Generator / Stator Issues (K5/6/7/8)

[gsxbarmy]

NOTE: This thread is also available to download as a PDF file from the Downloads (General) Section

If you hear a noise from the left side of the engine (typically the generator cover area), or your 14 stops charging the battery, a common problem on the later model 14's is the stator bolt having come loose.
To check this put your 14 on its main stand and so long as the ground is flat and level, you will only lose a little bit of oil - if at all from removing the generator cover
TIP:   When taking the bolts out of the generator cover, you will find that 2 of them have washers on; these bolts need to go back in the same position when you re-attach the generator cover. A simple way of doing this is to get a bit of cardboard, draw an outline of the generator cover and then push the bolts through the cardboard at the appropriate point as you remove them.
TIP:   Watch your fingers when removing the generator cover as the magnets will try to pull it back onto the crankcases. You also have to be careful that the starter idle gear does not come off its shaft (if at all possible). Recommended approach is to gently pull the casing away slightly and insert wooden wedges to hold it apart. Then get a small thin screwdriver and check that the starter idler gear (top right hand corner) isn't coming away with the casing. If it is, using the screwdriver gently push it back in place (if it does come out, don't worry, we'll cover that later!)
Take off the sprocket cover and unplug the wire to the alternator before removing the generator cover. Once removed, you can then check the stator bolt and tighten if required. This has quite a high torque on it at 118lb/ft and you will need to hold the generator rotor to do this. For the generator rotor, you will need a 31mm spanner which is not easy to find. If you cannot locate a 31mm spanner, then the cheapest way to make one is to get a calor gas spanner (which typically are cast and circa 30mm) and then using an angle grinder, just slightly widen the jaws (you may not need to do this as the calor gas spanners are generous in size often).
Before tightening the stator bolt, it's worth removing and cleaning / drying the taper that the stator sits on using some paper towel and brake cleaner or similar. A lack of oil on the taper will give a better 'grip' between the stator and the crank. Before refitting lightly smear some blue Loctite on the bolt.



Before remounting the generator cover, if the starter idler gear came away when you took the casing off, then this needs to be re-mounted first. Recommended method for this is to once again put your socket on the stator bolt and just gently apply pressure so the crank turns slightly backwards whilst remounting the idler gear - it only needs a touch and the starter idler gear will pop back on with no problems.
Once all is good, then you are ready to re-mount the generator cover as before watch your fingers as it goes on, the magnets in the generator will suddenly pull it onto the crankcase and you don't want your fingers in the way when it does!
Once the generator cover is remounted, then re-insert the bolts in the correct order (with the bolts with the washers on in the correct place, else you will get an oil leak) and torque the cover bolts up to 8.1lb/ft.



TIP:   Before fitting the sprocket cover, just check that you have re-attached the generator plug!
If the reason you undertook the above procedure was charging, and you found no problem with the stator bolt, then it's possible you have a problem with either the generator itself and/or the rectifier. The checking of these is covered elsewhere On the forum under the 'Electrics' section
Further reassembly instructions (if required) can be found on Page 3-63 of the workshop manual.

[gsxbarmy]

Update to the above. On some 14's after retightening the bolt, it has come loose a second time. Suspicion is that the bolt - being a high torque - stretches slightly. Replacing the bolt with a new one has resolved this,

So recommendation is that if you have this bolt out or need to re-tighten it - fit a new bolt at the earliest opportunity to avoid it (possibly) happening again.

[froudy]

If I could add something to this post Dave.

When you remove the generator cover for the fist time for whatever reason, remove the bolts that secure the stator to the cover. Clean them and apply threadlock before refitting. This will ensure that they do not come undone and chew the stator up. It's happened to a member on here recently and was also a common fault on the DRZ400.

[gsxbarmy]

Excellent point and a good addition Steve thank you! 

[Endless]

That was me it happened to; If I'd known earlier, I would have opened the stator case and put loctite on both the main stator bolt and 4 smaller bolts securing stator to the cover. Very quick and easy prevention. Should probably note that in my example, given the low km's, it is highly unlikely the stator has ever been touched since factory and has come loose from factory fitting .

[Irish in Oz]

In my opinion the bolt simply comes loose from the torque and quick engage of the starter roller dogs. If the bolt was left hand then there would be no problem but I am sure the Japanese engineers have a reason for it, which I think is that if anything in there comes loose the rotor will spin on crankshaft therefore the crankshaft does not lock up sending you sliding down the road.

[Buddynq]

I had this problem a while ago but fixed it without drama. It did come loose again recently but I didn't have a suitable torque wrench or adequate spanner to hold it from spinning when tightening.
I had the opportunity today with all the tools but when I torque the bolt up it puts pressure on the cog behind magnet, therefore doesn't spin.
I have currently got it to a certain tightness which allows it to start but nowhere near 160nm

An aircraft mechanic at work thought it may have a worn shaft

Any thoughts??

[gsxbarmy]

I had this problem a while ago but fixed it without drama. It did come loose again recently but I didn't have a suitable torque wrench or adequate spanner to hold it from spinning when tightening.
I had the opportunity today with all the tools but when I torque the bolt up it puts pressure on the cog behind magnet, therefore doesn't spin.
I have currently got it to a certain tightness which allows it to start but nowhere near 160nm

An aircraft mechanic at work thought it may have a worn shaft

Any thoughts??

Try replacing the bolt itself Buddy, as on a couple I did they came loose again. A new bolt with some loctite and all good.

I think it may be one of the type of bolts that stretch slightly when torqued up, so has to be replaced it time.

[Buddynq]

I'll give it a go Dave.
Just for my understanding - The cog behind the magnet obviously needs to be free spinning in a right hand direction (as you looked at it).
So a longer bolt (Stretched) torqued at 160nm will will prevent that cog from spinning at all?

[seth]

The cog as you describe it is the starter ring it needs to move in one direction as  that's how it works .( other wise when the bikes running the engine will be turning the starter motor.)
Mine was lose (it seams to be a problem on K5's more than other years).
I torqued it up with locktight and it's been ok since.

[gsxbarmy]

I'll give it a go Dave.
Just for my understanding - The cog behind the magnet obviously needs to be free spinning in a right hand direction (as you looked at it).
So a longer bolt (Stretched) torqued at 160nm will will prevent that cog from spinning at all?

Correct and as seth says Buddy. Sometimes just applying blue loctite can work. I tried it twice on mine and it held for a while but then came loose again. The new bolt sorted it, so I'm assuming it's one of the stretch type bolts (I got my replacement from a dealer, just to be sure I had the exact right bolt). It's a pretty close fit, so it's possible that even a slight stretch may stop it

[Woodsy]

Hi, I need to remove the generator ring but haven't got the removal tool (bolt) my question is dose any one no what the size and thread pitch the bolt is to remove the generator ring .
Cheers (WOODSY)