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1975 Honda CB360.blog

CB360 Starter Motor Rebuild

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Honda CB360 (and many others) starter rebuild

Seeing as how I have had this bike on the road for a few years now I figured it was about time to fix the electric starter.  I don't mind kick starting it as it usually starts on one or two kicks but sometimes I think it would be nice to just push a button and go!

This is actually the second starter I tried on this bike.  The first was toast when I bought the bike.. I took it apart to find the bearings ground out of it.  Probably salvageable but I decided just to get a used starter from ebay.  Well, the second one I bought was really weak.. worked for about 2 weeks and then it was finished.

I finally cracked it open to have a look inside.

Here is the starter broken down into its main components.

IMG 5989


The brushes were a little rough but there is plenty of material left to work with.  I will clean these up and re-use them.

Inside I found that the rotor had been coming in contact with the stationary magnets because of a failed rear bearing.  This would cause the rotor to lock in place any time the motor was energized. Though there was some scrapes on the rotor and the stator magnets all the windings looked intact. The brush contacts are also pitted and worn. Most likely there was accelerated wear in this area due to the slop in the rotor bearing. I will lightly file the contacts and clean them up without removing too much material.


Here is an up-close look at the failure point. Seeing as how this is the second starter I have had that failed in this way I would assume this is a problem with all these starters.

The shaft at the rear measures just under 9mm in diameter.  It is very pitted but I don't think much material was lost, it seems that almost all of the wear was too the sleeve bearing itself which is a good thing.

Since this bearing was pressed in blind I had to drill out the back to press it out which I will later cap once everything is re-assembled.

As you can by the measurements of the shaft and ID of the bearing there was quite a bit of slop. 

Since the shaft is very rough I will be replacing this bearing with an equivalent ball bearing which should add a lot more durability as well as a lot less drag on the motor.

The sleeve bearing size is 9mm ID x 14mm OD x 8.4mm thick and had a 1mm oil baffle behind it.  Total depth of the bearing holder is a little over 10mm.

I was able to find a common ball bearing size of 9mm x 14mm x 4.5mm I will use two of these side by side for a 9mm x 14mm x 9mm dual bearing setup.

The end cap is sealed with a rubber O ring shown below.



The front cap contains a planatary gear reduction set which can be removed as one unit.  The the planatary gears can then be removed, but output shaft is held in place by a snap ring on the front.

The front motor cap and bearing can then be removed. I accomplished this by slightly tapping the back end of the rotor shaft on a peice of wood.

Both the planatary gearbox and front motor cap are sealed by gaskets. 

Don't loose your thrust washers! Two in the back and one in the front.  By their size its evdent which go where.

The front bearing shows no wear and will not be replaced.




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