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Old 12-19-2011, 10:27 AM   #143
Beastly Adventurer
JoelWisman's Avatar
Joined: Apr 2009
Location: STL, MO, USA
Oddometer: 1,392
Cowboy, by "cheap ass digital thermo" Do you mean something you have to press against the cover? Or one of the infra red jobs that you just point at it?

If you used something that you have to place in contact with the cover to measure it, you used something far more accurate then the infra red units even if it was a toy :)

If those measurements were made with a direct contact thermometer then I'm convinced you are onto something!

I fully agree that the stator temperature is the most likely culprit.

What I am having a hard time guessing is how much the cover temperature is affecting the temperature of the magnet wire.

Only a lot of time or some serious measurements is going to tell.

I'm a little leery about heat taping the header near the engine. At higher throttles as well as anytime the bike is running lean, the first foot of the header sees flame on the inside. Pushing hard I've hotter the first foot of my header glowing red many times.

Insulating it may cause it to fail and could also increase the head temperature when the bike is pushed and especially when it's hot out.

I don't see any issue with insulating the exhaust where it passes under the stator cover nor insulating the side of the cover.

Fins on the outward facing portion of the cover would help as would using a thermally conductive substance to bond the stator to the cover.

The part that is complex is the magnet wire is a major source of heat itself. Copper is very thermally conductive but it can still have localized hotspots. It only takes one tiny bit of the magnet wire overheating to cause a short that immediately overheats the rest of the phase and even adjacent phases.

Since a failure anywhere in the magnet wire will cause a failure everywhere, and since the stator produces a tun of heat by itself, it could be that these stators are shorting where they face inward at the furthest place from the cover, perhaps somewhere they are getting little or no oil splash. Or perhaps they are failing in the closest place to the cover and heat conducted by the exhaust is the major contributor.

I simply don't know, but anything that lowers the cover temperature sure as hell can't hurt and absolutely should help!

If I still owned one of these bikes or still worked for a BMW dealer I'd be buying some digital candy thermometers, pulling them apart and measuring temperatures at a few places on the stator.

Sadly I don't so all I can do is empathize from afar and enjoy the fact that both my current bikes are known for long life stators :)

Good luck. I think you guys are on the right path and are bound to find it before BMW issues a fix, if they ever do.

P.S. Cowboy, some of your posts are showing you to have anything but a "pee-brain", but riding 100 miles in Minnesota during winter for a burger is insane :p
Owned to date. Honda Aero 50, Honda Elite 80, Honda Elite 250x2, Suzuki Katana, Suzuki RF600, Yamaha YZF1000R, Kymco Xciting 500, Suzuki GS500, Suzuki Burgman 650, BMW F800GSx2, BMW S1000RR, Aprilia Scarabeo 200, Aprilia Caponord, Aprilia Sportcity 250
I love and miss you Jeneca and I'm sorry.
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