S2R800 Fast idle Lever

[He Man]

Im trying to delete the stepper motor on the TB of my S2R1000 and replace it with a fast idle lever. It appears the S2R800 has one that is connected to the throttle cam. Does anyone know if I can simply swap the cam and LH switch then plug the TBs?

[Howie]

I don't know if that would work.  Maybe a throttle lock as an alternative?

[stopintime]

Last time (10 yrs?) this was discussed I think the message was that the cams, and therefore whatever is inboard of it, isn't removeable. Probably, Duck Stew said that anything that has been assemblied can be taken apart. Maybe it's just the butterfly valves and their axle that are stuck, but have a good look on the throttle bodies first. Worst case you have to get parts from a 800. The bodies are the same size and measurements between 800 and 1000. Not sure about the 1100Evo.

Howie's suggestion is surely a lot easier

[ducpainter]

How about a throttle off an early SBK. It has a fast idle button.

[He Man]

How about a throttle off an early SBK. It has a fast idle button.

Was that like a choke on a carb or was it a lever rather than button?

I managed to find someone on advrider who (on a ktm 990 or something) did a bunch of mods to add an anchor point to his TB cam so he could basically crack it open upon start.

https://advrider.com/f/threads/stepper-motor-removal-with-idle-cable-installation.1185374/

I don't know if that would work.  Maybe a throttle lock as an alternative?

This was suggested too and I think its probably the most reasonable way to do it. What i dont quite understand is if the stepper is deleted, how the denser air during winter would impact idle. Does that mean I have to adjust the idle at the map level seasonally?

I forgot how bad my idle was before i stopped riding and my starter motor brushes were burnt out before i took it apart so I cant even unplug the stepper and turn the bike on right now to test in this balmy 25degree weather!

[ducpainter]

The early SBK's, S4's, and some ST's had a button on the throttle housing that you pushed. It raises the idle by the amount you adjust into the cable. To release it you just turned the grip forward.

[Orange16]

The fast idle button throttle was 748-916-996 only.  It tends to push off easily when you close the throttle, but it is by far the easiest way to achieve the desired outcome here.

The best throttle bodies with fast idle mechanism to bolt on would be M1000 or 1000SSie.  The M800/S2R800/800SSie throttle bodies should be the same physical part, except for the the base throttle opening angle - that will need to be adjusted to the correct angle for the 1000.  Although it's only approx 0.5 degrees difference at most I believe.

You will need to flash the ecu with an M1000 based file, otherwise the ecu will log fault codes if the stepper motor is disconnected/removed.  Also might run funny at low speeds due to the expected big vacuum leak not being present, I'm not sure on that bit.  I've not tried it.

Fit caps to the inlet manifold fittings.  Don't run a hose between the two manifolds - it makes them idle badly.  Or block the hose if you do.

Are you sure it has a stepper motor issue?  They very rarely play up in my experience, but get blamed for lots of problems.  Loose desmo closing clearances, dirty throttle bodies, poor idle set up can all make them idle badly.  Even with a functioning stepper motor.

[Howie]

The early SBK's, S4's, and some ST's had a button on the throttle housing that you pushed. It raises the idle by the amount you adjust into the cable. To release it you just turned the grip forward.

Yup, I remember that.

On the carbed bikes they used the word "choke" but it really wasn't a choke.  A choke makes the mixture by cutting off the air supply.  The Mikuni CVs added fuel.  My M1000 with the DP computer, on a cold day wanted some fast idle for about long enough to get my helmet on.

[He Man]

The fast idle button throttle was 748-916-996 only.  It tends to push off easily when you close the throttle, but it is by far the easiest way to achieve the desired outcome here.

The best throttle bodies with fast idle mechanism to bolt on would be M1000 or 1000SSie.  The M800/S2R800/800SSie throttle bodies should be the same physical part, except for the the base throttle opening angle - that will need to be adjusted to the correct angle for the 1000.  Although it's only approx 0.5 degrees difference at most I believe.

You will need to flash the ecu with an M1000 based file, otherwise the ecu will log fault codes if the stepper motor is disconnected/removed.  Also might run funny at low speeds due to the expected big vacuum leak not being present, I'm not sure on that bit.  I've not tried it.

Fit caps to the inlet manifold fittings.  Don't run a hose between the two manifolds - it makes them idle badly.  Or block the hose if you do.

Are you sure it has a stepper motor issue?  They very rarely play up in my experience, but get blamed for lots of problems.  Loose desmo closing clearances, dirty throttle bodies, poor idle set up can all make them idle badly.  Even with a functioning stepper motor.

Thanks for the detail info. Im not sure what the problem is to be honest. I do know that my stepper motor is suppose to be disabled as a result a of a previous flash and dyno tune. I really need to get the bike back together and fired up to see whats going on (starter motor went kaputz). If all the button does is crack open the throttle a little bit, then if I kept the existing 1000DS TBs, it would have idle issues at extreme ends of temps wouldnt it? Id expect the fast idle TBs to have an adjustment screw to manually set idle.

[Orange16]

Not sure I understand your reasoning.  Used for non stepper motor applications, the button is simply a fast idle device, like the lever.  The ecu takes care of fuel enrichment for both start up and engine temperature.  If it is tuned properly, it should idle just fine hot, and require the fast idle activation to keep it idling when cold.

The stepper motor allows air to bypass the throttle blades, so the ecu has a fuel table for stepper motor opening and rpm to take account of what is a controlled vacuum leak.  It is a fast idle by default, controlling the idle speed as set in the ecu mapping.  Many systems use a stepper motor to manipulate the idle stop itself, which in a management sense removes one table from the control mapping as you're no longer working out how to account for the controlled vacuum leak.  The ecu just opens the throttle to maintain the desired idle speed.  I'm not sure why Ducati use the bypass stepper style system.  Well, it would have to be cheaper / easier / more space efficient for Marelli to supply it.  The Conti ecu systems use the MAP sensor to manage the impact of the stepper motor.

The idle speed on the models without a stepper motor is set by the air bleed screws.  They are, just like the stepper motor, a bypass of the throttle blades.  An expected, and accounted for, vacuum leak.  You run the engine until it is hot, then wind the air bleeds out to achieve the desired idle speed, adjust the idle mixture to the desired setting, readjust the air bleeds if the idle speed changed (increased) and readjust (lean) the mixture accordingly, repeating until it's right.

The throttle stops are not meant to be adjusted.  On linear TPS models, adjusting the idle stops ruins the intended relationship between expected and actual throttle opening.  Not that that stops people doing it.

Not sure if any of that answers your question.

[He Man]

I should lead with

"My ECU has been modified and I was told that they deactivate my stepper motor, but its still physically installed and idles like dog shit when its cold".

As a result of the stepper motor being disabled I am looking to delete it entirely and go with a fast idle lever. Your response sheds a much light on how the system works so I can plan accordingly! Thank you very much!