First off: Hello forum from California. I am, until recently, a happy daily commuter on a 2006 R1200RT with approximately 94k miles.
I bought the bike on consignment from a local BMW dealer about 2 years ago. The bike was serviced religiously by BMW prior to my purchase and has seen the same love me regularly (oil, valve adjustments, plugs, filters, etc.). About a year and a half ago, the bike went in to BMW for a new clutch and final drive bearings. Other than that, the bike has been pretty reliable and has run fine.
A few months back I started getting an inconsistent stalling issue that has only gotten worse. The bike starts fine, appears to idle fine at just over 1k rpm, and runs as expected at street and freeway speeds. However, when taking off from a stop, with a slow, normal application of the throttle, the engine rmp drops and the bike dies. This typically happens when rolling off from a stop, however, it has happened on the freeway a handful of times when the clutch was pulled in. The bike will fire back up right after and will keep going if I blip the throttle enough to get me rolling (from a stop).
This doesn't usually happen when the bike is first started (cold) as I can slow blip or roll the throttle without any noticed hesitation in the engine. It usually starts at my first stop, two lights after leaving my home, well before the bike has reached its operating temp. On the freeway, its pretty fluid and I hardly have to stop or come to a slow enough speed where this would be a factor. Once off the freeway, the issue occasionally resurfaces as I move through lights and stop signs. After several minutes of idling and playing, I have been able to replicate the flame out while at a standstill, bike in neutral or in gear.
Earlier this week, while riding home at freeway speeds, the bike began to surge. The bike was running at a mid-range RPM with just enough throttle input to keep it moving, not speeding up or slowing down. Add enough rpm to get the speed going again, or roll off the throttle a little more, and the surging stopped. As a result, I don't consider the bike reliable and have parked it until I can sort this out.
I've adjusted/checked the valves multiple times, did a throttle body sync using the TwinMax, replaced the O2 sensors, and have gone through the TPS reset procedure noted in the Haynes manual.
I'm pretty mechanically inclined, less so electronically, but I can chase down most issues I come across. I do not own, or know anyone who does, a GS911 tool at this time. Any help or experience in this manner would be greatly appreciated as the local BMW dealer quotes "investigative" mechanic work at $950 to start.
Sorry for the long, introductory post. I like to be thorough and give ya'll as much info as I can.
Many thanks in advance - Taylor