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stepper motor

S

samann

Just got it firing!
Joined
Mar 4, 2009
Messages
24
On my '07 Griso, I bypassed the stepper motor and this thing runs and idles like an Italian V-twin is supposed too. No more pesky "run-on" and taking a few seconds to settle back down to a normal idle (even when warm)...I have yet to encounter any cold start up issues; so far it fires right up and settles into a nice idle right off the bat. Before, the bike almost acted like it had a vacuum leak the way it would slowly find its way back to normal idle.
Here's my question, other than idle, is there any other area the stepper motor would affect the engine? What are any side-effects to leaving it bypassed? The stepper is still plugged in electronically, I just plugged off the nipples on the side of the throttlebodies.

p.s I have a slip-on muffler and never experienced any popping on deceleration now or before the stepper bypass...

Thanks
Scott
 
samann wrote:
On my '07 Griso, I bypassed the stepper motor and this thing runs and idles like an Italian V-twin is supposed too.... Before, the bike almost acted like it had a vacuum leak the way it would slowly find its way back to normal idle.
Click to expand...
Scott, the vacuum leak was indeed "engineered" in. Only issue I have seen is that it doesn't like to ldle when cold, but if yours does, perfect. No downsides encountered yet on plugging it that way you have. Keep us posted as you go if anything turns up.

Also, do I have your info for the Modern Guzzi Registry? If yes, I don't think I have any photos... send to me direct; Todd at GuzziTech.com
 
I installed a valve in my stepper motor setup so I could turn it on when needed (cold motor) and turn it off when not needed.
 
GuzziMoto wrote:
I installed a valve in my stepper motor setup so I could turn it on when needed (cold motor) and turn it off when not needed.
Click to expand...
Please expand.
 
I have mentioned this before, but I do it again.
The stepper motor has two hoses running to thw two intake tracts and one hose running to the airbox. I cut the hose running to the airbox and installed a valve so that I could turn the stepper motor on and off. I used a fuel valve from some bike supply house, forget which one. By opening the valve the stepper motor can add air to the intake tracts allowing cold starts and whatnot. Closing the valve does not allow air to the stepper motor so that while it thinks it is doing what it does, it actually has no effect. I positioned the valve just below the point where it goes into the airbox and to the outside of the throttlebody (the original hose routing was inside the throttlebody, when I cut it and added the valve I ran it to the outside so it is easy to reach while riding).
I'm not really a picture guy but if you think it is a good idea I can see if my wife will take some pics.
 
I'd certainly like to see some pics of this as its a mod i'm thinking of doing myself!
 
Whichever way you do it...just do it!
I rode another 40 miles today and I tell ya' it is a different (happier) machine!
Scott
 
samann
Do you notice any imrovement in transmission clonking with upward changes from first to second and second to third as a result of bypassing the stepper motor?
Graham
 
I did. It could be my imagination, but the bike seems to shift better without the stepper motor.
I will try to get pics soon of the valve install. It is a $13 5/16" fuel line valve from Motion Pro.
 
My theory is that without the stepper motor bleeding air in the engine decels quicker when you shut the throttle. This results in better rpm matching when you shift.
I don't know if any of that is correct but I definetly felt cleaner, less clunky shifts without the stepper motor. Having the valve makes it easy to compare.
 
Makes it also easy to do a double-blind comparison: have someone who doesn't know the function of the valve switch it, and ride the bike without checking how the valve is set (and let a few others ride her too)

;)
 
Maybe I am just used to my Ducati and the way I shift it but I like the way the Guzzi behaves without the stepper function. I have never owned any engine (boat, motorcycle or car) that wound down slowly like my Griso did with the stepper. To me, the bike shifts better and is a lot more enjoyable to drive without the stepper...
Just my .02 cents...
 
I can relate to that, when you shut the throttle you want a nice clean and quick decellerate, not the slow rolldown you get with the stepper.
Or the sudden raise in revs when your sitting waiting at the lights! :unsure:
Its funny, all the money guzzi spent on technology, and us luddites are learning how to remove it! :laugh:
 
Surges in revs while idling that go away when you bypass the SM, and a quicker return to idle when closing the throttle when you bypass the SM (which is not supposed to do anything above idling AFAIK) ... that just means the functionality is badly implemented/controlled, no?

The only times I have a surge in idle revs is when I restart the engine after I stalled it. Then indeed it'll go to maybe 2krpm, and settle down pretty fast afterwards. Never had any real issues above and beyond that.
 
My bikes both have carbs, but I'm interested, might own one someday. Doe this stepper arrangement basically do the same thing as the idle air control valve on my car? Controls air flow in throttle bypass circuit. In addition to regulating idle speed, I suppose it might act to control deceleration for emissions purposes. Maybe that's why it would affect shifting?
 
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.
 
T Bill wrote:
Does this stepper arrangement basically do the same thing as the idle air control valve on my car? Controls air flow in throttle bypass circuit. In addition to regulating idle speed, I suppose it might act to control deceleration for emissions purposes. Maybe that's why it would affect shifting?
Click to expand...
Yes it does, and perhaps.
 
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