Join Date: Feb 2006
Location: Indianapolis, IN
On stands, there's no load on the engine but friction and it'll easily go to the redline with the secondaries shut. But, it should also do the same with the secondaries wide open.
The difference here is going to be the air charge it can pull in. There is restriction with the secondaries closed and you're probably getting close to what the AFR should be. Open, and it's gulping in air and you probably are going super lean causing the engine to stumble.
It sounds like your STVA is working fine. Reconnect your cables and adjust it according to the manual.
Here's the rundown of how I would test:
1) Physically not delivering enough fuel. Test fuel pressure and volume delivery. TEST! Don't assume.
2) Unplug the electrical connections the IAT, AP, and IAP sensors. These three sensors are used to calculate the air density. Unplugging them will use stock values. If the bike suddenly runs right, start plugging them in one at a time, in that order. It'll code with the sensors unplugged, but you're testing for bad data.
3) Vacuum leak. A small leak in the IAP hose system will cause all kinds of goofiness. Ever have a hole in a soda straw? Same thing. Suck hard enough and you'll get some drink. Same situation here. With the secondaries closed, you're putting a lot of negative pressure on that leak. Basically, it's making the IAP have bad data and when you close the secondaries, you're altering the engine conditions to match it (possibly).
4) Vacuum leak. This is where we get into either unlucky or stupid. The idle air adjustment screws have o-rings to seal them up. If they've rotted and cracked, a leak can form. Your WD-40 test should work here. Or, they've all been backed out so far you've provided a secondary air source. Still, this wouldn't affect WOT to the redline. That's why I've put it last.