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Armature removal

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There have been a lot of older bike strip threads started recently so I thought I would post about the old skool armature removal. The armature is a wire coil that forms part of the generator/starter.

The part is generally held in place as a press fit on the end of the crankshaft and has a woodruff key to stop it spinning. A bolt may or may not hold this is place but the armature will be a very tight fit and will not just pull off.

Yamaha have a special tool to remove them however, they do seem to be scarce (unless people know better?). The only one I can see for sale at the moment is here LINKY This is for a couple of specific models and I am not sure how universal they are.

Without the special tool, it seems that it is not too difficult to manufacture one. The problem is that you will need to use precise materials. You may get away with a bolt and a cut down drill shaft provided they are glued, welded, or otherwise fixed together. Otherwise you will lose the cut down drill inside the armature itself.

The important part

Looking at the YA earlier, it seems that the most important part is to make sure that the bolt you use is of the correct material and of good quality. The armature has a thread that is used to tighten the removal tool. much this up and you may never get the armature off without breaking it. The YA armature has a standard M8 thread. I took a few M8 bolts to mine this evening, many I could wobble into the threaded hole. Only 2 actually tightened up. The best one was one that came with an ABBA stand accessory. All fitted the same nut so there are some huge quality issues with some bolts.

My armature is still on the bike. I ordered a blind bearing puller earlier and will see if the 8mm thread off one of the collets is up to the job. I intend to pull mine off.

Oh, one last thing, don't drop it when it pops off.

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This is odd .... back in the day to remove an armature (DT125E/RD200) we used the Yamaha special tool (slide hammer) however other models used a hardened bolt, which after it was screwed into the rotor (armature) until resistance was felt then it wss shocked with a hammer and then tightened until the rotor/armature was released from the crankshaft taper & woodruff key

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