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Because it’s impossible to get my R30 back into my garden without engine
power; I always do a quick start up check before rolling down the steep slope
that leads out to the road, recently this proved to be a good idea when my
starter motor failed.
Luckily I worked in the motor trade when I first left school; and following that
period I took a career change and I have now worked in electronics for over 35
years, needless to say the inside of a starter motor is something I have seen
before.
First off I put a voltmeter on the motor positive terminal to check for the
presence of 12 Volts when the starter button was pressed, the starter solenoid
clicked and sure enough up flicked the meter, not a murmur from the motor, when
you do this test put the negative lead on the motor body to ensure you don’t
have an earthing problem.
Removal of the motor on the 644 R30 entails removal of a number of other bits
first, the procedure is detailed in the XF650 manual but briefly the parts are,
exhaust complete, oil pipe disconnection at two points, disengagement of the
clutch cable at the lever and removal of the timing chain tensioner. To get at
the top oil pipe connection I found it easier to remove the seat and petrol tank
first, it’s such a quick job anyway.
Worth a mention is refitting of the timing chain tensioner, you can’t just push
it back in against the spring pressure so it has a mechanism fitted to help you
refit it. There is a cap screw at the back of the tensioner which when removed
gives access to a spring pre-tensioner, this is a screw which you wind down
until it latches at the end of travel. After the timing chain tensioner is
refitted you re-insert the screwdriver and release this mechanism.
Once you have the motor out it may be obvious that water has got in, there are
two “O” rings sealing the main casing and in my case the front ring had allowed
water in. At this point it would be a good idea to study the starter drawing
supplied on the CCM web site, see copy below here.
Before opening the motor take a look at the main casing and you will see two
alignment marks which line up with marks on the front and rear case ends, you
will use these during re-assembly.
Its now time to remove two long screws (9) and open the motor, when you do this
try to make sure you keep the two “O” rings with the appropriate case end as
they may be re-usable and like mine may have been compressed to different
thicknesses.
There are a couple of groups of spacer washers (7) on the drawing and as long as
you are careful they will probably stay in place throughout any repairs, with
the possible exception of the front bearing retainer (the one with the lugs).
Pull off the rear cover first and check for ingress of water, it may be that
it’s dry and you just have failed brushes, either way you will probably need to
replace the same parts. Unfortunately none of the drawings I have seen correctly
illustrate what parts you get as assemblies, in simple terms if you have a
corroded brush holder or your brushes are badly worn you will need to order two
parts, more if your “O” rings are shagged (technical term, sorry).
Ok these are the two main parts which you can get from
Robinsons Foundry, (1)
part no. 31132-38B00: Brush Holder Set, this comes with the two negative brushes
fitted, (2) part no. 31130-38B00: Brush Holder Set comes with a plastic
retainer, two positive brushes and new terminals. See photos.
New Holder 31130-38B00
Corroded Holder 31132-38B00
Plastic Retainer supplied with 31130-38B00
You should be able to see the old carbon
brushes firmly seized into their rectangular receptacles in the right-hand
picture, normally these pop out with spring pressure when the rotor is removed.
At this point you will need to remove the front motor cover, this cover houses a
roller bearing which is normally lubricated by the engine oil, there is an oil
seal inside to prevent oil getting into the starter motor, it would be wise to
remove this cover carefully so as not to damage the seal, again try to keep the
“O” ring (8) with the front cover.
You now have the centre of the case with the rotor still inside, take hold of
the splined drive shaft and against the magnetic force trying to keep it in the
case you can withdraw it. The copper segments (Armature Contacts) at the rear of
the rotor will probably be sooty and black where the carbon brushes have been
sparking prior to failure, this can be carefully cleaned before re-assembly with
very fine emery and washed clean with spirit.
Rotor showing Armature Contacts to the right
Part cleaned contacts showing black sooty deposit
Don’t panic if at this point the carbon brushes have all fallen out; all the
bits have got to come out and go in the bin eventually anyway, just take care of
any washers on the rotor; as I said before you can just leave them in place.
Next you can remove both brush holders, the circular plate has lugs at the edge
and these just sit in recesses in the case and plastic retainer, undo the
positive terminal nut(s) and washers, keep the nut that normally holds the 12
Volt feed in place and bin the rest. Ok now you can just pull out both holders
and remove the plastic retainer from the case, now have mug of tea and a bacon
roll.
This is where you do all the cleaning and I don’t propose telling anyone how
well you need to do that, make sure the case “O” rings have a nice surface to
seat on during re-assembly and take care with the copper rotor segments.
Here is an opportunity to come up with a way of keeping the brushes back in
their receptacles against spring pressure during re-assembly, remember they are
soft carbon and to handle them gently. A suggestion and this is the method I
used, one at a time secure each brush into the receptacle with a very small
cable tie, it’s still a bit fiddly when you try to push the rotor back through
but it can be done. In theory you could pull the brush springs back and secure
them to take pressure off the brushes, I thought there was a chance of damaging
the springs, you will find a way.
Assuming you have the right parts and cleaning is complete you can start to
reassemble the motor, first fit the black plastic retainer into the rear end of
the main case, it’s a push fit and easy to align by sight. Next the positive
terminal with brushes is push fitted into the retainer, but before you do; it’s
worth offering up the circular brush holder to see which way round it goes; in
fact check lug positioning and you will see it can only go in one way.
Now you have the positive terminal and brushes in the plastic retainer and you
are offering up the circular holder with negative brushes, it should be looking
like this:
Take care when threading the yellow sleeving from the positive brushes through
the holes at the edge of the circular brush holder; you will have a problem (big
bang and smoke) if the brush wires make contact with the holder.
Once you have both holders seated you should fit the new washers and nuts to
secure the positive terminal. Using your chosen method all four brushes should
be fitted into the appropriate receptacle and fully retracted, note that they go
in from the front and the wires are not long enough for you to fit them in the
wrong place (famous last words). Now the rotor can be inserted into the front of
the casing; again by holding the splined output shaft, the magnets in the case
will try to pull the shaft into the case so restrain it slightly because you
have to carefully pass the armature contacts through the four brushes, it should
look like this:
Nearly there, it’s time to fit the case ends and finish assembly, if you are
sure the “O” rings will seat properly then go ahead with the rear end case
first, remember there are marks to help you align the two parts, personally I
used a preparation to assist with sealing but you will have to choose whether to
or not. Now the front case end, same story as the rear; just ensure the splines
don’t damage the front end oil seal, that’s it bolt it together keeping an eye
on the “O” rings and Bobs your mums best friend.
All procedures described in this document are based on personal experience, use
of the correct tools and suitable test equipment. When installed in a motorcycle
engine the full 12Volt supply is applied to the motor and at fairly high
current, if you are unsure of your capability in carrying out this work you
should not attempt it.
If you damage yourself, your starter motor or your motorcycle then it will be
your own fault.
Alignment Marks – Case Front
644 Starter Motor
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