The 5 second rule applies to both dropped food and fast idle knobs.

 

I usually pull the "choke" out to the first position (it's usually around 25 C or higher around here) to start. If the bike's totally cold, it'll rev at about 15-18 for a couple of seconds, then climb to 20. When it hits twenty, I push it in and take off.

There are several "my bonnie won't start" threads around here (including one of mine), and the solution is often that the rider isn't using the "choke". So now I always use mine to start my bike, regardless of how hot it is.

 

Thank you. Mine won't have a tach so I won't be able to use rpms as a benchmark.

 

I think the "choke" is more of an enricher, but since I haven't taken it apart or seen any exploded views of the inside of the throttle bodies, I'm not totally sure how it works. Not sure if it richens up the mixture by changing the electronic signal that the injectors get, or if it's like a carb-type choke and reduces the airflow (which would also make the mix richer).
When my motor is totally cold, I pull it out to the 1st stop, then push it back in just a bit (to prevent it from revving too high when cold), then start it up. It revs to about 1500-1800, I wait about 10 seconds, then push it in just a bit more so the revs drop to maybe 1200 or so. Then I ride off nice & easy, after about 1 minute of riding I push it in all the way.
It is kind of funny that with an EFI system like this you have to do any sort of manual adjustment at all.... With my Daytona 675 that I had just before this, it was totally automatic; whenever I started it, it would just idle at 1000 rpm, cold or hot. Maybe this is just a feature that Triumph thought would be more nostalgic to have on the twins?

 

The Bonnies "choke" is really a manual IACV (Idle air control valve). In more sophisticated EFI systems this valve is motorised and controlled by the ECU to provide a rock-steady idle and compensate for loads being applied and removed from the engine at idle, stuff like torque converters being engaged, air-con, window heaters, etc (in cars).

It consist only of a measured air leak through a passage that bypasses the throttle butterfly and its main purpose on the Bonnie is to provide an accurate amount of initial air for starting and a fast idle for warming up. No connection to the ECU.

You could do without it by operating the throttle with a certain finesse and precision, but that would take far too much explaining to riders and it's not that easy to provide the right amount of starting air with a heavily gloved or cold hand. The real choke is really the oil temperature sensor, it's that component that tells the ECU to enrich the mixture and also advance the ignition timing when it detects a cold engine.

It's also simple and cheap which pleases Triumph no end, but it's certainly not the only EFI bike with such a system.

64-post thread debating this issue here , there are 100's more, write something like "efi choke" on the Google Custom search window:

http://www.triumphrat.net/twins-talk/228701-if-the-bonnie-se-is-fuel-injected-why-manual-choke.html

 

I've owned bikes since the 60s and thankfully the EFI "choke" system on my '12 t100 seems to work perfectly when applied as the manual suggests...cold start second (full out) stop, not so cold first position, and the thing warms up fast after which I ride off with no choke and a happy engine (well...it SEEMS happy). Not sure why anybody does it differently, but then life is full of mysteries.

 

I have never once had the need to use it...like ever. In fact mine as it currently stands is broken off. My bike will start at 20f outside with no issues.

 

Likewise have never needed to use it, but its a great place to mount an 8-ball or whatever else takes your fancy.

 

I use mine on the 14 t100 as the manual suggest. I find when I don't, my initial take off is a little rough and doesn't want to get going. I start the bike up with the 'choke' knob in the correct position for the temp, throw on my gear, push it in and roll off to a smooth and warm engine.

So, from my experimentation my bike seems to like it, but I can't say as to whether I'm doing more harm than good.

 

Alrighty then ! I do understand a little bit about IAC on an EFI engine. My boat engines of 1998-1999 design vintage have that type of thing. Unfortunately the IAC sensors tend to be a bit cranky and there’s a little filter upstream in the air channel to the sensor which can become clogged when you least expect it.

Good to know that you’re not directly messing with the ECU on the Bonneville when pulling or pushing that “choke” knob. On a bike with no tach I expect it’ll just take some experience & listening to the engine to get to know conditions if/when to use it and how long.

 

Well this certainly is and old post, but since the OP started off with the same bike as mine I will add my two cents.
Just got mine ,a '2014 T-100 with very low miles. In my experience starting is a little rough if you don't use the "choke". If used as described in the manual then everything works like it should. Haven't had the bike in cold weather yet but I'm pretty sure I'll be using the choke

That's my story and I'm sticking to it 😉

 

Do u use it on every start i have been having battery issues and i feel this is reason why i have to press bstart swith h 2 tiimes sometimes

 

I use it every time, if I don't she has a hard time starting

 

Yes i read in manual now that it needs to be used every start one click above 77 degrees and all way out under 77 Its really not a choke its more of a idle advance some bikes have them hooked to computer and they do the adjustment themselves guess this was easier and less expensive for triumph

 

Yes, old thread, but I'd just like to add something for those who may be new to EFI. I know it's pretty common knowledge, but be sure to remember that no throttle is needed when starting.

I pull mine all the way out, it fires right up, then almost immediately push back in halfway, and then push it all the way in after a half minute or so and let it idle while I put on helmet & gloves. (and would likely leave it halfway a little longer in colder temps) Runs flawlessly when I take off.

 

Yes, old thread, but I'd just like to add something for those who may be new to EFI. I know it's pretty common knowledge, but be sure to remember that no throttle is needed when starting.

I pull mine all the way out, it fires right up, then almost immediately push back in halfway, and then push it all the way in after a half minute or so and let it idle while I put on helmet & gloves. (and would likely leave it halfway a little longer in colder temps) Runs flawlessly when I take off.

This is pretty much my procedure