2nd Gen Brutale B4 (990R, 1090RR) 2010+ Charging Stator Removal

481 Views 15 Replies 5 Participants Last post by falcn, 23 h ago

falcn

Discussion Starter · 20 d ago (Edited)

4

There don't seem to be any write-ups on this online, though it may be covered in the manual.

Even though the Shop Manual and MV call it an alternator, the charging system on the 2nd gen B4 bikes is not like the 1st gen where there is an actual varying field alternator. The setup in the 2nd gen is the common rotor/stator charging system found on many bikes these days. The three-phase stator can be accessed with the engine in the bike.

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The steps are very simple:

1. Remove the tank.
2. Disconnect and remove the voltage regulator/rectifier for easier access to the rotor cover bolts. 8mm wrench.
3. Disconnect the ground wire at the top rear of the stator (alternator) cover. 12mm socket. This gives easier access to the cover bolts as well.
4. Disconnect the starter cable at the end of the starter. Pull back the dust boot. 8mm wrench. Be wary, the nut on the back is not captive. Also 8mm. I use a magnetic pickup to grab it. Put a shop towel in the recess where the water hose comes from the water pump to save you having to fish for dropped bolts and nuts.
5. Use an 8mm socket with a universal and long extension and remove the 7 bolts around the cover. Place a shop towel at the bottom to catch the oil that will leak out. It is a small amount.
Take off the cover, wipe it out. The gasket is a metal based one. Make sure you have located the 2 dowel pins for the cover. I leave mine on the engine side.

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You should see the rotor.

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6. Use a holder (I have a pin clutch holder tool that fits the plain holes in the rotor. MV sells a special ($$) rotor holder tool. There are two smaller holes that are threaded for M7x1.0 bolts that are used by the MV holder. You can get a couple of your own and fashion a holding tool.
Hold the rotor with your holding tool. Use a 19mm 6-point socket and a breaker bar to remove the bolt. It is left hand threaded so righty-loosy!
There is a concave washer under the nut, don't lose it.
7. Remove the rotor. My hands were strong enough to just pull the rotor off straight out. The magnets are strong to be careful not to pinch fingers. You can use the two 7mm bolts to grab for more leverage. I just used the outside of the rotor itself after cleaning oil off.

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falcn

Discussion Starter · #2 · 20 d ago (Edited)

4

Part 2.
Remember the rotor is HIGHLY MAGNETIC. DO NOT DROP IT. DO NOT SET IT ON THE GROUND. Keep it away from metal shavings and other metallic steel objects that it will pick up.

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You have now accessed the stator. Prior to this I hope you tested the dynamic output and the resistance readings between the 3 legs. You should have 0.2 Ohms between any two of the three wires. More means the insulation between the wires has broken down and now you're measuring the combined resistance of multiple wires (I think).

8. Use a 4mm allen-key socket and remove the three (3) bolts holding the stator. It's a good idea to clean the oil off of them to prevent tool slippage and rounding of the head.
9. Use a 5mm allen-key socket and remove the holding plate that holds the wire bundle at the edge of the housing. There are two bolts.

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10. Remove the stator from the housing.

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Install is basically the reverse of the above.

I will come back and add the bolt torques from the shop manual.

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falcn

Discussion Starter · #3 · 20 d ago (Edited)

Part 3.

Torques
Wire guide bolts - 10Nm with a medium strength thread-locking compound

Stator bolts - Assemble the stator and tighten the 3 fastening
screws to 6-to-8 Nm with a medium strength thread-
locking compound.

Rotor bolt - Insert the rotor and the locking tool cod.8000B4304, assemble the washer and the nut and tighten to a torque of 65 Nm with strong thread-locking compound.

Cover bolts - reassemble the cover, tightening the bolts to 10 Nm. No special order is given.

I'm not so sure about the high strength thread locker on the rotor bolt. There was no evidence upon removal of high strength thread lock. Heck, none of the bolts seemed to have the indicated thread lock on the threads. I will use my medium on all.

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SlipperClutch

· #4 · 20 d ago

Great write up with pics - thanks for sharing!

I'm assuming your stator assembly failed, hence the need to remove?

(Just hope I don't need to refer to this for my bike anytime soon 😅)

mv2envy

· #5 · 19 d ago

Did you find any burn marks on any of the windings?

falcn

Discussion Starter · #6 · 19 d ago

2

SlipperClutch said:
Great write up with pics - thanks for sharing! I'm assuming your stator assembly failed, hence the need to remove?

(Just hope I don't need to refer to this for my bike anytime soon 😅)

Yep. I didn't even think that MV would use the ol crappy spade connector there. It was tucked down behind the hose from the pump out of sight.

I suggest you replace the stator spade connector that goes to the regulator/rectifier with a good connecter like a Deutsch DT 3-pin which is sealed and rated at 2x the amperage of the original.

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SlipperClutch

· #7 · 19 d ago

Sound advice...! I'm gonna have a crack at chasing this wire/plug the next time I lift my tank given my 1090RR is the same vintage as yours - preventative maintenance advice like this is always welcome. Cheers!

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falcn

Discussion Starter · #8 · 19 d ago

mv2envy said:
Did you find any burn marks on any of the windings?

Not as bad as yours, but def dark spots. The resistance test makes me think it's shorting on one pair when loaded, like just on the edge of being ok.

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falcn

Discussion Starter · #9 · 8 d ago

New stator is finally in the USA. In LA at customs...

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mv2envy

· #10 · 7 d ago

falcn said:
New stator is finally in the USA. In LA at customs...

Yup! The wait times can be painfully slow! Once it hits customs you still have 4 days time to receive it unfortunately. They aren’t fast about shipping times. That’s for sure.

falcn

Discussion Starter · #11 · 2 d ago

Got it yesterday!

falcn

Discussion Starter · #12 · 1 d ago

Damn - wasted time tonight putting it together. Should have loaded my track bike amd prepped for the track weekend instead.

New stator is $50 for a reason - the cable grommet was not in the right place to allow for me to align the stator to the bolt holes on the stator mount. Had to trim the outer wire guard and slide the grommet on the wires until I got it lined up correctly to allow it to bolt to the engine and the wire retainer to hold the wire and the grommet fit. Just buy the Ricks or OEM folks.

It WORKS - as in I have 35VAC on all pin pairs at idle.

However - I must have parasitic short to ground that is drawing power as the voltage at the battery charge input is only 12V. I bypassed the original wiring from the regulator to the charging input at the starter solenoid - I suspect the original charging wire may have melted another wire somewhere in the loom and is shorting enough to draw down power?

Not sure if I can check the output of the regulator (which is a new unit) by unplugging the starter solenoid connector after the bike is running....hmm.

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revhead1957

· #13 · 1 d ago

Check the 5pin plug on the regulator for loose connections. I had to replace mine, after checking the female parts individually using a male pin.
How old is your battery? All testing of charge circuits must be done with a known healthy battery.

falcn

Discussion Starter · #14 · 1 d ago (Edited)

revhead1957 said:
Check the 5pin plug on the regulator for loose connections. I had to replace mine, after checking the female parts individually using a male pin.
How old is your battery? All testing of charge circuits must be done with a known healthy battery.

The connector is new and the wires to/from it are new. New ground wire that runs to the engine ground strap that comes right from the battery negative. The positive wire I ran a new wire straight to the new starter solenoid relay connector.

But good point, I will double check my pins.

esq'z me

· #15 · 1 d ago

Good AC from stator and no charge voltage (14vdc) to battery indicates regulator.
I know … new.
Check wiring continuity and insulation.
all good? New reg/rec is no good.

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falcn

Discussion Starter · #16 · 23 h ago (Edited)

esq'z me said:
Good AC from stator and no charge voltage (14vdc) to battery indicates regulator.
I know … new.
Check wiring continuity and insulation.
all good? New reg/rec is no good.

Yeah, thought about that, gonna throw the old one in there to test and see if it's the same behavior.
The wires from the regulator are new to the starter solenoid connector and to the ground.

I'd have done that last night, but getting the dam wire grommet in the right place and swapping the wire clamp on the stator made the stator install take much longer than it should.

I've got a 2-day track weekend this weekend so this work will be paused until next week, which bugs me in the back of my mind. 🥴

I don't think I did, but maybe I wired the rectifier output to the wrong side of the starter solenoid connector...

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