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850 Starter motor refurb

Printed From: - moto guzzi forum
Category: Technical
Forum Name: Big Block Tonti
Forum Description: Spada, Le Mans and Cali
Printed Date: 29 Oct 2020 at 23:36
Software Version: Web Wiz Forums 12.03 -

Topic: 850 Starter motor refurb
Posted By: TheWrongTrousers
Subject: 850 Starter motor refurb
Date Posted: 08 Feb 2020 at 09:02
Morning all. 

Last time i ran my bike last autumn, i had to get a push start from a guy at the petrol station. Very slow starter motor could not turn the engine. The battery is good and the brushes on the alternator are new.

Embarked on a quite a big gearbox/clutch examination over the winter so the starter motor had to come off anyway. So now i am turing my attention to the Bosch starter motor. I am thinking that a good clean up and replacement brushes may be the answer.  I found this video which seems very helpful." rel="nofollow -

I would be interested to hear anyones views on what the guy says, or indeed if any of you have any words of starter motor wisdom before I start undoing bolts and embarking on another voyage of discovery. 

Serenity Now !!*!**!!

Posted By: Brian UK
Date Posted: 08 Feb 2020 at 10:08
The starter motor he uses will not be the same as yours as that one has permanent magnets, yours will have field coil magnets, so the brush layout may be different.

Take it apart as he showed and clean everything, and check the brush length. Make sure the copper commutator isn't worn.
Often just a good clean up and a bit of oil on the bearing bushes will be all that is needed.

The brushes and springs that hold them against the commutator can be very difficult to remove, take care.

Alternatively most Bosch service centres will overhaul it for you.


Better 5 minutes late in this world than years early in the next.

Posted By: theone&onlymin
Date Posted: 08 Feb 2020 at 11:18
Like these guys.
No messing about, but you may have to come a wee bit north of the river.

UNISTART 331 Wick Rd, London E9 5DH 020 8983 9969" rel="nofollow -


Posted By: JayDee24ca
Date Posted: 09 Feb 2020 at 03:09
Check Greg Bender's webpage (thisoldtractor) for his tutorial on rebuilding the Bosch starter on his loop. It is pretty much the same as the 850." rel="nofollow -
John D.

74 Eldorado
74 Nuovo Falcone Militaire
79 G5
79 Convert
00 Quota 1100

Posted By: Ken-Guzzibear
Date Posted: 09 Feb 2020 at 11:08
look up local Bosch service centre mu local one did mine They charge way less than Guzzi for items like brushes and bearings .... of course if you know how to do the stuff it's fine 

The Older i Get, The Better I Was

Posted By: TheWrongTrousers
Date Posted: 09 Feb 2020 at 17:13
All things considered, I think I will pass on getting stuck into this which after having viewed Greg Benders photo's (thanks for putting up that link JayDee) strikes me as a trip to a world of pain. I have decided to take Min's tip and get on the bus to Hackney with my starter motor, give them some money and let them do it !

Thanks all, as ever - for the sound advice !

Serenity Now !!*!**!!

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