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stepper motor

RacerX wrote:
Brian UK wrote:
What this now needs is some automatic control which is activated by engine temp, much like an automatic choke.
Click to expand...
Yes. Think I found a solution... more here soon.
Click to expand...

Oh, I think another product will soon be available in the shop! :laugh:
 
Typically stepper motors and idle air control valves (basically the same thing) open up and let air in on decel to help emissions. This makes the engine slower to respond to a closed throttle and idle down. Some are worse then others. My Mazda is real bad whereas my Civic is hardly affected by it. I don't mind manually opening the valve for cold starts. I have owned many bikes with a manual choke so it's no big deal.
 
My V11 Sport had a cold-start lever which simply held the throttles slightly open. What a simple device it was - until you forgot about it, rode off and then wondered why the engine was racing at idle. Still I think it was preferable to a stepper motor although mine has not been a problem - yet.

Graham
 
Maybe the programming of the stepper motor in the ecu is better on the Breva 1100 as mine is perfect too. Reading the service book the stepper program responds to various inputs, one of which is engine temperature, so it should behave differently when engine is warm.
 
Well, I've certainly had the tickover stick at over 2k when the engine is hot on the Norge. Only infrequent, so maybe it's mechanical.

But have those who have disconnected the stepper motor still had that popping on overrun?
 
Mine had the popping and putting in a valve and shutting off the stepper motor all but eliminated the popping. If it still had the stock exhaust I would not be suprised if it completely eliminated it but I have a RacerX right side pipe. With that and the stepper motor off there is a percieved improvement in how the bike shifts and nearly all the popping has been eliminated.
For what it's worth I first removed the stepper motor by plugging the nipples on the throttlebodies but that was an issue with cold starts for me. I played with the screw your not supposed to touch in an effort to improve the cold start issue but in the end I decided I needed a way to turn the stepper motor on and off so I installed a manual valve.

StepperMotorManValve.jpg
 
RJVB wrote:
Are those the cylinder heads off a V11?
Click to expand...
I posted the pic for Moto above. Valve covers are for any V11, and made by a guy here in SoCal. Click below for more info;

 
GuzziMoto wrote:
Mine had the popping and putting in a valve and shutting off the stepper motor all but eliminated the popping. If it still had the stock exhaust I would not be suprised if it completely eliminated it but I have a RacerX right side pipe. With that and the stepper motor off there is a percieved improvement in how the bike shifts and nearly all the popping has been eliminated.
Click to expand...
Thanks, must work on that then.
What I now need to find is a small electric valve, and a thermostatic switch.
 
Its been a nice day today so got out the spanners and did the tappets.
while i was packing up i thought i'd try a little experiment.
Pulled the stepper motor inlet hose from the air box and plugged it with a bolt.
Started it up and oh my god!
Its running like a good old carb guzzi :woohoo:
Nice tickover, instant decelleration when you close the throttle, and when i took it out for a run, amazing!
Think i'll be fitting an inline valve, but until then, the bolt stays in!
 
GuzziMoto wrote:
Typically stepper motors and idle air control valves (basically the same thing) open up and let air in on decel to help emissions. This makes the engine slower to respond to a closed throttle and idle down. Some are worse then others. My Mazda is real bad whereas my Civic is hardly affected by it. I don't mind manually opening the valve for cold starts. I have owned many bikes with a manual choke so it's no big deal.
Click to expand...

Indeed. A very interesting solution.

Buells don't have a stepper motor but the Ecm is programmed with a slow-return-to-idle to reduce the chance of rear wheek lockup when changing down because no slipper clutch is fitted and the 1203cc V-twin is powering a 179kg bike. That feature does make for slow gearchanges though.

I'm coming around to the view that being able to bypass the stepper motor after initial warmup would be a good idea and could well make tuning more accurate too. As stock, the stepper motor must be causing some confusion while the idling vacuum balance is being perfected using the air bypass screws. Has anyone with the stepper motor disconnected or bypassed tuned their bike yet?

Graham
 
IIRC, there's a note by Guzzi disallowing that operation unless the "official" tuning equipment is being used. It seems likely that in that case, the stepper motor will be deactivated. OTOH ... if there's only 1 stepper motor that feeds both cylinders equally, it shouldn't affect the balance.
 
RJVB

Even with a well tuned engine the stepper motor causes slight RPM changes constantly. Watching the RPM readout on screen with VDSTS proves that. My feeling is that without the stepper motor the low speed fine tuning would be enhanced. What I'd love to hear is if anyone doing their own tuning has experienced that.

While GuzziMoto's mod looks very sensible an even better result would be achieved if isolators were placed as close to the throttle bodies as possible because there is still air in the tubes from airbox inlet to throttle body nipples which can be partially evacuated by the engine's sucking. At this stage I've no way of knowing if such a method is feasible. Think! Think!

Graham
 
Did I say it wouldn't? In fact, why would the idle RPM remain perfectly constant (or in other words, how big are the fluctuations of the RPM you observe on the VDSTS)?
 
I don't need VDSTS to be aware of the variations, I can hear them, and see the rev counter pointer moving 300 rpm or more.

Graham, the amount of residual air in the tubes is insignificant compared to the cylender capacity, so it would be removed in one revolution.
 
Brian

I can't detect the RPM changes on my rev countern nor hear any difference but watching the VDSTS screen definitely tells that the RPM is changing.

As I see it, the air in the tubes between airbox and throttle body is unlikely to be sucked out but there could be a partial vacuum setting up causing the air in the tubes to oscillate. A bit like the oil in my manometer! It probably doesn't matter in reality but when shooting for the ideal, aim for the bullseye.

Graham
 
Here's an idea. A Festo (or other brand) micro pneumatic control valve in the tube, hook it up to the headlight circuit and it will automatically close the stepper off from the fueling system when the RPM rises above the CPU threshold for lights on.

Edit: Just had another thought, to get around the air in the tube the valve could be hard mounted to the TBody.
 
The "fix" I will be prototyping/trying very soon, is to fit a simple electric solenoid air valve, wired to a waterproof mini toggle switch that will go the the bars (or mounted in the brake or clutch m/c covers on the Norge). The "kit" will have everything wired to length and ready to install for anyone interested.
 
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