Mechanical advance needed for Dyna S on '81 650E?

[t3rmin]

I've just spent an aggravating evening trying to get my ignition working in my 81 GS 650E and it appears I have a dead ignitor. Per the advice I've seen repeated many times in this forum, I'm looking at just replacing the whole darn thing with a Dyna S.

One thing that gives me pause is the requirement of adding a mechanical advance unit to non-points bikes when you install a Dyna S. However, after inspecting my stock signal generator, there is definitely a system of weights and springs in there that looks mighty like a mechanical timing advance.

Is my bike a sort of transition model with electronic ignition AND a mechanical advance, or am I seeing things? Does this mean a Dyna S would be a direct bolt-on for me?

Here's a picture:
View attachment 1008

 

[t3rmin]

Which one?

Which one?

After searching around some more, it does appear some bikes in the early 80's had both electronic ignition and a mech advance...

So here's another question: any idea which part number I need to fit this bike? DS3-1 is for the Kokusan ignition, which I have, but the year range doesn't match. DS3-2's year range includes 1981, but is for the ND ignition.

Has anyone out there fitted a Dyna S to an electronic ignition, stock mechanical advance bike with KD ignition? Which Dyna model # did you use?

Thanks!

 

[earlfor]

The bike is 25 years old. The odds are pretty good that at some time a previous owner replaced the ignition system. If you can read Kokusan on your current system, then it doesnt matter what the books say the bike was manufactured with, you will need the Kokusan Dyna.

The only difference between the kokusan and Nippondenso systems is the rotor.

Earl

After searching around some more, it does appear some bikes in the early 80's had both electronic ignition and a mech advance...

So here's another question: any idea which part number I need to fit this bike? DS3-1 is for the Kokusan ignition, which I have, but the year range doesn't match. DS3-2's year range includes 1981, but is for the ND ignition.

Has anyone out there fitted a Dyna S to an electronic ignition, stock mechanical advance bike with KD ignition? Which Dyna model # did you use?

Thanks!

 

[t3rmin]

Lets say it is a 1981 Kokusan electronic ignition with stock mech advance, would you say the DS3-1, which is listed for "1977-78 Suzuki, 550/750 four cylinder (KD)" would fit up, rotor-wise? I guess the real question being, has the Kokusan ignition changed since 1978? (i.e. is the Kokusan ignition is unchanged between 1977 and 1981?)

I was leaning toward the DS3-1 (KD), but I saw elsewhere in the forums somebody said they've never seen an electronic ignition, mech advance bike take anything other than the DS3-2 (ND). So I thought perhaps there was a reason for that year range, and that the ignition changed after 1978 such that maybe the DS3-2 would be the right fit regardless...

Anyway, thanks for humoring all my questions!

 

[earlfor]

Since a 1981 is not listed for a KD ignition by Dyna, its a safe bet your ignition came from an earlier model. It may not have come from a 550/750 though.
The only difference I know of between the KD and ND is that the shaft is longer on one of them. I cant remember which one it is though. It is a sure thing that if you have a KD ignition, no year ND designation will work because the sensor windows (rotor to pickup) will not line up if the shaft length is incorrect. You have to use a KD system if that is what you now have.
The determining factor is the shaft length on the mechanical advance unit.
As far as I know, that does not vary between any models. That is an educated guess though. I do not have firsthand, tabulated data.
The probabilities are you have an earlier model KD ignition system. I would
order the DS3-1 (KD) Dyna S. I am reasonably sure it will fit. I would call the retailer, explain the situation and ask if there would be any problem with returning it if on receipt, you find the dimensions will not fit your bike.
(a lot of places have a no return policy on electrical items) As I say, I would order it. I expect it will fit fine, but unfortunately. I cant give you a been there, done that guarantee. There is some risk.

Earl

Lets say it is a 1981 Kokusan electronic ignition with stock mech advance, would you say the DS3-1, which is listed for "1977-78 Suzuki, 550/750 four cylinder (KD)" would fit up, rotor-wise? I guess the real question being, has the Kokusan ignition changed since 1978? (i.e. is the Kokusan ignition is unchanged between 1977 and 1981?)

I was leaning toward the DS3-1 (KD), but I saw elsewhere in the forums somebody said they've never seen an electronic ignition, mech advance bike take anything other than the DS3-2 (ND). So I thought perhaps there was a reason for that year range, and that the ignition changed after 1978 such that maybe the DS3-2 would be the right fit regardless...

Anyway, thanks for humoring all my questions!

 

[t3rmin]

earlfor:

Hey, that's good enough for me. Thanks much!

*EDIT* Ordered the DS3-1 from z1enterprises.com. Will let you know how it goes. Note for any 650E owners out there, z1enterprises is one of the only sites that even lists parts for the 650E model.

 

[t3rmin]

Just got this reply from Dyna, so I'm really crossing my fingers. I haven't gotten out to measure my bike yet, but they haven't instilled much confidence! The part is ordered and on its way, so we'll just have to see...

Please note the outside diameter of the ignition plate assembly for the
Suzuki Dyna "S" is 3.665" and has 3 bolt holes. We believe that the plate
assembly in your bike to be somewhat smaller than this and that design is
something we do not make. Of course, the Kokusan Dyna "S" is part # DS3-1, but for the older and larger plate assembly.

 

[t3rmin]

GOT IT! But still need some guidance...

GOT IT! But still need some guidance...

Well the Dyna S arrived yesterday, and it fit almost perfectly, so that's a relief! Thanks again for the advice, earlfor!

One more question, though. I've got the thing installed and wired up properly (it starts and runs!), but I'm getting erratic spark on the 2-3 cyls (timing light only shows a spark every once in a while; I know a timing light may miss a signal here and there, but it's more off than on and the 2-3 pipes seem to stay cold) and I'm wondering if it has something to do with the way their rotor fits on my advance unit shaft.

The Dyna rotor is just a little shorter than the stock one, so it has about 1.5mm of play on the shaft. It's not enough for the rotor "key" slots to slip out of the advance weight nubs (I think), but I wonder how sensitive the alignment of the little magnet is?

Can anyone give me a sense of how the rotor should align with respect to the pickup coils? Should it be recessed a bit, sticking out a bit (like the stock rotor), or flush? If the magnet placement is indeed very sensitive, it would make a difference whether I shim the rotor on the outside (thus pushing it in towards the crank) or on the inside (thus pushing it out away from the crank), right?

I realize the problem at this point may be completely unrelated to the rotor, since I'm using the stock wiring harness of questionable integrity, plug wires/caps of questionable quality, and plugs that probably should be replaced, and I will address those issues ASAIHT (As Soon As I Have Time), but I'm still concerned about the play in the rotor.

 

[t3rmin]

Once again I've answered my own question. ;-)

After further testing during my lunch hour, I need to shim on the outside and push (and keep) the rotor back towards the crank. Otherwise it wiggles out and I start to lose sparkage. It only takes a tiny amount of movement, so it would appear that magnet needs to be aligned fairly precisely.

I've got a rubber washer on there now, but I'm worried that might bind against the plastic rotor and prevent the mechanical advance from actuating. I need to find something that's flexible enough to fit over the tangs at the end of the shaft but slippery enough to not interfere.

And of course now that this problem is solved, I've noticed gas in my oil so I have to rip the carbs out and clean 'em. Oh well.