Here is and excellent book on motorcycle electrics buy it read
it and learn !!
Im going to collect info here on Refurbing starter motors for the Cagiva mito 125
I was hoping to do a full rebuild on this on but all it took was a bit of oil on the bearings and a good clean out and relube where needed .
But its quite easy to change the brushes and bearing on these stater motors and can save a lot of money .
Getting in is easy just three PH1 screws
here you see the brushes holder plate i cannot find these to but if anyone know let me
know and ill link to it . i use sizes 5mm wide 8mm high 15mm long
here im undoing the Brushes spring clip
one you undo the main positive side brushes you can remove plate
here are the positive side brushes the current goes thought the connector on side of
starter then through the field windings and then into the armature via the brushes
then out again via the opposite side brushes
the negative side brushes are on the plate
and although it would be easy to change plate fiding them are hard
i usually ......
Cut the old one off at spade connector then grind connector flat
clean surfaces and re-solder the new brushes to this connector
i did not have to do it this time but i will in the future .
To change the Positive side brushes you will need to remove armature and winding
undo all the securing screws
remove drive gear retaining clip and gear
armature will come out and then you can access the brushes
connector you need to clean and flux and then solder in new brushes
DONT FORGET THE INSULATION
thats all i have now ill update this when i do a full stater motor refurb and solder in new brushes
but have a go its quite easy .
Here are some brushes i use
and here are starter motors for sale Used .