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F800ST stator/voltage regulator replacement and oil

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4K views 13 replies 9 participants last post by  rodzghost 
#1 ·
I know its probably been done to death on the forum, but I couldn't find the answers with a search and I'd appreciate a couple answers;

I'm in the process of changing a burnt stator (voltage regulator while I'm at it) on my 2008 F800ST. A decent amount of oil came out of the engine stator cover, which I assume is normal?

Am I correct in saying the oil inside the stator assembly is normal engine oil? I just had a car mechanic tell me it was gearbox oil which doesn't seem right.

Thanks for any input
 
#3 ·
Engine oil. Lubricates and helps cool the engine, clutch, stator, gears.....

There are only four fluids - brake fluid, coolant, suspension fluid and engine oil. And gas.[:)]

The mechanic may want to stick to diagnosing things with four wheels. Or not offer unfounded advice.
 
#5 ·
Welcome, Jacquelartin. Why don't you fill out your profile and let us know what motorcycle you ride and where you live. That would help us answer any questions you may have.
 
#6 ·
I thought blinker fluid comes out when the stator cover is removed! [:D]

'cause, you know, the stator drives the blinkers, right?

But seriously, it is easier to make stator windings run in motor oil than it is to seal a chamber to keep oil and water out. Plus the motor oil can help keep the stator from getting extremely hot in a sealed compartment. Motor oil is hot but not as hot as wires can get.
 
#7 ·
As mentioned above, the oil is there to cool the stator. There were lots of early model stator failures due to the rotor design that didn't let much oil through. The newer design (2010ish) looks more like Swiss cheese which aids in cooling and prolongs stator life. I replaced my stator 4 times on my 08' ST before finally upgrading to the new rotor. It's been great since then.

Sent from my SAMSUNG-SM-G891A using Tapatalk
 
#8 ·
As mentioned above, the oil is there to cool the stator. There were lots of early model stator failures due to the rotor design that didn't let much oil through. The newer design (2010ish) looks more like Swiss cheese which aids in cooling and prolongs stator life. I replaced my stator 4 times on my 08' ST before finally upgrading to the new rotor. It's been great since then.

Sent from my SAMSUNG-SM-G891A using Tapatalk
More like 2013ish.

Sent from my SM-T813 using Tapatalk
 
#11 ·
It's a bit of a pain, but I have found that heat and a good impact wrench make it manageable. The rotor is heavy so it takes a while to get it up to 350 degrees f. You'll need a powerful torch (not a flashlight!). Once it's hot, hit it with an impact wrench. Don't try to lock the engine in TDC and use a big cheater bar like the shop manual says. The impact wrench is much more effective. Be prepared to catch a very hot rotor when it breaks free. Oh yeah, you will need a puller like this: https://smile.amazon.com/dp/B002308...abc_H4DE5RMHEBSP0W5KCBRT?_encoding=UTF8&psc=1

The biggest challenge is finding a new one to install. BMW only sells them as a kit with a stator. You will need special thread locker for the installation.

Sent from my SAMSUNG-SM-G891A using Tapatalk
 
#14 ·
Update: turned out I had a burnt out stator. New one is in and I get a steady 14.3—14.4 V, even at idle. Hardest part was getting out the screws I stripped that were holding in the metal tab for the wires. Note to self: get a pozi drive bit for the next time.

Reg/rec tested fine, but might upgrade that to a mosfet one. One thing that did concern me a little is that the epoxy was broken in a few places on my new electrosport stator. Seems to be running fine as is, but I might go back in and seal those spots up.

Lastly, once I had the old battery off, the tender was able to get it to 14.5v before dropping down into trickle mode. Pretty sure it's still toast though from all the times I saw it dip down below 10 v while running.
 
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