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Main Area => General GS500 Discussion => Topic started by: zak1n on August 01, 2020, 06:50:07 AM

Title: flywheel rotor modification / repairing
Post by: zak1n on August 01, 2020, 06:50:07 AM
Hi guys,
is there anyone who modified or repaired flywheel rotor? I already have a third rotor in 3 years and the last one starts way to hell - I have some parts in oil pan from that sh*tty glue

I have only 3 options :
1) pray to godzille
2) use rotor from different model
3) repair it ( like here - shorturl.at/jHKQX )

https://ibb.co/Sw9YZJr
Title: Re: flywheel rotor modification / repairing
Post by: SK Racing on August 01, 2020, 07:36:04 AM
If by "repair" you mean "glue the magnets back", then I suggest you use Loctite 480, a rubberized cyanoacrylate (like Superglue) which is specially made for securing magnets.

Tip: Clean the surfaces well before gluing.

Edit: If more than two magnets are loose, make sure you glue them in in the correct positions. The magnet polarities should alternate around the circumference of the rotor, i.e. north, south, north, south, etc.

(https://i.imgur.com/Y05LgO9.jpg)
Title: Re: flywheel rotor modification / repairing
Post by: The Buddha on August 01, 2020, 04:38:56 PM
3rd rotor ? You've got some other cit in there that's crooked - stator, starter clutch etc etc.
Did it make a metallic knock sound while starting ?
Does the stator look damaged ?
Is your crank straight on that side ?
You installing it straight or cross threading it ?
Was it dropped on the left side ?

Cool.
Buddha.
Title: Re: flywheel rotor modification / repairing
Post by: Joolstacho on August 01, 2020, 04:46:17 PM
That's for sure... 3 rotors in 3 years? look for the problem that's causing that!
Title: Re: flywheel rotor modification / repairing
Post by: zak1n on August 02, 2020, 01:38:22 AM
Hi guys,
thanks for answers

SK Racing> are you sure with 1k glue? I mean if it have heat resistance

Yes 3 rotors in 3 years. I drive around 10 000km per year + we have very bad roads. I guess high temperatures, bad roads and low quality

Motorcycle was never dropped, without any problems or knocking - only big vibration around 5k but I guess it's normal (yes I have rubber under tank).
Two time all engine rebuilt( with new starter clutch) with all measuring with original parts from suzuki.

first time- damaged rotor + stator - knocking + charging failure
for the second time- It was luck. I changed alternator cover gasket and noticed that one magnet was free - stator ok
for the third time - I changed the oil and noticed parts from glue

I spoke with a next suzuki motorcycle owners and it is common failure in all modes. For example here SV1000 dropped 5 from 6 magnets - https://www.youtube.com/watch?v=BHyAx80gy9o






Title: Re: flywheel rotor modification / repairing
Post by: SK Racing on August 02, 2020, 02:56:44 AM
SK Racing> are you sure with 1k glue? I mean if it have heat resistance

Loctite 480 heat resistance is better than that of epoxy. Sure, you get slightly higher temp rated epoxies, but epoxy is usually quite brittle - unlike the rubberized stuff made for bonding magnets.

In any case, the crankcase/alternator/rotor doesn't get that hot. Nowhere near the temperatures you see at the cylinder head or exhaust ports, for instance.
Title: Re: flywheel rotor modification / repairing
Post by: The Buddha on August 02, 2020, 07:28:23 AM
Yea that SV1K issue is known, we swap em with a smooth magnet, I dont recall from what bike ? SV650 maybe ? No idea.

The 6 piece magnet is such a disaster - look into neodymlum magnets and machine up and drill and tap a drum etc - lot of machine work. Who knows maybe the quality of the magnet is now junk. I know chinese crap sold for bikes like the XS650 - by mikesxs or other people is total crap.

If the center hole isn't exactly perfect or you cant crank it to the right torque etc, it can wiggle round the crank and cause all sorts of problems.

Cool.
Buddha.
Title: Re: flywheel rotor modification / repairing
Post by: The Buddha on August 02, 2020, 09:04:14 AM
Did a GS450 have a smooth round rotor ?
I know GR650 did and its almost the same as the GS one, but its has a 2 stage disengaging flywheel - not sure where its located or has any connection to the rotor.
Cool.
Buddha.
Title: Re: flywheel rotor modification / repairing
Post by: zak1n on August 02, 2020, 09:07:19 AM
I read a lots of forums about damaged rotor all weekend and I found one thing - all brands have same problem (only uncovered magnets) with kokusan rotors

Maybe but only maybe can be used - looks the same like gs500īs rotor - kawasaki KLE 500 https://www.cmsnl.com/products/flywheel_210501148/#.XybbTigzaUk  - maybe a few minutes on the lathe or welding.

and again some problem like me :D
https://www.horizonsunlimited.com/hubb/kawasaki-tech/kle-500-no-oil-pressure-87692

but why am I writing - what do you think about this "fix"(KLE 500) with 2k glue + balancing? He wrote it works


(https://img.motofotky.cz/upload/images/forum/2019/46/504261_7b52bdcb7b38a6292a8a07a405d80521.jpg)
(https://img.motofotky.cz/upload/images/forum/2019/46/504263_64f29d11ab3aa411de231fbf896052e0.jpg)





Title: Re: flywheel rotor modification / repairing
Post by: SK Racing on August 02, 2020, 09:21:46 AM
Filling-in the gaps between magnets is an excellent idea. Mix some (a lot) of microballoons (tiny glass bubbles) into the epoxy to get a really thick paste, then it won't run out so fast. Cleaning up with a rag and acetone before the epoxy sets completely makes for a neat job.
Title: Re: flywheel rotor modification / repairing
Post by: Bluesmudge on August 02, 2020, 09:38:18 AM
Did a GS450 have a smooth round rotor ?
I know GR650 did and its almost the same as the GS one, but its has a 2 stage disengaging flywheel - not sure where its located or has any connection to the rotor.
Cool.
Buddha.

I think GS450 was a 3 magnet design. Still better than the 6 magnets.
Title: Re: flywheel rotor modification / repairing
Post by: The Buddha on August 02, 2020, 11:22:11 AM
Did a GS450 have a smooth round rotor ?
I know GR650 did and its almost the same as the GS one, but its has a 2 stage disengaging flywheel - not sure where its located or has any connection to the rotor.
Cool.
Buddha.

I think GS450 was a 3 magnet design. Still better than the 6 magnets.

Cant have an odd number - I mean you could but it would be stupid. How do you arrange N and S so you get alternating ...
6 pole = N S N S N S for a 360 rotation.
4 pole is N S N S and your 360 is done.
3 pole would be N S S or N N S for 360.
No that's not going to work.

Is it 3 piece magnet but magnetized end to end - making (N S) (N S) (N S) ???? so its 6 pole but 3 magnet - The problem with that would be the magnetic lines of force with short circuit across to the next pole, you may actually have these magnets sliding off sideways unless bolts in the drum, in which case they would produce poor poor electricity.

Cool.
Srinath.
Title: Re: flywheel rotor modification / repairing
Post by: Bluesmudge on August 03, 2020, 09:48:06 AM

Cant have an odd number - I mean you could but it would be stupid. How do you arrange N and S so you get alternating ...


I don't know how it works Mr. Tesla, I just know what it looks like:

(https://i.ebayimg.com/images/g/WXgAAOSwjPpbmuR4/s-l1600.jpg)
Title: Re: flywheel rotor modification / repairing
Post by: SK Racing on August 03, 2020, 12:22:29 PM
I think Srinath is right that the three magnets are magnetized end to end, giving six poles. It's not such a far-fetched idea. CD-ROM/DVD drive motors found in PC's use one piece ring magnets with 12 poles.

A three-phase alternator requires even numbered poles. Three poles won't work. Do a simple test if you have such a rotor as in the picture above. Take a loose magnet and move it over the rotor magnets. It should be attracted and repelled by like and unlike poles.
Title: Re: flywheel rotor modification / repairing
Post by: The Buddha on August 04, 2020, 12:47:19 PM
This end to end is a terribly inefficient idea. The 6 pole type is N S N S N S with each of those poled facing the stator. Talk about cutting through magnetic lines of force LOL
That's why a 6" wide Heil style ribbon tweeter will easily out perform a 6' long carver style ribbon and keep ruler flat impedance etc etc. Anyway get like a bunch of these -
https://www.kjmagnetics.com/proddetail.asp?prod=BX082CS-P&cat=19

Bolt em in NSNSNSNSNSNS like 24 of em onto a drilled and tapped rotor shell.
So instead of cutting through 6 poles worth of N5-N7 ceramic magnets per 360 degrees of crank rotation you'd cut through 24 of N42. Can you say instant sparking from everywhere.

No, just put like 6 of those farther from the stator. You can always add
You can always get it closer by putting a spacer under the magnet.
BTW in an alternator it makes no difference, but in audio you cant have too many weak and strong spots, it makes it sound like chit. But a alternator wont even matter, not even cause a significant ripple cos its 3 phase and rectified/regulated etc.

Cool.
Buddha.
Title: Re: flywheel rotor modification / repairing
Post by: SK Racing on August 04, 2020, 01:45:45 PM
Anyway get like a bunch of these -
https://www.kjmagnetics.com/proddetail.asp?prod=BX082CS-P&cat=19

Bolt em in NSNSNSNSNSNS like 24 of em onto a drilled and tapped rotor shell.
So instead of cutting through 6 poles worth of N5-N7 ceramic magnets per 360 degrees of crank rotation you'd cut through 24 of N42. Can you say instant sparking from everywhere.

No, just put like 6 of those farther from the stator. You can always add
You can always get it closer by putting a spacer under the magnet.
BTW in an alternator it makes no difference, but in audio you cant have too many weak and strong spots, it makes it sound like chit. But a alternator wont even matter, not even cause a significant ripple cos its 3 phase and rectified/regulated etc.

Having more than 6 alternating pole magnets will change the voltage of the alternator. With 24 magnets for instance, one will have to reduce the number of windings to get the stock voltage. 24 magnets instead of 6 will require 24/6 = 4 times less winding turns per stator tooth. I'm not saying it's a bad idea, but be aware of the pitfalls when you redesign the geometry of the alternator.

Far easier to either use a new or used rotor in good condition or stick the magnets back in on a damaged one.

There is another source of magnets in the USA. One that I've used in the past for PM alternators that I've designed and built.
https://supermagnetman.com (https://supermagnetman.com)
If you don't mind the extra cost, they will have special sizes manufactured to your specs.
Title: Re: flywheel rotor modification / repairing
Post by: The Buddha on August 04, 2020, 02:05:43 PM
PS: Correct but effective voltage is controlled by the R/R - If too low, it cant get it up, but if high, unless its sparkingly high, it will be fine.

But it will hit peak voltage in 1/2 the rpm. Usually the bike voltage peaks ~4-4500, past that current and voltage stay steady for a bit but 8K+ it starts to drop cos the spark uses more than it does @ say 4K and the alternator doesn't produce any more.

In any case IMHO -

Totally doable. Someone should do this. Get 12 of them in case you needed more than 6.
They should be thinner than the current ones so you can space them inward if you need.
They should be narrow enough that when you put a washer under it, it doesn't still hit the edges before the bolt gets tight. As in, you dont want it to be a true chord of the circle. You want it to have the chord not contact the circle.
Bolt in 12 kinda far away from the stator and try and start it and measure the voltage.
If too high, either try 6 poles or moving them further away from the stator.
You're essentially making the same 6 pole magnet as a 12 pole with bolted in poles with adjustable spacing to make the correct voltage and not destroy itself @ rpm.
Cool.
Buddha.
Title: Re: flywheel rotor modification / repairing
Post by: SK Racing on August 06, 2020, 02:26:43 PM
All this talk about magnets got me thinking... and wondering about the magnets in the GS500 rotor.

There are six magnets. Are they polarized as one pole over the entire length of the magnet? ...or different poles at the two ends of the same magnet?

Can someone check, please? Just hover any loose magnet over one of the magnets stuck inside the rotor and see if it attracts (or repels) along the entire length of the magnet.

I don't feel like disassembling the engine of my bike just to do this test, but I would really like to know.
Title: Re: flywheel rotor modification / repairing
Post by: The Buddha on August 07, 2020, 03:47:53 AM
They are set NSNSNS facing the stator in a circle.
The magnetic lines of force are going to sort of look like a horseshoe or a ( shape N->S.
The windings of the stator are radial so they are like - sticking into the middle of the ( 
That results in the best path across the magnetic lines of force for the coils.
That's just from common sense and 10th grade electricity classes in Physics.
Yea I remember what I learnt in 10th grade - just not what I learnt in college. I wish I could blame the beer, except I didn't drink back then ... lets just say Petrol fumes OK yea that's what killed off all the brain cells.

Cool.
Buddha.
Title: Re: flywheel rotor modification / repairing
Post by: SK Racing on August 07, 2020, 04:06:03 AM
Thanks, but have you tested the magnets in a GS500 rotor? 

My question was if the whole magnet is magnetized (through the thickness) as one single pole, i.e. either North or South. I suspect that each magnet is dual-pole: N one end and S the other end with a neutral zone in the center.

I know how alternators work. I design and build 3-phase electric motors, alternators and wind generators as a hobby and sometimes for clients, so I'm on top of the technology. I'm just not sure what exactly is in the GS500 and I don't feel like stripping my bike to find out. Someone with a loose GS500 rotor can easily do the test for me if he/she has a spare magnet. (as explained in my previous post)  8)

Title: Re: flywheel rotor modification / repairing
Post by: The Buddha on August 09, 2020, 06:38:22 AM
I'm pretty sure the magnets are not neutral zone in the middle and one end is N and other is S. The lines will short to each other, but the 3 magnet ones have to be which means there is enough magnetic lines around the poles as a sort of spill over.
In speakers we dont like that stray magnetism cos it distorts and does terrible stuff.
I have to check - I got atleast 1 motor with that accessible, unfortunately its 100 miles away in my other house where I was yesterday - but next run is ~1 month away.
Cool.
Buddha.
Title: Re: flywheel rotor modification / repairing
Post by: SK Racing on August 09, 2020, 07:53:36 AM
Only when you can and remember to do it, Srinath.

The idea of multiple poles in one elongated magnet is not so far-fetched. The Gauss lines are concentrated around the poles and don't affect the other poles (much). The majority of brushless motors in computers use ring magnets with typically 12 poles; - hard drive motors and also DVD and CD drives use it.

The reason I'm suspecting there are 12 poles in die GS500 is that the stator winding scheme (ABCABC...etc.) doesn't work for a rotor with 6 poles, but it does for 12 poles.

From what I've seen online, the GS500 uses the ABCABCABCABCABCABC winding scheme or pattern. That works for 18 tooth 12 pole machines. The winding scheme for 18T 6P would be AbCaBcAbCaBcAbCaBc. Capitals are for clockwise turns and lower case for anti-clockwise turns.

This is an example of a magnet with multiple poles. Source: https://www.indiamart.com/proddetail/ring-magnet-14563188130.html (https://www.indiamart.com/proddetail/ring-magnet-14563188130.html)

(https://i.imgur.com/GkUyz9P.jpg)
Title: Re: flywheel rotor modification / repairing
Post by: sledge on August 09, 2020, 09:57:55 AM
The alternator has 18 teeth
Divide by 3 (the number of phases it produces)
Gives you 6 teeth per phase.
Impossible to have more poles than teeth therefore.........it can only be a 6pole. 

Twist 2 of the three output leads together and put DC across them and the single remaining lead.
Hold a compass to the end of every tooth in sequence and expect to see the following pattern.

nnS nnS nnS nnS nnS nnS  or
ssN ssN ssN ssN ssN ssN

The alternator produces up to around 90VAC.....no idea of the frequency. Based on the synchronous speed of 6 pole AC machine it may be 50Hz at around 1000rpm........but I am not sure about this. It would depend on the number of poles in the rotating field. It will be connected in star (wye) rather than delta The maths say there will be less voltage needed across each leg which means less copper is needed to produce the same output voltage and the insulation system can downgraded, meaning savings in cost and size.

This is the accepted way used by service and repair personnel to determine the number of poles in an AC winding, (and in the case of standard squirrel  cage induction motors the speed), when the info is unknown or unsure. If the machine has been rewound or the inter-coil connections broken it will also indicate any if any of the coils are reversed.

Holding a compass to the flywheel magnets will also determine the amount of poles it contains, where they are located and how they interact with each other.

I never reached the heights of machine designer but I have spent coming up to 35 years at the oily end involved with the hands on repair, maintenance and in some cases the rewinding of all forms and aspects of rotating electrical machinery....... up to 33kv and about 25 tons  .........Ask our mutual buddy Ken  :)


Happy to offer my advice.
Title: Re: flywheel rotor modification / repairing
Post by: SK Racing on August 09, 2020, 12:13:56 PM
Thanks for your input, Sledge. All induction motors are asynchronous, i.e. it requires slip in order to induce current in the rotor winding. In contrast, PM (permanent magnet) motors and alternators, like the one found in the GS500 are synchronous. They operate according to different design criteria and rules.

I like your idea of using a compass to detect the poles in the rotor. Hopefully, it will tell me the number of poles without disassembling.  :thumb:


The winding scheme for the GS500 alternator should look like this: (based on 18T 12P)
I said "should", because I won't be certain until we've established how many poles there are.

(https://i.imgur.com/MbOa0gx.jpg)


Btw, you want as much copper as possible (read thick wire) to get the highest efficiency. Ohmic losses suffer with thin wire.


Just to show that with PM synchronous machines, there can be more poles than teeth;
This paraglider motor that I've designed and built has 24 stator teeth and 32 magnet poles.
Max power: 10kW
Phase termination: Delta
Propeller size: 1.2m - 1.3m

(https://i.imgur.com/0pX50RK.jpg)
Title: Re: flywheel rotor modification / repairing
Post by: The Buddha on August 09, 2020, 03:16:39 PM
.........Ask our mutual buddy Ken  :)




I've been bugging the Ken doll on unrelated issues and trying to pester him to coming over and building some stuff for me. Will see if he does ...
Cool.
Buddha.
Title: Re: flywheel rotor modification / repairing
Post by: sledge on August 10, 2020, 02:48:32 AM
I was last talking to him a couple of weeks ago.......ask him if he has got his `concrete` worktops in yet  :thumb: