Starter woes! Failure to turn over. Starter motor removal and repair.

Starting has always been a gamble for me; not motor-wise, that's always been fine, but its a big bike to bump- and at my age not a good idea to try! This means that in the absence of a kick-start you are reliant on the starter motor and its chain of components. 

I'm guessing we've all been there... operate the starter and nothing happens... well usually something happens but it doesn't result in engine turnover or motor start. In my experience one of three faults can screw up the  starting system - and I've had all three. I caution you be wary if the same symptoms present themselves- its not always the same cause!

OK scenario 1- you operate the key and get a loud buzzing or rattling sound.  This is probably a weak battery- the battery has enough power to operate the solenoid maybe even the lights alone, but when the solenoid activates, it connects the battery directly to the starter. The starter draws a huge current and so promptly soaks up everything the battery has to give, its voltage collapses and the solenoid disengages. This lets the battery voltage recover and so the process repeats- fairly rapidly and the obvious buzzing results. If this is your problem then a pair of jump leads should sort it immediately. 

A poor battery may simply be an old battery but if the fault recurs and you find yourself going through batteries like chocolates, check the rectifier/regulator- Mine was overcharging and cooking the batteries so even a replacement didn't fix it for long.

Scenario 2 you operate the starter, there's a loud clunk but the starter doesn't turn. Jump leads don't help.  For this you have two potential causes.

Cause 1- the solenoid has failed and isn't connecting to the starter. As the starter isn't getting power, its obviously not turning. You might find that if you turn your headlights on, then the bulb doesn't dim appreciably as you push the start button. It should virtually flicker out if the starter is taking power. You can test the solenoid by shorting across the two solenoid terminals with a screwdriver or equivalent The terminals I mean are on top of the solenoid under a rubber flap and have chunky, thick wires going to them. There is a reason for that, they are intended to handle a whacking current so be prepared for a flash when you short the terminals- and for whatever you are using to get really hot! However this bypasses the solenoid, so if that's your problem the starter should now turn. Incidentally this test works regardless of the position of the ignition key, but if you want to start the bike this way obviously you will need to have it turned on.

Cause 2 the starter is taking power, but its not turning. There are a few explanations for this but the most likely is that its either shorting out internally or something is physically jammed- either in the starter motor or the bike engine. Both explanations would mean that the starter will soak up large amounts of current to no effect. The headlight will dim whilst trying to start as all the current is sucked into the starter. You may notice the chunky leads described above that go from the solenoid are getting really hot so don't hold "start" down for too long. Obviously shorting the solenoid or using jump leads can't help in this case.

If you are "lucky" then maybe its just that you've left the bike in gear (duuuh!), or maybe the starter clutch or it's drive chain is jammed somehow. Check the gears and if that doesn't work try to loosen whatever is jammed by putting the bike into top and rocking it forwards and backwards on the wheels to shake everything up a bit. Put it back into neutral and try again. That might free the jam and let the motor turn... But its a short term fix. You will need to investigate further. Of course, if that doesn't help then you probably have a jammed or shorted starter motor and there's no alternative but to take it out and fix or replace it.

Well I've had all three of these and considering I do a restrained mileage I think that's not really very fair. Certainly its not the sort of legendary reliability we've come to expect from Japan.

The first time I had the problem it was a poor battery. It happened soon after I'd acquired the bike and I just thought the PO had probably never replaced the battery. However, when I found I was running through batteries like chocolate bars I realised it was more serious. I had a duff regulator rectifier that was overcharging and brewing up the batteries like teapots. Swapping that fixed the problem for a couple of years. I then had a duff solenoid- again changing that cured the problem, and now in its third incarnation; I have a stuck or otherwise buggered starter motor. No choice now, got to remove it, strip it and see if I can fix it! This is my experience of doing just that!

Removing the starter motor

Before we start, a warning; access to the starter is fiddly-  so chant your favourite mantra before you begin. If you want an easier life then remove the fuel tank, carbs and any engine bars fitted as well as the saddle. I managed without removing the tank or carbs and I left my Renntec engine bars in place- although I did have to remove the front bolt and lever the bars open to release the alternator cover!

You have to remove the alternator cover (left hand side) and its held on by 9 fastenings. 8 of these are 8mm bolts and one is an Allen cap screw. All of the bolts are the same length except two which are longer. The longer bolts go on the lower front of the case.

The Allen screw foxed me for a bit- it looks like an oil level screw, but alternators don't usually run in oil so I wasn't expecting any in the case. Well this one does! Be prepared and get a drain tray.
My camera battery failed during this strip and many of the pics I took didn't save but essentially removing the cover is like this....

Drain oil
Remove the alternator cover screws
Remove the 4 bolts holding the chain sprocket cover to give room to move the alternator cover
Tap the cover with a soft mallet or use a wooden bar to tap the front lower section where there is an accessible lug.

The cover is stuck on firmly with gasket goo and retained by the alternator magnets as well so it can be tricky to remove.
If you have engine bars remove the front mounting nut and loosen any others you can get to on the left of the bike. Lever the bar away from the motor so that you can fineagle to cover over the alternator and off the crankcase. It will remain attached by some electrical  leads passing through a rubber block. This should just push out of the cover, but again its a very firm fit.
You should now see two cross head screws that hold on the starter chain tensioner. Photograph the tensioner in position as its tricky to see how it goes back- these are some of my lost photos so I'm a bit stymied there! Hope I can figure out how to refit it. Anyway remove these 2 screws. I recommend an impact driver as they are in quite tight and their heads are made of cheese. They will strip easily rather than come out.

Chain guide is made of 2 parts and held by 2 screws. 

Remove the two sections of the tensioner and you will have enough slack to slip the starter chain off the starter sprocket at the top.
Next remove the thick wire terminal attatched at the top of the starter (10mm flanged brass nut).
Move to the right hand side of the bike and remove the two 10mm bolts that hold the starter attached to the crankcase. You will need a 10mm socket on a short wobble bar extension. Note that the battery/motor earth cable attaches at the rearmost bolt as well. Don't forget to reconnect this when rebuilding.

Now you have the pure joy of trying to remove the starter from its home when all exit routes are smaller than the starter in at least one dimension. It is necessary to push the starter backwards (ie out of the lhs case) whilst lifting it as far as possible to let it slide back. Once its out of the case you then have to try twisting and shimmying it in all possible orientations until it comes out. There is one- and as far as I know only one route by which the starter can come out, I found it by (considerable) trial and error and I can't remember what it was- sorry I can't be more help. I despair of refitting the motor!

Anyway, all being good you will end up with this.... I tried to rotate the motor by hand but couldn't. I took this to mean that it was siezed but I think it might simply be down to the internal gearing*.
* In fact after the rebuild I can turn the started by hand but it does take quite a bit of effort. In any event I also connected the battery straight across the motor (positive to terminal, negative to case) and achieved only a bright flash- no indication that the motor had any intention of turning so I was satisfied that the motor really is the cause of my problems this time around.

In the picture below the motor is positioned as it would be seen from the front of the bike and left or right in what follows refers to thsi view. The mounting points are on the left and the gearing/drive section (which rotates the motor) is on the right. The motor consists of a central section containing permanent magnets through which the motor armature passes. The armature doesn't extend right across the motor;  as shown here its lh end is supported by an oilite bush in the lh endcap (which also contains the brushgear and motor mounting lugs). It s right hand end passes through a second bush fixed in an internal plate and not visible until the case is opened. The end of the armature projects beyond this plate to engage with the internal gearing system which in turn transmits drive to the final drive shaft contained with its own bearing in the second endcap (on the right as shown below). The drive is then transmitted to the drive chain (and thus the motor) by means of a sprocket on the end of the final drive shaft. There are O rings between both endcaps and the body  section and also on the final drive shaft to seal its entry into the motor crankcase.

Starter as removed and illustrated as seen from the front of the bike, note the two holes for securing bolts in the lhs end cap and the solenoid connection terminal. The other end cap contains the final drive which projects into the motor crankcase cover. Note O rings between each end cap and the centre and around the final drive boss. Note that the body has a series of indentations- larger quare indentations at the drive end and smaller circular markings at the brush end. Note hor the lug on the rhs lines up with one of these larger squarer indentations.

I ordered a rebuild kit from WEMOTO

Starter rebuild kit from WEMOTO no SMU9115. Good value as most people sell simply the brushplate alone for over £50. This whole kit, including the brushplate and bearings and seals was around £30. Word of warning though- although specified for a 2002 bike the bearings didn't fit.

Stripping the motor

Remove the two long bolts that hold the unit together (8mm )

Removing the through bolts

The rhs end cap will then detach revealing the internal planetary gearing

Internal gearing system contained in the end of the centre section of the motor and above the internal plate supporting the armature: Ring and planetary gears are meshed with splines on the end of the armature (centre). The RH end cap is visible beside the motor body. 

The planetary gears have internal oilite bushes (not included in the rebuild kit). They don't usually wear. Note that the ring gear has a small indentation which matches a socket in the body. This contains a small (3mm) pin that prevents the ring gear from spinning when the motor operates

Anti-rotation pin in groove, Thick grease surrounding the gears. Note splined end of armature in centre.

Turning to the lhs end cap, remove the 2 brass terminal nuts and the stack of insulation washers beneath.

Solenoid terminal. Note O ring between end cap and motor body

Both terminal nuts and three insulation washers, the widest goes immediately below the bottom terminal nut.

You can then pull off the lhs end cap- In my case this was full of ground carbon and desperately in need of a clean. This reveals the commutator which was also greasy and dirty. Note that there are 3 shimming washers on the armature (not shown here) so don't loose these.

Lhs end cap removed, brushgear visible inside along with much carbon dust. Commutator now revealed. Note O ring on the central section

Press the terminal inwards and you can pop the brush plate out as the stud goes in.

Easing out the brush plate

This was also pretty dirty but the brushes were still present. These are cited as having a minimum service  length of  8.5mm for ER models. Mine were 11.5 mm and only a mm or two below new. I decided therefore to refit the same brushes once everything is cleaned up.

Brush plate as removed

But both end cap and brush plate cleaned up well. Note the oilite bush in the centre of the cap in which the armature rotates.

RHS end cap cleaned up with oilite bush in centre.

Returning to the body of the motor, the armature assembly also just slides out- it is retained by magnets in the body so there will be a resistance when removing it. In my case the armature was smudged with a greasy mush of ground up carbon brushes, but it cleaned up well with contact cleaner spray.

Armature as released. The copper commutator contacts the brushes in the rhs end cap and the splined gear at the other end drives the planetary gear mechanism to rotate the motor's final drive shaft

Returning to the case, the ring gear and planetary gears just pull out- watch for the anti-rotation pin and keep it safe. Clean all the hardened old grease off the gears and from the end plate beneath. I wasn't sure whether this had originally been graphited grease or if it has simply picked up carbon from the brushes in service.

Removing the ring gear, planetaries are off already.

Once the gears are out and the grease cleaned off, the end plate just lifts out. Note that this has a wide flanged oilite bushing in the centre, the flat side of the plate faces towards the gearing system, the projecting side (with the flanged face of the bush) faces inside the motor. This bush doesn't come in the kit. Luckily I didn't need to replace it but if you do its a 16mm id, 20mm od, 8.5 mm deep bush flanged to 23mm on the outside. I couldn't find a supplier.

Cover plate below ring gear after cleaning. Note central oilite bush in which the armature rotates. This is the flat side of the cover plate and faces towards the gearing, the recessed side faces inwards to accept the shaft of the armature.

There are three spacer/thrust washers that fit over the armature immediately below the flanged bush. Again keep these safe and remember to refit them!

Armature shaft- the three spacer or thrust washers are shown. Don't loose these.

From the foregoing it should be clear that the motor section of the starter doesn't drive the engine directly. This is because it turns too fast; rotation speed is lowered (and torque increased) by the gearing system. This passes the drive to the final drive shaft shaft via the two pins which hold the  the planetary gears. The end shaft is a press fit in the rhs motor end cap. Shown here before cleaning but after the O ring has been removed.

Starter final drive shaft seen from inside the lhs end cap. The two pins which are rotated by the planetary gears are visible. The impressions left by the ring gear (which cannot spin) are clear, the impressions left by the planetaries are smoothed out by rotation.

RHS endcap seen from above- ie as fitted into the crankcase. The toothed final drive faces upwards and the bearing can be seen surrounding it. The circlip that prevents the drive shaft moving backwards has been removed

The final drive shaft is a press fit within its bearing, and the bearing itself is a press fit within the end cap. Both are secured with additional clips. The first step is to remove the shaft from the bearing, so use circlip pliers to remove the circlip on the outside of the motor on the final drive shaft. Use a press or a vise, in combination with appropriate spacers to support the end cap whilst the final drive shaft is pressed out. Here I used a bench press and a supporting cup from a Draper press and pull system.

RHS end cap supported on a steel cup whilst the splined end of the final drive shaft is pressed downwards

Press in action

This releases the final drive shaft, now that this has come out the oil seal below can be seen. This keeps the grease around the planetary gears inside.

Final drive shaft removed (top left) and the rhs end cap (centre). The final shaft has a disc at its base on which the planetary gears are mounted. This disc also covers the oil seal and bearing. The oil seal is obvious once the drive shaft is removed.

The oil seal can be popped out with a screwdriver to reveal the bearing and its retaining clip beneath.

Oil seal popped out. Note the bearing in the centre retained by a wire clip.

The clip levers out with a screwdriver BUT cover the thing with a cloth as you do so because it will spring out with force and speed; its easily lost.

Clip removed, note open side of bearing was positioned towards the oil seal... from where no oil was ever going to come!

The bearing was a surprise to me. This is a single shielded bearing. Personally I can't see the point for ever using these, but in this case doubly so as I think its been fitted the wrong way round! Obviously a bearing will need to get its lubrication somehow. In this case the open face is intended to be exposed to the inside of the lhs engine case where oil is being constantly flung about by the alternator and thus able to penetrate the bearing. If that is true then this bearing has been fitted the wrong way round and its open face is oriented towards the oil seal whose very function is to contain the grease around the gears and stop it from reaching the bearing. Consequently I am surprised that this bearing is in as good a condition as I found it. It did sound a little ragged but certainly not enough to account for the motor failure I had observed. I note that the bearing provided with the rebuild kit is doubly shielded and this seems a much more satisfactory arrangement. Anyway before I can swap it, I need to remove it and so here I'm pressing the bearing itself out using the same support cup under the end cap but a socket above to press only on the outer edge of the bearing.

Pressing out the bearing

Bearing safely removed.

Success, bearing out.

This completes the disassembly of the motor, I have to say that I'm disappointed. I didn't really find anything that could have accounted for the failure to start. Certainly the bearing was in wrongly and did run a little rough, but this is no explanation. The best I can suggest is that the smudged excessive carbon deposited across the armature was shorting out the internal segments or jamming the armature's rotation. I was encouraged that others have apparently found that often a clean is all thats necessary. Anyway I cleaned everything thoroughly, and just to be sure that I hadn't got a dud armature I checked the electrical conductivities as suggested in the Haynes manual. These showed
1. Continuity between all commutator segments and all other commutator segments.
2. No continuity between commutator segments and armature shaft or metal plate stack.
3. Positive post brush connected to positive post and no continuity with brush base plate.
4. Negative brush in good contact with brush base plate.

I found that all commutator segments were indeed connected to all other commutator segments with a resistance of app. 0.3ohm between side by side or opposite segments. Given this, maybe all I needed was to clean it up? In any event its worth changing the final drive bearing, although the oilite bushes look fine. I just soaked them in engine oil for 48rs in an optimistic attempt to recharge their oil content.

 I cleaned everything prior to rebuilding, but here I got my first shock. The kit supplied (SMU9115) was clearly wrong. The bearing included was obviously too small. This motor requires a 6003Z bearing which is relatively easily obtained. As I still wanted to use the rest of the kit and needed to order an oil seal anyway (surprisingly not included even though you can't change the bearing without changing the  oil seal) I went ahead and ordered both to supplement the kit. These are 17, 35, 10 double shielded bearing 6003 and 20, 35, 7 nitrile  oilseal with garter spring.

Old and new bearing. That removed from my starter is at the top, the smaller bearing included in the kit is below.

Rebuilding the starter motor

Firstly clean the commutator with scotchbrite pad- don't use emery as the grit will stay in the workings and gradually wear things away.

Commutator cleaned

Before reassembly check out the orientation marks on the starter, there are striations on both end caps and the body to aid in reassembly.

Orientation marks on mounting end cap, linear moldings and small semicircular indentations

Orientation marks on gear end cap, striations and larger squarer indentations

I started by inserting the original brushes into their end cap, note that the contact stud has a rubber shield

Feed  the stud through the cap making sure that it seats correctly so that the rubber bushing surrounds the contact. This is all that stops your motor shorting out directly to the case. I would have expected something a little more positive like a nylon top-hat washer or equivalent, this does seem a flimsy feature for such an important function.

Insulation collar pushed up into cap and surrounding the stud.

Checking the new brush plate showed that there should also be a rubber O ring above this collar on the outside. It was missing when I took mine apart but there's a new one in the kit.

New brush plate showing the order of assembly of the various washers. Note the extra O ring .

... so I reinstated it.

Rubber O ring added above collar on the positive stud.

I attached the insulating washers and brass nuts to hold the stud in place. The order is; rubber O ring, two small insulation washers, large insulation washer, metal washer, two flanged nuts. At this stage (and without the armature) its a good idea to check that the positive stud really is insulated from the case so I checked and found no continuity.

The motor body is sealed by 2 O rings, in the original Kawasaki system these are different thicknesses, but in the kit they are identical and both are 1.9/1.7 sq section O rings. I fitted a ring to the brush cap, inserted the armature and then fitted the body section, noting the alignment. Check that the smaller thrust washers/shims are in place on the armature shaft before fitting it into the endcap; you need to lift the armature up towards the brushes as you insert it so that they are pushed back into their housings and can slip over the commutator.

Brush cap back in place

You can then add the three larger diameter shim/thrust washers over the collar at the other end of the armature...

Adding the three thrust washers or shims.

... and follow that this with the internal plate and oilite bush. Note the orientation pip that must fit into the cutout

Internal support plate with bush added, note orientation pip at 1 O'clock.

I could then turn my attention to the gearing end cap and I pressed in the new bearing being careful to press only on the outside rim. Once home, I added the internal retaining clip to hold it.

Bearing and clip in place. ote that this bearing is double sealed and doesn't need lubrication

The oilseal is then added and I pressed it flush with the housing using a seal press. Run some grease around the lip of the seal.

You can then press the drive shaft into the bearing supporting it with a suitable steel tube bearing on the inner race only. This is a bit awkward. You can use a deep socket as long as its not too chamfered on the inside. You need to press it in only as far as is necessary to expose the circlip groove so keep checking as you go or the shaft will nip up too tightly to turn easily. You can feed the circlip down the shaft...

... and clip it home in the groove.

Turning the end cap over I inserted the counter-rotation pin in its cut out (appx 10 O' clock in the picture below) and dropped in the planetary gears.

The ring gear can then be orientated and slipped home over the pin, meshing with the internal gears.

Not shown here, the next step is to add grease to the gearing (I used a couple of teaspoons-worth of Castrol LM), add the O ring to the body and refit the gearing end cap. Note hold the cap with gears-facing upwards and feed the motor body with O ring downwards onto it, or the gears and pin will all drop out in a greasy mess! Rotate the cap to align the orientation marks and mesh the armature gear as you fit it. Then refit the two long retaining bolts and put a new O ring in the drive shaft end groove.

Bolts refitted, new O ring

With great trepidation I tried connecting the motor. It didn't exactly burst into life, I suspect because the brushes weren't properly seated but after  an abortive twitch or two  it span smoothly and reproducibly. I'll go ahead and refit it to the bike, hoping that this has cured the problem.