Author Topic: Rotor magnetism ^  (Read 113 times)

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Dibble

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Rotor magnetism ^
« on: 15 May, 2022, 11:04:02 »
Morning all,can any of you very wise and well informed people advise me as to when  a rotor requires re magnetising? I have purchased a new alternator for the Hornet but then thought what if the rotor is past its best! I can pick it up using a screwdriver and it seems quite strong. Any advise please. Dave.⁶

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Re: Rotor magnetism ^
« Reply #1 on: 15 May, 2022, 15:06:16 »
The test is if you can pick it up with a screwdriver then it's OK. So, looks like yours is fine.

Another thing to check for is whether the steel centre has come loose. They may look OK but the steel centre can move a few mm. To check, get some spacers or suitable size nuts to but up against the centre each side and clamp it in a vice. Grip the OD with your hands and if you feel a slight rocking then it's loose.

The problem is if its loose, it will oscillate at high frequency and the woodruff key will wear away at the keyway on the crankshaft causing major vibrations and worse, needing a complete strip to weld and recut the keyway.

Credit goes to Dave Smith (Rupert Ratio) for this tip in his Unit Singles Engine manual.

Dibble

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Re: Rotor magnetism ^
« Reply #2 on: 16 May, 2022, 14:07:06 »
Many thanks for that most useful information. Looking good re loose centre too! Great. Dave