might want to look at the carbs.
On every race bike I have ever owned I wired/locked the timing advance cam to full advance, and the revs don't 'hang up" like that.

.. and I too am Canadian, and to me a GS is 2 valve, and the GSx is a 4 valve.

[tom203]

This eBay item looks clean…..does it look similar to your setup?

https://www.ebay.com/itm/154868101545?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=g3OjUum3QUi&sssrc=2349624&ssuid=ARSR0K5ISZu&var=&widget_ver=artemis&media=COPY

[jharvey]

tom203, It looks close, but has a different part number (https://www.partzilla.com/catalog/su...gnal-generator) - 33120-47020 as opposed to 33120-44011 for the 400. Same thing with different part numbers? or something heavier duty for the larger displacement engine? (One of the things I'm missing about the Bike Bandit site, was that they always listed the part numbers of parts that 'superseded' the older ones.) I'll have to toss this at my mechanic and see if he can find out. But thanks, seriously, for pointing me at this. It looks to be in good shape and looks the same, and though the listing says, 'May not ship to Canada,' if they DO, for the sake of $25 bucks US it would probably be worth the gamble. Again, thanks.


bitzz, I'll ask the mechanic about the carbs when I take it in, thanks.

'and to me a GS is 2 valve, and the GSx is a 4 valve' - and yet, my 1980 GS is 4 valve (note rectangular cylinder head caps and the TSCC badge on the crankcase).

IMG_4946.jpg

My guess is that although Canada got the British/European version of the bike with 4 valves and 400cc, perhaps Suzuki Canada thought there might be confusion about GS north of the border and GSX south, so used the American naming convention that year. PURELY a guess on my part on the reason for the naming inconsistency, and I'm also guessing that GSX was adopted universally for 4 valves after that (though since I wasn't looking to buy a motorcycle after 1980, I wasn't paying attention).