Stalling At High Altitude

[mamono]

Just wanted to run this by the forum in case maybe I'm missing a bigger issue than what might be happening.

Rode up to Lake Tahoe from SoCal, we booked it up the US-395 averaging 80-90MPH. Parked, ate lunch, walked around for a bit. Bike sat for 3 hours after the 9 hour hot ride up. We gear up and start heading out. Bike keeps stalling out on low throttle input while feathering the clutch since I was at a standstill. I shut the bike off, walk it over to the side, then try to start it again. Bike starts to idle ok, I give it a little throttle and it stalls out. I start it up again and immediately give it a lot of throttle this time maintaining over 3k RPM, bike starts to warm up and engine runs. After the warm up, engine ran fine.

Thoughts on what's wrong!

[Mohawk]

Do you have any mods ? Pwercommander etc ? If you use O2 eliminators, then in the idle to mid throttle the normal O2 sensor function is lost, so the engine will be overly rich at Lake tahoe, which is at 6,225 feet or 1,897m. If engine is standard then it should self adjust at these altitudes.

Mine was having trouble maintianing idle at 8,100ft last year up an Alp, due to being over rich at idle, it would start & like yours if you kept the revs up, then it ran fine.

[Cogswell]

The 5th and 6th gen FI systems (don't know about later gens) do not have an idle air control system (hence the manual idle adjustment screw) the way a typical car would. At high altitude the pressure drops so less air is admitted. I always notice my idle speed dropping when I ride through the mountains then returning to normal dropping back down. At the Pikes Peak summit it would barely run at all without throttle input. Without sufficient air there's probably some residual fuel left that needs to be burned off - that happens when you open the throttle and rev it up like you did to about 3,000 rpm. Once it's back to a normal AFR, then it runs fine. Shouldn't be anything to worry about.