SOHC.co.uk Forums > CB350/400

Starter Motor Not Working

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Drew400:
Hello all,

As my previous thread (http://www.sohc.co.uk/index.php/topic,7852.0.html) was leading this way, I thought I'd start a new one to make future searching for anyone a bit easier.

It seems that my starter motor is dead.

Step 1 - My meter is showing 12v from the solenoid when I press the starter button so I have removed the starter and now require your expertise (having never before stripped a starter motor).

Step 2 - I put a car battery between the body of the starter (-ve) and the power lead only to see a flash and no movement from the cog end before I rapidly pulled it away again.

Next step, removed the bolts to reveal the innards, as per the pictures below. A couple of things struck me: 1) should there be sheathing on both of the wires leading to the brushes? 2) I picked up a loose piece of metal that you can see resting on top of the body near the unsheathed brush. Can't see where it might have come from.

Any advice (such as buy a replacement starter motor!) very much appreciated.

Cheers, D.

tom400f:
I imagine the unsheathed brush is the -ve one and therefore that's OK.

You can check for continuity between the +ve terminal and the sheathed brush, or more importantly no continuity between the +ve terminal and the motor body.

Don't know what the mystery piece of metal is.

mike the bike:
It looks like a bent commutator segment bur I assume the segments are all OK otherwise you would have spotted it.  Brushes look ok though.  I'd give it all a good clean up and it might make sense

Lobo:
Hi Drew,

Starter motors generally robust bits of kit that rarely give trouble.... bad luck! 

That bit of 'swarf'... if its not obvious then perhaps a chip off one of the body magnets... they are brittle & can chip. Do have a good look around - there may be more awaiting their freedom.

Agree with Tom on the sheathing issue.

(1) Your meter showing 12v off the solenoid does not imply that the solenoid can supply the 80 or so Amps necessary to spin the stater. The weeny horn switch too will show 12v coming out of it ... but no way would it supply the starter. Point is... it may indeed be the solenoid is 'worn'. To check this I previously suggested you held a big screwdriver across the solenoid 'big' terminals ... (ie bypassing the solenoid workings)... if you did this, and no spinning, then indeed it points to a fault in the starter motor, its earthing (& battery too), or main +ve lead supply.
(Presumably you're 100% happy with all the wirings, crimped connections & ALL earthings.)

(2) Yup... always biggum sparks.... even with a healthy motor. I presume before you did this, that it turned freely?  Point I'm making is did you give it a 'manly' connection before bottling out due that big spark. (no offence Julie!)

As Mike the Bike suggests, I'd just clean it all up & put it back. Try putting the spindle in an electric drill, and on a lowish speed, and with some fine emery paper / 1200 grit whatever, gently polish up the commutator. Then with a soft pick (eg wooden toothpick) scratch out all the embedded (soft) carbon from all the 'slots'. Clean all aspects of the brushes / mounts, then grease all spinning bits  all up lightly & reassemble.

I've not checked (Honda) ... but recently bought 2 pattern starter motors for my Seadoo jet boat. Came in at $49 USD each.... wow, what a bloody bargain. (they were beyond repair due seawater)

Bryanj:
Not sure on extra metal but if it was inside it has to have broken off something which is worrying, Commutator (copper segmented bit that brushes run on) looks overheated to me and is one of the worst Ive seen also brushes seem worn odd.

Conclusion, good used part is probably cheapest and easiest fix

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