[Dez]

At hot and moist days (30C 60%) my idle usually starts very low (700 rpm) and very rough.
It settles at about 1250 after about 10 minutes of ride and behaves normaly.

What can it be?
No air leaks found, doesn't happen at good weather days.

Gt 2014, PCV, semi free flow exhaust

Tnx

[Arschloch]

I think there is not much you can do to keep the idle steady at all conditions unless it was throttle by wire as its the case in cars and the modern premium bikes.

[Bilgemaster]

Has it recently changed its behavior somehow? I'd been led to understand that most UCEs are just naturally a bit cold-blooded and prone to low revs and even stalling until they warm up comfortably.

My Iron Belly has a super-handy idle adjustment screw that can be easily tweaked from the saddle to suit all conditions, though it rarely needs it. Still, it likes a little light warming up before setting off in earnest too. From cold I'll just start her, get on my gear (about 2 minutes), run it very gently around a sort of three road half-circular cul de sac of maybe a few hundred yards behind my house, and then properly set off. She seems quite happy with this limbering up routine.

[Taurim]

The "starter" command on the left is here to accelerate the idle rev when the engine is cold. By the way it is not a choke like on a carb but only a bigger idle air intake and the ECU does its job to keep the air/fuel mix correct.
You should use it if the "starter" command cable is still there.

[hpwaco]

Bi starter lever on my 14gt never really worked due to excessive play in non adjustable cable.   One of these days I'll get around to installing the Hitchcocks adjustable cable that Tim of Western Cycle Supply was kind enough to get for me.  As received from dealer (REFTW) when it did start idle would jump to 1500rpm.  Thanks to forum adjustment was easy/simple.

[Arschloch]

Has it recently changed its behavior somehow? I'd been led to understand that most UCEs are just naturally a bit cold-blooded and prone to low revs and even stalling until they warm up comfortably.

My Iron Belly has a super-handy idle adjustment screw that can be easily tweaked from the saddle to suit all conditions, though it rarely needs it. Still, it likes a little light warming up before setting off in earnest too. From cold I'll just start her, get on my gear (about 2 minutes), run it very gently around a sort of three road half-circular cul de sac of maybe a few hundred yards behind my house, and then properly set off. She seems quite happy with this limbering up routine.

This is what's missing on the GT. 

[Dez]

No change in behavior, that is the last touch up needed.
I just like my stable rpm to keep below 1200.
I am working on a jig or some mechanism to delete the spring action so i can control it.
Not enough hands to ride and keep it open for a few minutes..

[GSS]

The only way to definitively fix this in my case was by adding a PC5 and increasing the fuel at startup. An easier thing is to adjust the large/flat brass screw at the top of the throttle body by 1/8-1/4 turn and that will adjust your idle speed and possibly improve startup. The two bolts at the rear of the tank need to be removed and the rear of the tank lifted up slightly to access the brass screw with a flat screwdriver.

DO NOT touch the little screw that looks like an “idle adjuster” at the right side of the throttle body….look up SinghG5 videos to see how to adjust TPS voltage as that can improve things as well.

A few rare folks had their ECU reflashed by dealers in some rare cases. Thanks.

[moschmi]

"DO NOT touch the little screw that looks like an “idle adjuster” at the right side of the throttle body…."

WHY?

[gizzo]

"DO NOT touch the little screw that looks like an “idle adjuster” at the right side of the throttle body…."

WHY?

Because it's preset at the factory to let the throttle close perfectly. It's not an idle adjuster.

Fool around with it if you want though, it's your bike.

[Taurim]

The idle air is adjusted with the screw on top of the TB. There is a special passage in the body of the TB for that.

The Butterfly  valve must be entirely shut at idle (but not too far away or it will stuck !). The screw is there for that.
Then the TPS position is adjusted so the volt reading sent to the ECU is correct. So don't touch this unless you have a way to check the voltage and keep the same value by moving the TPS after having moved the screw.

With a PC V it's possible to perfectly adjust the voltage for closed an WOT so I can touch it 
But I DO NOT use it to adjust idle !

[KD5ITM]

Iv owned my 2014 GT 535 since new.  It’s cold start idle has always been between 900 and 1,000 RPM’s regardless if the temp is 40F or 100F.  After about 8 - 10 minutes when the engine has warmed up, the is around 1,200 RPM’s. 

The choke lever on the left handle bar will raise the RPM’s 100 - 200 RPM’s. Technically its not a choke in the since like you would use on a carb, but it functions in the same way by helping the cold idle. I always pull the choke lever right after starting the bike on a cold engine start for about 10 - 12 seconds.  This helps the engine from wanting to stall while the cold idle RPM’s are trying to smooth out. When the engine is hot, no need to use it.

When my GT had 500 miles on it, I did its 3rd oil change and also installed the Power Commander 5 along with the Hitchcocks stainless steel free flow exhaust header and silencer and K&N free flow air filter.  The PC-5 made a world of difference with making the bike easier to start, idle much smoother and eliminating cold idle engine stalling as well as engine stalling when starting to take off from a stop sign or light.  The PC-5 comes with pre loaded fuel and timing maps that you can manually adjust when tuning the engine.  The PC-5 software also allows you to properly adjust the Throttle Position Sensor (TPS).  A lot of these bikes came from the factory with the EFI set quite lean on fuel which is not good at all for an engine to run lean.  They also came from the factory with the TPS not adjusted properly.  The PC-5 pre loaded fuel and timing map and properly adjusting the TPS makes a world of difference with the performance of the 535.

Another thing to check, a lot of these bikes came with the fuel line under the tank that goes to the EFI, a lot of times these bikes came from the factory with that fuel line having a kink or pinch point in the fuel line which restricts fuel flow to the EFI.  May not be your issue but good idea to lift the tank and check.  My bike had no issues with the fuel line.

Another good idea, if your bike still has the stock factory spark plug, toss that and go with the NGK plug.  Much better quality plug compared to the factory plug.

[SteveThackery]

As others have said, the low-cost EFI system has no automatic control of the idle speed, hence giving you the fast idle lever on the left handlebar.

Am I right in thinking the handbook tells you to hold it operated for 90 seconds after a cold start? As if anyone would do that!

I intended to conjure up some kind of locking mechanism for the lever, so I could get on with riding the bike while it warmed up, but never got round to it before I sold it. Perhaps someone could invent a way of doing that.

[Beeza]

Perhaps a hole could be drilled into the housing for a locking peg on a string? Fussy, but five seconds instead of ninety. A Cribbage sort of solution.

[KD5ITM]

Am I right in thinking the handbook tells you to hold it operated for 90 seconds after a cold start? As if anyone would do that!

I always hold in the lever when cold starting.  Not for 90 seconds.  Usually only for about 10 - 20 seconds depending on how cool the outside air temp is.

A few times while ridding with the RPM’s around 3,500, Iv pulled in that lever just to see what the bike does.  My bike doesn’t seem to like it very much.  The cruising RPM gets a little rough.  Doesn’t act like its going to stall or anything like that.  I can just tell that the bike is unhappy.   I wouldn’t want to ride around all day with the bi starter lever pulled in all the time.