Carb mystery

[bill gise]

Guys:  I've got a problem.  I have 2004 GS 500F.  Bought the bike-not running.  Checked the Cam timing and found it to be out-results were two bent intake valves.  Replaced the valves, re-did the timing-installed new diaphrams in the carbs and jets--and gaskets.  NOW THE PROBLEM:   The bike will start on one hit of the starter and will sit in idle 1000 RPMS.   When blipping the throttle, tac goes to 3000 and slowly keeps climbing.  The butterfly in the carb is completely closed and the slides on the carb are completely down at the bottom.  Neither moves-and the RPMS keep increasing.   I've checked the boots for air leaks and checked everything on the carb but to no avail.  This carb is the new style with the little diaphrams on the top of the diaphram covers.  When you remove the vacuum line from the engine to the little diaphrams, the engine will drop RPMS and then stop.   It seems like there is an air leak or something is open.  An information will help---a little background-I've been fooling with bikes for about 50 years, so know some about bikes--didn't just fall off the pumpkin wagon.  Would appreciate anyone who has any information or ideas regarding this problem to either email or my phone number is 717-880-6244. 

[sxthunttokill]

Have you checked and adjusted the valve clearance on the intake and exhausts valves? I've found hanging idle issues to be valve clearance, vacuum leaks, or lean fuel

[The Buddha]

The thing could just be lean.
A tight valve will not let it idle, as soon as it starts cold, a tight valve will make it want to stall unless you blip the throttle.
A vacuum leak will cause it to rev to 3-4k as it warms but it usually will cause it to want to stall when cold. Or even be hard to start.
You likely are lean. Vacuum line to top of carbs controls the petcock. You disconnect it, and you shut off the fuel. Try disconnecting the vaccuum line but run it in prime. Check that.
Its lean - my guess.

Cool.
Buddha.

[W201028]

Far be it from me to question the buddha, but I think the diaphragms on top the covers bill is talking about are the valves that slow the rise of the slides during fast throttle openings. I believe it is part of the emissions setup to make the last of the gs bikes 50 state legal. When i was having trouble with my gs, I spent alot of time on these forums trying to learn the function of those extra valves and solenoids/sensors that adorn the new carbs.
From what i recall, there is a solenoid on the bottom of the right carb that upon ignition advance opens the diaphragms on top the covers, venting excess vacuum thus slowing the rise of the slides. This saves fuel and/or lowers emissions resulting from an unnecessary rich condition. I have plugged these valves and removed the solenoid from my bike, with no adverse affects that i can notice.
It could be these valves are leaking on your bike bill, but I dont know if that would cause an issue at idle; more likely only a lean condition when you open the throttle and the slides fail to rise. I think these valves are vacuum actuated from the solenoid, so even if the solenoid was stuck open, I cant see it causing a runaway rpm without extra input to the throttle. I wouldnt toss out the idea of a secondary air injection leak either, but I have not heard many problems with that system. The newer bikes do pose a few unique problems