Flywheel magnet source

[kjdad]

Maybe stated..as long as you have N,S,N,S then if should work right? Meaning, doesn't matter what N is in relation to the key or does it? I have a hard time thinking why it would matter as long as you are alternating the field..or am I way off?

[KDXGarage]

I think the magnet placement is quite critical as the gaps in the magnets means something. I THINK!

[Pressingonward]

I think it must matter, but I don't understand how you get one spark per revolution since everything seems to be symmetric - there's no obvious single trigger point for the CDI. I'll have to bug the electrical engineers at work and see if we can figure out the secret sauce.

[KDXGarage]

It sends a pulse at some point...probably important that be at the exactly correct time

[kjdad]

Yeah seems like magic to me. If you alternate the magnets all your doing when the engine spins is creating AC..no different then the lighting coil. I dont get how the position matters. Say you go S,N,S,N..what's the different..you still would get a field. The cdi gets the voltage..charges and when it hits full sparks? I'm not an engineer and totally interested how this works without points.

[kjdad]

And to add...could you even run the kdx motor in reverse? Seems like the ignition wouldnt know the difference. I get that there is both a ignition power and exciter (trigger) coils on the plate. I just dont see what the difference is between n,s,n,s or s,n,s,n would cause. As long as they alternate.

[kdxsully]

I think there’s a post on here when a guys engine was actually running in reverse. So if you retard the timing enough I guess that could happen. I don’t know how this stuff works, I just keep it the way it was when I knew it was working. I guess logically if the magnets are kept symmetrical noting would change, but why risk it?

[Blackflame444]

Does anyone have a picture or diagram showing magnet location/north south orientation on 1986 KDX stock flywheel? Another question. If I hold a compass near inside u shaped portion of magnet and get a North reading would that be a North magnet? And a South magnet with a South reading? Or is the polarity based on back/glued side of magnet? My flywheel has little raised stops inside that I'm guessing is for magnet placement. I just need to understand polarity reading using compass and polarity placement orientation to keyway.

Well, it just so happens I took pictures before I re-epoxied mine. A bit hard to tell in the photos, but the magnet that goes on the same side as the keyway has its south face facing in towards the center. The next one has its north face facing in towards center. The next one (opposite keyway) has its south face in towards the center. And the last one has its north face in towards center. In other words, you have two different magnet types - two with the concave face as their North pole, and two with the convex face as the North pole.

I tried to attach the photos, but it's not working and I don't have time to deal with it right now. I'll try to post them up sometime soon.

One note, this flywheel is off of a bike that had good spark, but I've never actually ran it - still a work in progress.

Thanks for that info 'Pressingonward'. I just saw Your post after I compared chrisperrera's '1986 cheap flywheel' post on switching to tecate flywheel to Mrs. Swineheart's images of a tecate flywheel magnet arrangement for Her magnet sales on ebay. Your info helped confirm. My magnets had all come undone but no damage occurred. I watched some vids on youtube for how to determine polarity of a magnet. Learned that if you point a compass at the inner concave side of the magnet the polarity of the magnet is opposite of the compass reading. So if it shows north on the side of the magnet that would point toward the crank it's actually south. Also if I hang that same magnet by a string that same inside portion of magnet will be pointing South as the backside gravitates North thus it's a South Pole magnet. That may be basic knowledge but I had no idea. I have a pic to post too but mine is not working either.

https://www.ebay.com/itm/4-Replacement- ... Sw2FVbPM38

That is not a valid link. Can you try again?

Picture attaching instructions are in my signature. Linking to a picture on the web is done from the Full editor section.

Figured it out...

1986 KDX.jpg (545.13 KiB) Viewed 4844 times

[Blackflame444]

Does anyone have a picture or diagram showing magnet location/north south orientation on 1986 KDX stock flywheel? Another question. If I hold a compass near inside u shaped portion of magnet and get a North reading would that be a North magnet? And a South magnet with a South reading? Or is the polarity based on back/glued side of magnet? My flywheel has little raised stops inside that I'm guessing is for magnet placement. I just need to understand polarity reading using compass and polarity placement orientation to keyway.

I’d buy a real magnet with a true N/S on it. I’d also wait until I had the new magnets in hand to discern which is which, in case they aren’t labeled. If they repel, it goes there. There’s a hand drawn diagram in the listing that shows magnet orientation for the tecate flywheel. It’s the same as a kdx but the the keyway and timing marks are in a different spot.

My magnets had all come undone but no damage occurred. I watched some vids on youtube for how to determine polarity of a magnet. Learned that if you point a compass at the inner concave side of the magnet the polarity of the magnet is opposite of the compass reading. So if it shows north on the side of the magnet that would point toward the crank it's actually south. Also if I hang that same magnet by a string that same inside portion of magnet will be pointing South as the backside gravitates North thus it's a South Pole magnet. That may be basic knowledge but I had no idea. I have a pic to post of proper placement for original 1986 KDX200 flywheel with magnet positions labeled but the attach image feature is not working.

[Blackflame444]

It's really none of my business, and of course you can do what you want but... I'm genuinely curious why on earth you would go to all this trouble rather than do the fairly simple stator mod with the newer flywheel... solving the flywheel magnet problem forever?

I am interested in doing that too. Are You talking about the Tecate flywheel mod? I couldn't find any of them flywheels either. Is there more flywheel stator mods besides that You know of that would work as long as they fit crankshaft and case correctly? From which year/makes/models of bikes/quads/trikes? Thankyou

[kdxsully]

I’m pretty sure we only know of the H model right now.

[kdxsully]

https://rover.ebay.com/rover/0/0/0?mpr ... 3450800118

[Blackflame444]

I noticed the face of my original flywheel has factory drill marks on the face of it which I'm guessing were made to ensure proper balance. If so could this be reason why people using a flywheel from different models aren't getting perfect results with timing and could this in turn damage the crank or other engine components over time? I've contacted several China aftermarket manufacturers giving them details about 86-88 flywheel issues. Hopefully they get an itch to produce it.

[kdxsully]

Some people have gotten perfect timing results using methods to set timing manually rather than just guessing. I doubt China would make one, and if they did, I’d rather not.

[Blackflame444]

Here is my pic of my original flywheel magnets before being re-epoxied with proper orientation... I ended up re-epoxying with JB Weld.

1986 KDX.jpg (545.13 KiB) Viewed 4854 times

[bob_jones]

I am interested in doing that too. Are You talking about the Tecate flywheel mod? I couldn't find any of them flywheels either. Is there more flywheel stator mods besides that You know of that would work as long as they fit crankshaft and case correctly? From which year/makes/models of bikes/quads/trikes? Thankyou

Install 1989-2003 (or whenever they stopped making them) model kdx200 or kdx250 flywheel directly onto shaft with no modifications whatsoever. You mod and reinstall stock stator. Nothing involving any other parts. No tecate anything. It's a very straightforward mod. There are multiple writeups about it on the boards. I think it's even been linked in this thread.

EDIT see below:

viewtopic.php?f=119&t=19867&p=179912#p179912

viewtopic.php?f=119&t=12423&hilit=Flywheel+mod

[Blackflame444]

Thankyou much!