yeah, a bit fragile... im sure the rotor was having a laugh :)

mild steel would be fine, but at least 10mm thick, and M12 fine pitch bolt/nut in the center.
have someone make you a little bronze or copper cylinder to press on the shaft, make sure it has a small cavity on one side so the push bolt doesnt slide off.

put a loop of rope around one of the pull bolts so the rotor doesnt fly when it releases

sometime what breaks the hold is simply hitting the steel plate from the side

god is in the details,

You need something strong.

Mild steel will be strong enough if thick enough. Or shaped. You know where your current one bends - those are the places that need more strength.

The cheapest and easiest way is some scrap mild steel .. probably 10 or more mm thick. If you get special steel that will probable be good enough but then you have to put holes in it - need good drills etc. Easier, simpler and cheaper with mild steel.

Don't forget use the hammer thump on the central bolt - particularly when you have it under strain- it should just provide that extra bit to get it off without yet more strain on the jig.

IMHO unless you've got the bits lying around in a scrap bin and can make the puller in an hour or so it's not cost effective to diy it. If you have to buy in bolts, drill bits etc, spend time making the puller, then find it's not rigid enough so you have to start again with bigger bolts, thicker plate etc it's easier to either buy the puller or pay the local bike dealer to do it.

I've got at least three examples of lashed up pullers lying around the garage that have bent under the strain, had reinforcing lugs welded on, bigger bolts threaded into them etc and still not worked. They just get thrown into the corner and abandoned and when I (reluctantly) buy the official puller it does the job in seconds. I agree it comes hard to spend the money on something that you only need for about 10 seconds and is then redundant but there are times the you just have to accept that's how it is.

Just as a reminder though, sometimes the puller does work on its own but puller plus heat plus tap stands a better chance.

I totally agree with you on that. If I'd known what I know now when I started on the rotor I'd have bought the Kedo tool. But now I've spent money and time on doing it myself so it's become personal between me and that rotor. I can't back out now :-)

Just saying .................
 

................. some of the terminology within earlier postings here tend to confuse the structural/mechanical engineering terms "strength" and "stiffness".

Your current home made effort requires stiffening (via additional material added to the main plate e.g. by welding or bolting on an additional plate or other steel section).

It is probably adequate for the strength parameter.

Making a flywheelpuller is one of thoose occasions where overkill is barely enough.

I was just pulling the rotor off a kickstart only xt600 55w, yesterday, and my puller (actually my friends) had holes on wrong places, so rather than drilling new holes, I used an old magneto as a puller, and it worked perfectly :)

neat :)

I built one for my 3TB's out of a 5/8 thick stainless disc (what was easily available) about 5'' dia. and welded a 5/8-18 nut to the canter, then tapped the plate to match the nut for using a standard gear puller center rod . I then drilled the 8mm hole pattern for the flywheel on the mill and got 12.9 grade bolts 8 x 1.25 x 100mm IIRC . Didn't know if the 12.9 where too brittle so also had 10.8's on hand , didn't need them but probably all I needed.https://www.mcmaster.com/#91502a210/=1a7kvbc

A person must make sure the 8mm bolts are perfectly straight(thus the holes drill right) and everything centered so the puller of pulling as straight as possible . I have pulled several now without much trouble . I just get it setup and use an impact driver start tightening the 5/8 rod while hitting the side of the flywheel using a lead hammer (to not damage the flywheel). They've all popped off before the impact really gets to the full torque. Care is a must to protect the crank end and use more than enough antiseize on all threads and where the center rod spins on the crank end if not using a rotating version (but it also should be lubed inside the tip).

.

Well the rotor is finally off thanks to all the generous help I have help on this thread (a metre long pipe on the spanner was the deciding factor). But with all the heat I used something seems to have melted out from between the wall of the rotor and the back plate. I've attached a pic of this black gunk. Can anyone tell me what it is? And have I destroyed my rotor?

http://www.horizonsunlimited.com/hub...1&d=1511879896

Rotor removal
 

Hi Connal, That looks like the 'glue' used to hold magnet segments inside the rotor, cooked out from heating. It may be unsafe to try using it again.

May i advise that heat is something to avoid if at all possible. And then a rapid application with a large torch, like from an oxy-acetylene cutting torch. For seconds only. If it fails to dislodge, leave everything to cool before another attempt.

Note also how the puller design can get in the way of heat source. The design in Kedo's catalogue is best. It allows access and does not trap the heat inside the 'drum' that the rotor resembles.

Something to consider is the value of the 'tap' applied to the puller bolt. With a sturdy puller well located and 'tight enough' and a hammer of 'suitable mass', and 'struck smartly' will do the trick. Especially if the crank has some end play and you pull it toward you before applying the tap. It's in the relative masses and acceleration of the crank in relation to stationary fly wheel. The crank is way heavier that the rotor, so a light hammer will be useless. Experience is a hard school.

Also watch out for delicate parts behind the rotor can be damaged with too long bolts used holding puller thru' the three 8mm holes.

Last but true; don't overtighten, use a torque wrench and correct specs on this and most fastners. It will make it easier the get off next time

That's it. All the best getting it back together.
p

Wow that sounds like very bad news - MSP want more than 500 euros for a new rotor. Thanks for the advice though, it should save me making an expensive mistake next time. When you say it may now be unsafe do you mean it is just likely to fail at some point or could it now make the bike dangerous to ride?

Yamaha XT600 Magneto Flywheel Fly Wheel 3TB XT600E Electric Start | eBay


Freeze spray or upside down compressed air can, spot heat area and keep area around cooled down. It doesnt take much heat before glue is damaged. In this case i would use a cold wet rag around + freeze down.

I was sure this thread was already here http://www.horizonsunlimited.com/hub...r-clutch-53329

It should be fairly easy to get a used flywheel for cheap since they don't really go bad like other arts even on higher mileage bikes . The heat can also reduce the magnets power so it'll have weak spark , best to replace . I've never had to use heat on any of mine , impact on the puller and firm hammer hits pops them off .




.

i have a rule when using a propane torch, no more than 60 seconds application. guess it happened when you were using the weaker puller...