Rotor removal
 

I'm prepared to get shot down in flames here because this could be a very stupid question but is there any chance the rotor/flywheel on my 1997 XT600 could be threaded? I ask because it refuses to move despite me following all the great advice on here about using heat and a hammer with a pulling rig and protecting the end of the crankshaft. But when I look at the image on the parts page on MSP (shown below) it seems to show a thread pattern inside the central hole. Is this some kind of stepped taper or could it be thread?

If not I’m guessing I need to heat it more or hit it harder – can anyone tell me which is least likely to cause serious damage to the bike? I’m concerned that too much heat might deform the rotor or cause it to blue.

http://www.horizonsunlimited.com/hub...1&d=1509193258

Not threaded.

A friend of mine had one that really had to take a beating with a big sledgdehammer, if flew across his worshop when it let go.

With my own, i just put some tension on the puller, gave it a few whacks, and repeated that 2-3 times, and of it went. I was really surprised at how easy it was. So its very different from bike to bike.

My guess is that a good puller, with even tension so its not pulling slightly "sideways" will help alot.

No, not threaded, it's a taper fit - basically jammed in place with a nut to stop it coming off. If the male and female halves of the tapers are a good fit (as they should be) it can sometimes be a real struggle to get them apart. That's where the heat idea comes in - if you can get the flywheel warmer so it expands it'll release its grip on the shaft slightly (until the shaft heats up). You don't need to get it glowing in the dark but hotter than touchable should be somewhere about right. Remember it gets hot every time the engine runs so it's designed to take a bit of heat.

I've rarely (read never) had much luck with the two or three legged type of puller on flywheels. For what the proper puller costs it's worth buying one and even then it's sometimes tough (or it'll fall off straight away!). Heat it up, tension the puller (protect the end of the shaft with a sacrificial nut) and if it doesn't come off tap the end of the puller with a hammer. That's tap, not breaking concrete with a sledgehammer.

If you've got to this stage and everything is under tension do whatever you have to from the side, not in the direct line of fire if the flywheel comes off. The rear wheels of one of my cars are held on by the same method except everything is twice the size and they're always tough to get off. I've had the whole hub and puller assembly fly across the garage with some force before now. If you're in the way it'll hurt.

Thank you for the advice guys. The puller being to blame is something I hadn't considered enough, but it makes sense. I'm using a home made puller (now on the third version after the thread stripped on the first one and the plate bent on the second) that fixes into the threaded holes kindly provided by Yamaha. I've tried to keep it parallel with the rotor but I guess if it is even a few mm out it could cause one side to bind on the shaft. I'll make a stronger v4 tomorrow. It's good to know I'm not fighting against some high tensile thread through.

Be carefull when you tighten the puller, I always meassure the distances on four points from magneto to puller, up to 0.5mm accuracy should be good enough.

I wasnt carefull once, and new crankshaft had to be ordered doh

Wow. I've been working on anything within 2mm being good enough so that could be where I'm going wrong. I'm thinking that my homemade rigs are not good enough and I should invest in a proper good quality puller, preferably one I can use for other jobs on the bike like splitting the crankcase. I'm seeing 'harmonic balancer pullers' on ebay that look like they will do the job but all seem too cheap to be any good on a job like this. Can anyone recommend a quality tool that is likely to last? The Yamaha one is stupid money at 150 euros plus, especially as it only does one job.

KEDO - Performance Products item no 30270

KEDO - Product Details

Had a friend who built a copy of this, and the copy was great (it was the one I used) so id guess the original would be too =)

How frequently are you really likely to use it?

If it is very seldom then could you hire it from the local Yamaha workshop? OR if forced .. take the engine to the workshop to have the flywheel removed.

A tip when refitting the rotor.
The taper on the crankshaft and inside the rotor must be dry when refitting.
If there is oil or grease, the lubricant will allow the rotor to be pulled on further than it should be, and become tighter on the taper, making removal next time more difficult.

Bob

Oil or grese could also be the cause of spinning the flywheel and breaking the key.

So make sure everything is clean and dry, an torque down properly!

When you're refitting it the two halves of the taper must be a good fit. It doesn't take much - a slight burr on the metal or a bit of grit - to stop the two halves mating properly and you'll run the risk of the flywheel moving. It's the metal to metal contact that stops the flywheel spinning on the shaft, not the metal woodruff key. That's just there to make sure everything goes back in the right position.

If there's any doubt then lap the two together with some fine valve grinding paste. You'll very quickly see which parts are in contact and which are not.

guys, thats plain cruel, he can not take it apart and you are telling him how to put it together? :)

here's my tool
important to use a fine pitch M12 bolt, a coarse pitch will generate less pull
distance between M8 bolts is 75mm, just draw a triangle with a compass

Haha thanks turboguzzi. That tool looks great compared to mine (pic below) and made me realise I need to make a much stronger rig. Mine uses 8mm threaded rod which is distorting under the pressure and two bits of 3mm plate which are bending outwards.

This is a tool I want to have because I'm having so much fun learning how to fix this bike that I'm sure there will be another in the garage as soon as it is finished. But I'm reluctant to spend the 52 euros on the Kedo one and concerned that the cheap Yambits one might not be up to the job. So I've ordered some high tensile bolts and now just need to find some steel plate. Is yours mild steel or do I need something special?

And thanks guys for all the advice about putting it back together - you saved me making some costly mistakes because I had imagined it would be a straightforward case of just whacking it on and tightening up the bolt.

http://www.horizonsunlimited.com/hub...1&d=1509447968

Huh, this is seriously "lightweitgh" puller :nono: Not sure if this would even take it off mine 50cc scooter :smartass:

You need a lot stronger stuff, I used 10mm thick steel, ok I am maybe going a little hard, but it has done the job easily a few times. I'll take a pic later.

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).

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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 .




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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...

Yeah I think so. I was giving it several minutes of heat at a time. When I used my new improved puller with some long bars for leverage it came off with no heat or hitting. Another one of those learning from experience occasions I guess. beer

Coming a bit late to the party here, but the thread you can see in the parts diagram looks very like the thread in a Yamaha TTR 250 flywheel, and you use this to pull the flywheel off by winding a special bolt (or the rear wheel spindle, which is the same thread) into it, which pushes against the end of the crankshaft.
Glad the job is done anyway.

I just removed my rotor with the Kedo puller, it came of effortless.
Once again, I highly recommend this.

Slightly offtopic, but I figured you guys would still appreciate it. :innocent:

This is why I removed my rotor. 800gram removed from the flywheel/starterclutch, was done over 2 times, but heres the final product. Still more weight to be removed, but we stopped here.
Hopefully this will remove some of the felling of dragging an achor in a bungy cord behind the bike http://advrider.com/styles/advrider_smilies/lol8.gif
http://www.tenere.dk/forumnew/uploads/987/Flywheel1.JPG
http://www.tenere.dk/forumnew/uploads/987/Flywheel2.JPG
http://www.tenere.dk/forumnew/uploads/987/Flywheel3.JPG

Hehe good luck!:scooter:

Good carbs with an accelerator pump gets rid of that bog/lag/hesitation a person feels on these bike . Higher comp helps as well .

The 660 Raptors have a considerably lighter flywheel(and smaller dia) , they rev to 9k easily (but won't live long if let there ). These motor aren't tight enough tolerances to spin like that , but the heavy flywheel is what lets them sit at 60-70mph effortlessly , something I can notice the 660 doesn't do as well .


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Have made a new topic regarding reduced flywheel weight :D