Starter motor issue

[ontwowheels 19]

More amusing than anything else. New (to me cbf125). Started ok but sluggish for a week, then nothing. Tested stuff through to the starter motor, and once off the bike it was obvious it had jammed solid. Got it apart and one magnet had come unglued from the casing and had broken in two.

 

No problem I thought. So I removed the other part of that magnet, and the other magnet. Cleaned the casing of old glue etc, and re-glued both magnets. After a right faff with trying to get the brushes back in, reassembled it all and.....it now spins the wrong way! Even when connected to a car battery off the bike. I'm sure I can't have messed up the wiring in the motor - I don't think it's possible to reassemble that bit wrongly. All I can think is that the magnets have a N and S and somehow I got them upside down or something. Could that be the issue? I don't think I can unglue them now so may have to get a complete new motor.

[Johnnie Mototrans 2,773]

Are you sure you connected the car battery the right way round?

Also what have you observed?

Remember the starter motor will be geared and is likely to turn in the opposite direction to the engine.

Did the bike engine actually spin backwards?

[ontwowheels 19]

Thanks, and yes, battery absolutely connected the right way round (repeated many times). Also spins backwards when connected and fitted to bike (the battery of which hasn't been disturbed, and the connections to the motor can't physically be swapped over). No gearing in starter, and yes, it tries to spin the engine backwards (although there appears to be a simple "freewheel" or clutch on the bike which means the engine doesn't actually spins backwards).

 

I can get a S/H starter for about £15, so might give that a try.

[davebike 943]

You have not got the magnets in the right place or orintating  Had a rewinde company do this to us 

Mostly not fixable  get another starter used or pattern

 

 

[Xactly 5,499]

I’ve had a 6volt Lucas dynamo reverse it’s polarity of its own accord. It sucked all the smoke out of the battery. There was a procedure to rectify it. As you probably know a dynamo and a starter motor are essentially the same thing; off the bike if you connect a dynamo to a battery it will motor if it’s ok, one of the tests for an apparently duff dynamo.

It’s likely that the pole magnets have not been correctly replaced or have reversed polarity but anyway I doubt that the fix, even if it were to work, would last long.

[Zalman 4]

Invert wires on brushes ?

Edited March 23, 2022 by Zalman
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[ontwowheels 19]

Thx again for the replies. There's no reasonable way to adjust the wiring inside the motor i.e. to the brushes - at least not with my skill and tools. I have managed to pick off the magnets and turn them both top to bottom in case it was a polarity thing - motor again spins nice and powerfully in the wrong direction. I've given up now and ordered a second hand one - defeated.

[Johnnie Mototrans 2,773]

2 hours ago, ontwowheels said:

Thx again for the replies. There's no reasonable way to adjust the wiring inside the motor i.e. to the brushes - at least not with my skill and tools. I have managed to pick off the magnets and turn them both top to bottom in case it was a polarity thing - motor again spins nice and powerfully in the wrong direction. I've given up now and ordered a second hand one - defeated.

 

I think for £15 that's probably the correct answer.

[davebike 943]

Right move

The starter repair place we sent the one we had repaired to to sort running backwards said  not we cannot fix!

The recomendation seems to be if the magnets come lose new motor !

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