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High idle speed - 1200 Sport

I just used a metal fuel valve of the right size to fit the line between the airbox and the stepper motor. I cut the line and installed it such that it is easily reachable while sitting on the motorcycle, almost like the old days of a reserve tap. Having something automated sounds cool, but I tend to lean towards the KISS principle.
 
Hi Brian. Just to be clear, the temperature switch you have fixed to the cylinder head intersects the power supply to the stepper motor ?
 
Hi Brian. Just to be clear, the temperature switch you have fixed to the cylinder head intersects the power supply to the stepper motor ?

I'm guessing it will be a pneumatic switch. Switching the electrical connection to the stepper motor will bring up the "SERVICE" triangle of death, unless it is disabled somehow.
 
At the top of this page I have a "Sticky" post about giving the stepper motor a little TLC. Easy once you have removed the airbox.
When you spray WD 40 onto the returnsprings and the idle drops, or you push on the throttle linkage, and it affects the idle, it could possibly be wear in the throttle shafts in the th. body. With a closed throttle the low pressure on the downstream side of the plate is quite low, and will invite unwanted air through a worn bushing/shaft raising the idle.
Open the throttle to free the plates in the bore, and try to wiggle the shafts to detect free-play.
Also your emission canister, if still in place, may have a failed hose somewhere that introduces unwanted air. If it is removed, there should be no more than a balance pipe between the fittings on the intake manifolds.
Is it a high mileage bike?
 
Sorry to bring up an old topic but have a fast idle issue that seems a bit different. 2008 1200S that idles around 1700rpm, bike has a stepper motor shut off valve fitted that use to make a difference but now has no effect. Tested valve and it is still shutting off. Having trouble balancing throttle bodies at idle with Carb Tune as after setting high speed balance idle balance is always out again. Motor also speeds up and hunts when setting idle. Found when it is idling fast you can shut down motor then on re-start idle is ok for a short time before climbing again. TPS has been reset.
 
Sorry to bring up an old topic but have a fast idle issue that seems a bit different. 2008 1200S that idles around 1700rpm, bike has a stepper motor shut off valve fitted that use to make a difference but now has no effect. Tested valve and it is still shutting off. Having trouble balancing throttle bodies at idle with Carb Tune as after setting high speed balance idle balance is always out again. Motor also speeds up and hunts when setting idle. Found when it is idling fast you can shut down motor then on re-start idle is ok for a short time before climbing again. TPS has been reset.
Time to look for an air leak. The bike is old enough to have one from rubber deterioration. Check all rubber lines feeding the throttle bodies and look carefully at the intake boots and related. A WD-40 or Contact cleaner test while running can help as well.
 
Ok so all apart and all boots and hoses look fine. Tested solenold valve again. Tested ohms on stepper motor and got 51.4. Book says 50, guessing that's within limits. Bit lost now for a explanation.
 
Try putting some positive air pressure down the same hose that is connected to the stepper motor (after disconnecting it from the stepper motor). Not too much, just enough to chase the air leak with some water spray.
 
Thanks Dave. Just to confirm, solenoid valve in naturally closed with no power but is the Stepper motor is naturally open with key off ? Have pressure tested lines but all are fine.
 
Thanks Dave. Just to confirm, solenoid valve in naturally closed with no power but is the Stepper motor is naturally open with key off ? Have pressure tested lines but all are fine.

I doubt if the stepper motor is open with the key off. As far as I know, it's basically a small pump. But if you disconnected it to apply some pressure down the lines, then it won't matter.

Your post is a little cryptic for my understanding of English. Have you applied some pressure down the lines and looked for leaks?
 
Yes, I have inspected and applied pressure to all lines and all seem fine. But with the stepper motor removed should you be able to blow through the entry port and have air come out to two ports feeding the throttle bodies or should it be closed?
 
I really don't know, it might depend on whether any of the inlet valves are open. There might be a restriction similar to a carb jet to reduce the effect of the stepper motor.

Have you tried squeezing the hose with a pair of pliers as I suggested post 15 on the first page? This is the easiest way to determine whether the stepper motor and hose is contributing significantly to the idle speed. The idle speed should change, but the motor doesn't die.
 
The stepper motor is a variable valve controlled by ecu signals regarding engine temp. It never blocks the air off completely. It is also fully open with the ignition turned off. There is no restrictors downstream of the stepper. The air enters the TBs downstream of the throttle plates through non-restrictive ports.
There is a small piston coming out of the stepper motor entering a tapered orifice (all internal, and impossible to see). It moves in "steps", allowing the correct amount of air (or not!) to enter the intake, thereby varying the idle speed. With the engine fully warmed, the valve is in the "minimum air" position. It does not close fully, still supplying that small amount of idle air that in the previous F/I generation(s) was supplied by the "air bypass screws". It also replaces the manually controlled "fast idle cam" for cold starting.
Your engine should idle around 1200-1250 rpm. If you pinch off the air supply hose (reachable under the tank from the R/H side)(you are cutting off that "min. air"), it should drop by at least 200 rpm.
It's 3am, I'm up nursing a cold, hope this helps (back to bed)
 
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