Can't remove magneto rotor

[Magellan]

Gotta love old bikes....

Trying to get into the bottom end of a kdx80, but can't get the rotor off.

I have a puller and have tried tightening it, whacking it with a hammer, using an impact wrench, heating it with a torch, and nothing is working.

About the only thing I can think of at the moment is to separate the cases with the rotor on, and then put the assembly in my press and trey to press the crank out.

Not sure what that would do to the windings underneath and have some concern about damaging the case as the rotor would probably bottom out on the edges before the crank came loose.

So, looking for other ideas before I go that route.

Thanks,

mag.

 

[dirt bike dave]

Man, that is a tough one.

Basically the rotor has fused to the end of the crank over the decades. IMO, your best bet is the puller and tightening it a lot more than you should have to, and more than you think it can take. Hopefully it will pop off just before the puller's threads strip.

When the metals meld like that, heat does not seem to do much, and you will have a difficult time getting any liquid wrench or any other substance in there to lubricate or break the bond.

You can rewind the stator if it gets damaged, but you really don't want to damage the cases or crank. Not sure how hard it is to find a replacement flywheel/rotor for the KDX80. I'd sacrifice the flywheel before I risked the crank or cases.

Maybe you can lock the crank via the primary drive on the right side down, then spin the flywheel with an oil filter wrench or something like that? You will have to shear the woodruff key that holds the rotor in line on crank, but it might be easier to rotate the flywheel on the crank to break the bond, rather than pull if straight off.

 

[Rich Rohrich]

I've had exceptional luck over the years using Kroil in situations just like you describe. It works far better than anything else I've ever used.

I found that heating the metal a bit to get it to expand and then applying the Kroil and letting it sit works best. The trick seems to be getting the metal warm enough to expand without getting it so hot that it causes the fluid to evaporate.

http://www.kanolabs.com/penLub.html#anchor173855

 

[WoodsRider]

Been there, got that t-shirt. What I did was heat the end of the crankshaft to around 450 degrees, with oxy-acetylene and a rosebud, and quenched it with penetrating oil I had put in the freezer overnight. Then I threaded the puller onto the flywheel, tightened the bolt as tight as I felt I could get it without stripping threads and struck the bolt with a small sledge hammer. Took two tries, but the flywheel came loose.

 

[Magellan]

I'll try WR's suggestion this weekend. Gotta get a rosebud tip...

 

[RM_guy]

If that still doesn't work, try the Kroil. It is truly amazing and works quite well!

 

[Magellan]

Been there, got that t-shirt. What I did was heat the end of the crankshaft to around 450 degrees, with oxy-acetylene and a rosebud, and quenched it with penetrating oil I had put in the freezer overnight. Then I threaded the puller onto the flywheel, tightened the bolt as tight as I felt I could get it without stripping threads and struck the bolt with a small sledge hammer. Took two tries, but the flywheel came loose.

NO luck with my initial tries, though i didn't have the oil in the freezer over night.

Will try again tomorrow...oil's now in the freezer.

 

[WoodsRider]

Use the pour-type penetrating oil, not the spray type. Make sure the engine is on its side so gravity works with you. I used PB Blaster, but have heard Kroil works as good or better.

 

[Magellan]

I tried the spray, but I did have the engine on it's side and filled the space in the rotor.
I got the thing pretty damb hot. I think I melted the coills or seals...something definitly melted.

I have also mushrommed the crank end a bit. i thikn I'll e able to clean it up on a lathe if I ever get the crank out.

 

[WoodsRider]

I tried the spray, but I did have the engine on it's side and filled the space in the rotor.
I got the thing pretty damb hot. I think I melted the coills or seals...something definitly melted.

I have also mushrommed the crank end a bit. i thikn I'll e able to clean it up on a lathe if I ever get the crank out.

The problem with aerosol sprays is they can evaporate. You will cook the seal, but you were planning to replace that anyway.

I've heard of people using some sort of liquid nitrogen, that comes in a spray can, along with penetrating oil. I've never tried that though.

 

[Magellan]

OK, that explains all the smoke ;-).
I thought about using some of that air in a can. You can turn it upside down and the liquid comes out. I think it's just CO2. It's pretty cold, but not as cold as liquid nitrogen.
Didn't have a chance to get into the garage tonight. Maybe tomorrow.

 

[Magellan]

After three tries with heating the rotor and then pouring cold oil in the well, I still can't get this thing off.

I'm just about ready to try cutting it off, though I'm not sure what that'll get me.
I may be able to get most of the rotor cut off, but in the end, I'll still have the middle of it pressed onto the crank shaft. May careful work with a cutting wheel could do the trick...

If I cut just the sides, I may be able to get something under the top sureface of the rotor so I can press the crank out.

Still looking for ideas...and maybe a bit of emotional support...

 

[Magellan]

allright, I couldn't take it so I took a cutoff wheel to the rotor. What I should have done was grindoff the rivet's and popped the flywheel off. Then I could have put it back together. But I didn't think about that until after I had cut all around the flywheel. In any case, I was able to get down to just the core of the rotor that was on the shaft. I was able to remove the stator and then was able to heat up the core of the rotor that is on the shaft. It seems I wasn't able to get it hot enough with all the mass of the flywheel in place. Maybe if I had applied more heat, but I already had the crankshaft glowing and couldn't get it off. In any case, now it's off, but I need to replace the rotor. I think the stator is fine. I'll test it later. The crank end is mushroomed quite a bit, but I think I'll be able to clean it up enough to get a nut back on.

I'll post pics later.

mag.

 

[WoodsRider]

Wow, sorry my trick didn't work for you.