Starter motor brushes, 2 or 4

[Steve M]

I think I've seen discussion on this topic before but can't find it. I am working on a Z1100 shaft with a lazy starter. It has 2 brushes and 4 magnets. Could I replace the 2 brush plate with the later 4 brush version or are the windings different for the two types? many thanks for any advice.

[Al]

I would be surprised if any parts are interchangeable between 4 and 2 brush set-ups but you never know.
Perhaps the easiest thing would be to source a good 4 brush motor and re-furb it or yours because the standard system doesnt struggle therefore something must be amiss.
A really good clean up in the hands of someone who does that sort of thing should sort it all out but after 40 years plus, the supporting ancilliaries may be the issue.
I would replace the battery cables and the lead from the solenoid to starter and from engine earth back to the battery with new stuff.

This works best as it has better density per unit of cross sectional area..
https://www.vehiclewiringproducts.co.uk ... rter-cable
They do black and red and some pre-made to lengt options too with terminals readily done.

New brush kits may be available for what you have now like one of these perhaps.
https://www.electrexworld.co.uk/acatalo ... s_720.html
The 4 brush plate is a drop in, dont know about the two brush item.

Solenoid may be gone high resistance so one of these will do as a replacement.
https://www.electrexworld.co.uk/acatalo ... ml#SID=726
Its not the only option but i have had one of these for eight years trouble free and the standard one was about £90 or something stupid like that.

Finally the battery CCA may be holding it back.
I assume its in good order but if it isnt then a new one with better Cold Cranking Amps may help.

AL

[Steve M]

Thanks Al, that's really useful info.

[Al]

Forgot to mention; one 'constant' (see 'constant pain in the f&*^i&g a&*e') is the point where the earth return runs from a tapped hole on the back of the crankcases to the battery. Where the ring terminal bolts on there, it builds up a layer of aluminium oxide and annually i have to scrape it off or it wont run the starter motor properly. I have a sharp, broad bladed flat screwdriver which i use like a wood chisel to gently plane off about a few thou of crust. Its like kettle scale and it gets on there like nobodys' business.

AL

[gray]

if you used a little dialectic grease there( ie electricity- conducting) after doing your yearly scrape then that might slow up the oxide reforming between the crankcase and the ring terminal

[Al]

Thanks gray, its on my list.
AL