Running without IAC

I have in the past been having issues with the idle air valves not working properly, bought a few secondhand adn cleaned them same sort of problem. Bought replacement stepper unit, this is still work in progress but intially couldn't get the stepper to stay in the body.

So generally I have been using the bike with the IAC air intake blocked and the air bleeds closed; probably for about a year now and 12,000 miles. Done the usual servicing and throttle balancing

Throttle balance at tickover is alway balanced

Now the question is - I am thinking of disconnecting the air hoses between the throttle body and stepper and putting on rubber blanking plugs, which may mean I need to set up tickover balance. Am I right in thinking that the idle air screws use the stepper motor air path?

As a note the stepper wiil always remain in place and connected so no nasty ecu errors.

I see nobody answered this one....not sure I know exactly where the air bleeds bypass the flap but always thought it was within each body (even if it joins the stepper air input before going to the inlet).

Also I once fitted (and abandoned) having stepper inlet block valve to resolve surging idle....despite many mainly 4V based claims, the engine just stalled if I shut the valve hot or cold (I could have tried adding extra bypass air at the TBs but never did that experiment.

So if you have a fully balanced and perfect running bike with no bleed air, no stepper air & maybe a 'between inlets balance pipe'; I'm guessing there's enough air passing the flaps to maintain idle - not sure that's right though !..... If blocking the 'joining pipe' throws it out of balance; you could just see if air bleeds get it back OR just leave a balance pipe in place (you're keeping the stepper anyway !)

Hopefully that'll stir the hornets nest

BrianD, not sure I completely understand what your problem is...
All I know is that stepper idle valve doesn't give any issues, usually, and when it does it's usually not its fault, something else is the problem.
I would check if the "sacred screw" is been messed up and if there's any air infiltration between the cylinder head and throttle body. There's a large o'ring there

paulbrice wrote:

Also I once fitted (and abandoned) having stepper inlet block valve to resolve surging idle.

Exactly what I have on my three 1200 Sports. The stepper motor is necessary for idle when the motor is cold, but holds the idle too high once it warms up. A manual pneumatic switch solves this problem, eliminating the influence of the stepper after a few km after startup. The sacred screw is not touched.

A nice bonus is the increased engine braking when the stepper is blocked. Worth doing it for this reason alone!

I would like to say that on my bike that the tickover has generally been fine, though when very cold around 3 deg C you need to keep the revs up a little for a short while before idling. in this warm weather pretty much no issue to worry about.

The stepper motor when fitted only seems to help maintain an ide speed [when cold ?] and works in conjunction with the ECU on startup, when it goes faulty you end up losing engine braking and the bike feels as though it is running away at junctions - not a nice feeling.

Think that I may well try blanking plugs and see how that pans out and as mentioned the engine braking is good.