Re magnetizing flywheel?

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mwoj
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Re magnetizing flywheel?

Post by mwoj »

So I have been thinking, once again about my weak spark. Someone had mentioned it could be due to the magnets losing their magnetism over time. So then I thought back to school and they had taught us how to transfer magnetism by means of hitting/rubbing two magnets together. Would that work for my flywheel? I have some pretty heafty magnets from hard drives that I can use. Am I completely mistaken? Can this work?>
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Jaguar
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Re: Re magnetizing flywheel?

Post by Jaguar »

won't know unless you try.
to see if you actually increased its strength go ahead and use this method to have a point of comparison:
place the KDX magnet on the table on its side, facing towards a magnetic compass. the magnet should be to the west or the east of the compass.
set the distance between them so that the needle deflects about 30 degrees.
mark where the magnet is, put the stronger magnet onto it so that they are attracted to each other (North to South pole), and then put the KDX magnet back where it was on the table and note the position of the compass pointer. If it is now deflecting more degrees then you have successfully increased its strength.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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Jaguar
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Re: Re magnetizing flywheel?

Post by Jaguar »

What I'd like to know is this: Does the KDX magnet have north/south alignment from end to end or from side to side?
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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kawagumby
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Re magnetizing flywheel?

Post by kawagumby »

There are many, many very old bikes that have not lost effective flywheel magnetism, so that angle is likely a lower probability than other causes.

Before messing with the magnets, I'd check the voltage generated from the stator coil first...if that is sufficient, the problem may be elsewhere.

Most motorcycles use composite magnets in the flywheels. If you strike them, they will shatter. Even if the magnets are iron, striking the magnets can cause you to lose what magnetism you have, and you will probably be unable to duplicate the process to properly reinstate the correct amount of magnetism. Believe it or not, if there is too much magnetism, it can overwhelm the ignition system. I learned this the hard way on a bike with an aftermarket flywheel that could only be used with an aftermarket stator. Calling the manufacturer, they explained that their flywheel had too strong of magnets for the stock stator windings which then overwhelmed the black box circuitry. The bike would start up fine, but ran like crap.
1994 KDX200, Beta 200rr, yz125, yz250, kx100 modded for adult, gasgas contact 250.
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Jaguar
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Re: Re magnetizing flywheel?

Post by Jaguar »

Due to the extreme heat that the flywheel magnets are exposed to, and possibly being dropped onto the floor, the old magnets lose strength.
It is a common problem with old Honda CRs. I had an '89 CR250 with that problem. Instead of spending $500 to replace the parts I just used my electronics ingenuity to precharge the CDI with voltage from a series of 9volt batteries to make up for the loss of voltage at low RPM from the stator coil (due to a weak magnet). It worked like a charm but that is not the point of this rant. It is that old bikes often have this problem.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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Re: Re magnetizing flywheel?

Post by jeswinehart »

Jaguar wrote:What I'd like to know is this: Does the KDX magnet have north/south alignment from end to end or from side to side?
Yes, 2 different polarity's between the 4 magnets. You can reinstall any which way you'd like and it will still make spark,,,, just at the wrong time. Here is some info that may be useful or interesting for you.
I have a KDX flywheel being mailed to me to encapsulate so the magnets stay in place.

john

http://www.kdxrider.net/forums/viewtopi ... 76&t=18659
mwoj
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Re: Re magnetizing flywheel?

Post by mwoj »

Is there a way to have the flywheel rebuilt?
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Jaguar
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Re: Re magnetizing flywheel?

Post by Jaguar »

I went to the 3wheelworld site that you posted but it required membership to view it.
any way that info can be made available to non-members?
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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Re: Re magnetizing flywheel?

Post by Friedom »

I just ordered a used Stator, and I think it's coming with a flywheel that I don't need. LMK if you're interested in replacing for a good low price.

Edit: not sure if it matters, this is off an E series.

Fun Wheel Drive
jeswinehart
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Re: Re magnetizing flywheel?

Post by jeswinehart »

3.jpg
3.jpg (574.44 KiB) Viewed 5953 times
Jaguar wrote:I went to the 3wheelworld site that you posted but it required membership to view it.
any way that info can be made available to non-members?
Sorry about not being able to view my link Jaguar.
Pictured is a oem tecate flywheel on left, kdx on right.

The kdx magnets are 180 degrees opposite positioned polarity wise.
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Re magnetizing flywheel?

Post by pumpguy »

During all of 1961 and into 1962 a talented engineer named Edgar T. Westbury wrote a series of articles on magnetos in the British magazine MODEL ENGINEER, which is still in publication.

These articles contained just about everything there was to know about magnetos up to that time, and included much information on how make your own for use on an IC engine to power a model boat or airplane. He writes about using low melting point metals like Zamak as filler material between the rotor or flywheel magnets.

Back in the day it was (probably still is) common practice to make a flywheel of this material with the magnets cast in.
I'm kind of surprised this technique is not used in our bikes today. IMO, it is superior to glued in place magnets.

I see no reason why ETW's techniques couldn't be used today, although some might object to the extra weight. Today modern pourable epoxy might be a better choice.

Back issues of MODEL ENGINEER magazine can be found from the publisher or TEE Publishing in the UK.
jeswinehart
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Re magnetizing flywheel?

Post by jeswinehart »

You mean like this Pumpguy ??? I have been encapsulating stock O.E.M. flywheels for about 5 years now to keep magnets from coming apart.

http://s1122.photobucket.com/user/jeswi ... html?o=192

I think you will get everything I put on u tube doing this way (sorry)

john
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Re magnetizing flywheel?

Post by jeswinehart »

wow, that fella you mentioned,,, Edgar T. Westbury ,,, what a interesting guy !
pumpguy
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Re magnetizing flywheel?

Post by pumpguy »

YEP, EXACTLY. Man, that's nice looking work! Glad to see someone's doing this. I always thought the stock method of magnet attachment was kind of Micky Mouse.

And, yes, ETW was a very interesting guy. I don't know his complete biography, but from what I understand, he could have made a ton of money in private industry, but chose to work on his own, experimenting and writing engineering articles for the Model Engineering hobby. I have all kinds of his articles and booklets that I've acquired over the years.
mwoj
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Re: Re magnetizing flywheel?

Post by mwoj »

Friedom wrote:I just ordered a used Stator, and I think it's coming with a flywheel that I don't need. LMK if you're interested in replacing for a good low price.

Edit: not sure if it matters, this is off an E series.

Fun Wheel Drive

email me michaelwojnoski@gmail.com
Friedom
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Re: Re magnetizing flywheel?

Post by Friedom »

mwoj wrote:
Friedom wrote:I just ordered a used Stator, and I think it's coming with a flywheel that I don't need. LMK if you're interested in replacing for a good low price.

Edit: not sure if it matters, this is off an E series.

Fun Wheel Drive

email me michaelwojnoski@gmail.com
Email sent

Fun Wheel Drive
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