starter motor for a norton commando

[allan the bus driver]

well I got fed up with the last person to do the starter (2 brush to 4 brush) motor brushes I got it back from him ordered some longer tail's on the brushes and done it myself after quite a lot of fiddling about it work's, The only trouble is there is not enough power going through so I'll have to dismantle and put the other set of field coil's in,So my answer is if you can't do it have a try.
I thank you all for your help and advise and the photo's were a great help as well
                                    Once again thank's very much
                                                Allan

[L.A.B.]

To be honest, the 4-brush (with 2 field coils) conversion doesn't add much in the way of extra cranking power to the Commando starter.

But with a fully charged battery in good condition and with a set of heavier gauge starter cables that should be enough to spin the 850 Commando engine over at a decent rate. Replacing the old Prestolite solenoid with a Lucas type car solenoid can also help.

[rogerwilko]

And make sure there's no play in the end bushes or you're wasting you're time. I think there is a ball bearing conversion using Harley endplates.

[Gromit]

Little history

The Norton Commando electric starter was made in the USA by Prestolite and was a cheapo one purported to be used to start lorry fridge compressor engines, hence the 2 brushes and 2 field coils ... what might start a 250 cc single fridge compressor engine a'int never going to reliably start a high compression 750. Even Joe Lucas realised they couldn't do a motor at Nortons budget price, hence the cheapo yank one being used.

People found that Harleys have the full motor with 4 brushes and more coils and seem to start OK ... but they have a big battery and cable 'cos everything is built like a brick privy on a Harley ... well except the bits that matter... so as L.A.B. says beef up the cables and if you can enquire from a good battery place to see if there's a bigger cranking capacity battery that will fit in the Commando batt carrier consider going for it and it will work .. he says encouragingly.

Oh and make sure the solenoid is a good one as high resistance across the main contacts of just a bit is enough to rob the starter of a couple of volts. Another trick is if you can use one that you can get at to press it in it may start better as you will not have the solenoid magnet coil to supply and all the current goes to the motor instead. Sort of electric start but not quite that suggestion

Regards Gromit