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I've been having a lot of problems with starting my bonnie this season. Had to jump start it 5 times already and it's never sat more then a week without running.

I started it up and checked the voltage to the battery, 12.5V (while idle) and up to 12.8V ish at 3k rpm slowly falling back down to 12.5V.

So I read this
http://www.triumphrat.net/speed-triple-forum/104504-charging-system-diagnostics-rectifier-regulator-upgrade.html

But I never got a clear answer as to the problem.
I checked the regulator and got no shorts from any of the phases to the battery terminals. I did get 0.5V in diode test mode when they were forward biased (again for all 3 phases).

The resistance between coils for the stater was below 1 ohm.
The resistance between the coils and the chassis was 1 Mohm. This is where I'm not sure, the article says there should be no reading, (open circuit or maximum resistance), 1 mega ohm is pretty darn high, but it's not an "open circuit".

last while the engine is running I get 18v at idle measured between the phases and 30v at 3k rpm. (I didn't rev it higher because it seemed like a good result and all the voltages were approximately the same between the three phases)

So now I have no idea what the problem is, the stator seems to be ok, and I'm not sure how to test the regulator beyond what is listed in the article.
After testing the bike I figured I'd bring the regulator to my local bike shop to see if they can test it better than my multimeter. After he told me they can't test Triumph stuff he said that if the bike doesn't die after it's started then the charging system is working.

The bike runs great after it's started so according to the tech the charging system works, but it outputs less then 13V and I can only get 2 or 3 seconds of cranking out of the battery before it dies.

Any ideas on what the problem could be would be great.
 

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If you're on the original regulator-rectifier, replace it now with a MOSFET upgrade which is available in a plug-and-play version. Put in a new battery while you're at it, unless you think the current one still has life, and you'll probably be good to go.

The OEM r/r is marginal and gets worse over time, and should be replaced anyway to prevent this kind of problem.
 
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