Difference b/w 8 pole and 11 pole flywheel By jstluise (Read 16,025 times)

[jstluise]

I'm in the process of an 11 pole upgrade on my Kymco Agility 125. I got all the components from John (tvnacman), and I just finished disassembling yesterday so I could compare the stock flyhweel (for 8 pole stator) to the new flywheel (11 pole stator). A couple things I noticed:

1) The relationship between the key way on the hub and the timing marks are not the same (not a big deal I guess). The bigger issue, is that the relationship between the key way and the ignition pickup (trigger pulse) is not the same...I don't see how this could not cause a problem with ignition timing... Here is a picture (the Kymco is on right, I think). You can see the key way on each and the ignition pickup on the outer diameter.



2) To my surprise, the old flywheel and the new flywheel contain the same number of magnets (8). Also, the Kymco is heavier and the magnets are stronger. I was able to test the number of magnets by simply moving a piece of metal (a socket) around the inside of the flywheel. I made a quick video:

I show the Kymco first and the new flywheel last. You can see the socket stop on each magnet.

In conclusion, I see no difference between the new flywheel and the old flywheel as far as the magnets go (if anything, I suspect the original flywheel would be better because of the stronger magnets). The big difference is the ignition pickup; I feel like the new flywheel will give me timing issues. Since the magnets are the same for each flywheel, I don't see the problem with using the original flywheel.....but everywhere I have read online says that the 8 pole and 11 pole flywheel are different and they aren't interchangeable.

John is aware of this issue, but I wanted to get this out there see what everyone else thinks. For anyone that has done the upgrade, did you notice any differences between the flywheels?

PS I will be taking some measurements when I get home to see if there are any noticeable differences between the flywheels' geometry.

[Alleyoop]

The difference really is on the STATOR itself that is why the Pickup magnet is in a different position on the FLYWHEEL. To see the difference place the new stator on the old and new and you will see where the Stators WHITE COIL THAT TRIGGERS THE PICKUP hits on the inside of the Flywheel.
Alleyoop

[tvnacman]

Lets see what happens with the measurements.

John

[jstluise]

Aug 2, 2012 12:02:32 GMT -6 Alleyoop said:

The difference really is on the STATOR itself that is why the Pickup magnet is in a different position on the FLYWHEEL. To see the difference place the new stator on the old and new and you will see where the Stators WHITE COIL THAT TRIGGERS THE PICKUP hits on the inside of the Flywheel.
Alleyoop

I did notice the difference with the stator. I guess I don't fully understand how the pickup magnet/pickup coil work. My initial understanding was that when the magnet passed by the coil, a pulse was sent to the CDI which told the CDI to fire the spark plug. If this was the case, then the position of the pickup magnet on the flywheel is critical.

After reading around online, it seems that the CDI just uses the pickup magnet/coil as a reference to know where the piston is relative to TDC, but not necessarily as the trigger for the spark plug. Still, it seems like the position of the magnet matters, since the CDI is programmed for a certain position. I am still missing something here...maybe the CDI works using both the pickup coil and the white coil on the stator?

Obviously the stator/flywheel I got from John works, since many people have used it. I'm just curious why it works.

[Bashan]

I thought there would be 11 magnets with an 11 pole stator to energize each winding smoothly. It seems like 8/11 would be fighting the AC current but maybe it works out mathematically. One pole, sometimes two on larger stators, is dedicated for charging the CDI. This coil, called the magneto, is the wrapped one. The CDI sucks up juice from the magneto waiting to discharge it when the trigger tells it to. So there's no timing issue with where the magneto is placed. The CDI fires each revolution although it really only needs to once every two revs on a four stroke. Therefore, the trigger could be 180 degrees from one flywheel to the next and it wouldn't matter. What DOES matter is the orientation of the trigger for firing. I would think it has to be exactly the same for the proper firing time. I can't tell from your pic if the Woodruff and trigger magnet are on the same degree on the flywheel. Also, Kymcos are a different animal, I hope the electrics are compatible with this upgrade. Rich

[Deleted]

The flywheels for the 8 and 11 coil Stators are the same in size. both the 8 coil and 11 coil stator fit in the flywheel of an 8 or 11. Now we have seen a few Flywheels for the 11 coil that actually came with 11 magnets inside but i have not seen those for a long time. Right now my other scooter has a 11 coil stator with the 8 coil Flywheel and works just fine.

[jstluise]

Aug 2, 2012 14:21:20 GMT -6 Bashan said:

The CDI fires each revolution although it really only needs to once every two revs on a four stroke. Therefore, the trigger could be 180 degrees from one flywheel to the next and it wouldn't matter. What DOES matter is the orientation of the trigger for firing. I would think it has to be exactly the same for the proper firing time. I can't tell from your pic if the Woodruff and trigger magnet are on the same degree on the flywheel. Also, Kymcos are a different animal, I hope the electrics are compatible with this upgrade. Rich

[/b][/quote]

If what you are saying is true (ie the CDI fires exactly when the pickup magnet passes over the pickup coil), then the relative position between the pickup magnet on the flywheel, the pickup coil, and the crankshaft must not change. In my case, with the new flywheel and since the location of the pickup coil doesn't change, this relationship is thrown off.

Not sure if I agree with you saying it can be 180 deg off, since it would be firing at BDC instead of TDC. Maybe I misunderstood.

I'm beginning to wonder about whether or not the CDI will work with this upgrade. See below...

The flywheels for the 8 and 11 coil Stators are the same in size. both the 8 coil and 11 coil stator fit in the flywheel of an 8 or 11. Now we have seen a few Flywheels for the 11 coil that actually came with 11 magnets inside but i have not seen those for a long time. Right now my other scooter has a 11 coil stator with the 8 coil Flywheel and works just fine.

I forgot to bring a set of calipers home to measure (will measure first thing tomorrow), but from using a scale, the ID looks to be the same between the two flywheels. Did you notice a difference between the location of the pickup magnet on each flywheel?


Now, the next problem I discovered. With the original setup, there was only one wire running to the CDI which was for the pickup coil. The new stator now requires two wires running to the CDI, the pickup coil (okay, good) and another wire (red/black). I imagine the red/black wire is for the magneto, but not sure where to connect it on the CDI (is there an empty pin or does it splice into a currently used pin?). Wondering if the CDI needs to be upgraded as well, though I never read about anyone else doing that. Thoughts? Anyone making the upgrade from 8 pole to 11 pole have to switch out their CDI?

My current CDI has the following 4 wires running to it: switched power, pulser (pickup coil), ground, ignition coil. According to the diagrams I've seen (this one in particular i53.tinypic.com/2jacdvm.jpg), the additional wire is the red/black wire from the stator. I haven't looked yet, but I may have an open pin the the 2-pin connector for the CDI...my wiring diagram for the Kymco sure makes it look that way. I'll have to take a look.

Thanks a lot everyone!

EDIT: I just went out to take a look at the CDI. Stock, there are two unused pins on the CDI (one on the 4-pin connector, and one on the 2-pin connector). I guess the red/black wire from the new stator should go to the unused pin on the 2-pin connector? Is this correct? (I am just going off the diagram I referenced earlier)

[justbuggin]

i would use your orginal flywheel with the new stator the new flywheel looks to have the pick up magnet 180 degrees out which is just a mistake when manufactured

[jstluise]

Aug 2, 2012 23:29:52 GMT -6 justbuggin said:

i would use your orginal flywheel with the new stator the new flywheel looks to have the pick up magnet 180 degrees out which is just a mistake when manufactured

That is my thought as well. Its weird...not quite 180 deg off...more like 160 deg or so. Hard to tell without measuring it somehow.

[Alleyoop]

EDIT: I just went out to take a look at the CDI. Stock, there are two unused pins on the CDI (one on the 4-pin connector, and one on the 2-pin connector). I guess the red/black wire from the new stator should go to the unused pin on the 2-pin connector? Is this correct? (I am just going off the diagram I referenced earlier)

I think you have a DC CDI on that scoot. How your describing that it only has one wire on the two plug side is usually how a DC CDI is wired. To Verify if it is a DC CDI Test the wire if it registers 12v it is FED directly by the BATTERY.
Alleyoop

[jstluise]

Aug 3, 2012 1:46:13 GMT -6 Alleyoop said:

I think you have a DC CDI on that scoot. How your describing that it only has one wire on the two plug side is usually how a DC CDI is wired. To Verify if it is a DC CDI Test the wire if it registers 12v it is FED directly by the BATTERY.
Alleyoop

I guess I should have been more clear. All of the pins on the CDI exist (4+2), however, the wiring harness of the scoot only uses 3 on the 4-pin and 1 on the 2-pin. I'm not sure if your diagram is referring to the wires coming into the CDI or referring the the CDI itself. Anyways, here are some pics:





The CDI is a Kymco TYC-D401. I couldn't really find any info on it.

Now what do you think? DC or AC CDI?

I can tell you that the single wire on the 2-pin connector is coming directly from the battery (via ignition switch). Just like it is in the diagram: i53.tinypic.com/2jacdvm.jpg%29

Thanks!

[Alleyoop]

Ok, then IT IS A DC CDI, if the LONE WIRE ON THE 2 PLUG connector is coming from the Battery.
That means if your battery is bad your scoot will not run, you always need a good battery. If you take your battery out it will not run. Unlike an AC CDI which is FED by the STATOR and in that mode you can take the Battery out and your scoot will run.
Alleyoop

That diagram is an AC CDI not a DC CDI, notice the red wire is coming from the STATOR NOT THE BATTERY.

Very easy to test get a volt meter and test that SINGLE WIRE on the CDI 2 plug, If it registers 12v its a DC CDI.

[Bashan]

Alley's right, it's a DC CDI which doesn't surprise me on a Kymco. DO NOT plug the red/black AC power feed from the new stator into your DC CDI. You'll need to get a AC CDI for your new system. Sprocket says pony up the extra bucks and get a NCY, they have uber capacitors. The four plug, whether AC or DC, has to have a trigger input and coil output which yours does. The remaining two ports are grounds, you should be able to hook yours up the same on the new CDI and it shouldn't matter.

You're right, the flywheel can't be 180 off, that would be BDC. Sorry, brain fart. Your CDI changes the advance on the spark as the RPMs change. It has to or the engine wouldn't run at certain RPMs. The trigger magnet tells the CDI where the flywheel is set in relation to the crank and how fast the flywheel is moving. If the magnet is set at a different number of degrees for the initiation of the spark it will throw the whole system off. The degree for starting that cycle must be the same on both flywheels. Rich

[tvnacman]

Changing the stator makes going to ac cdi very easy.

John

[jstluise]

Aug 3, 2012 2:22:58 GMT -6 Alleyoop said:

Ok, then IT IS A DC CDI, if the LONE WIRE ON THE 2 PLUG connector is coming from the Battery.
That means if your battery is bad your scoot will not run, you always need a good battery. If you take your battery out it will not run. Unlike an AC CDI which is FED by the STATOR and in that mode you can take the Battery out and your scoot will run.
Alleyoop

That diagram is an AC CDI not a DC CDI, notice the red wire is coming from the STATOR NOT THE BATTERY.

Very easy to test get a volt meter and test that SINGLE WIRE on the CDI 2 plug, If it registers 12v its a DC CDI.

The scoot will (kick) start and run without a battery (I've done it). Remember, you still get DC power via the R/R (which is connected to the batt). But, it will not run without a battery AND a R/R (ie no DC power). But, I get your point.

So why do we still have DC power running into the AC CDI (one wire is DC from switched power, the other is from the stator)? I misread the diagram. The wire I saw is labeled as the kill switch wire...which doesn't mean there is DC power coming in on it, right? Not sure how the kill switch is wired up...I've actually read about not having a kill switch wire at all...? I just read the kill switch tutorial in the library and all the kill switch wire does is go to ground to stop the motor. Either by the run/stop switch on the scoot or the ignition switch. So, minor rewiring on the ignition switch when going from a DC CDI to an AC CDI.

If my CDI is a DC CDI, then why is there an additional pin on the 2-pin input? It it just a dummy pin or does it actually do anything?

After looking at pictures of other 8 pole stators, they do have an additional wire (as opposed to mine that has 2 + the pickup wire)...so I guess you guys are right. Is there anyway to test the difference between a DC CDI and an AC CDI?

I've researched AC/DC CDI and I'll have to agree that I have a DC CDI. It is larger and DC power goes to one pin on the 2-pin connector. Seems like that is the only way to determine if it is AC or DC.

Question: Can't I just keep my DC CDI and not use the red/black wire off the stator? I mean, I would still have DC power powering the CDI just like before, so it should work. I guess the downside is that you aren't utilizing the standalone coil in the stator for the CDI...right? I just read that DC CDIs are better (scooterdoc.proboards.com/index.cgi?board=electrical&action=display&thread=4996), so if I won't notice a difference then I can avoid having to buy a new CDI.

I measured the dimensions of the flywheels. Both IDs are nearly identical (90mm)...they are within .2mm of each other. Seems like using the original shouldn't be a problem in that sense.