idling adjustment

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g.m.c.janssen
Posts: 35
Joined: Mon Jun 01, 2009 6:33 am
model: 907 I.E.
year: 1993
Location: Leiden, The Netherlands

idling adjustment

Post by g.m.c.janssen »

Hi folks

my 907 just idles a bit to fast when at normal temp, at 1500-1750 rpm. Want to adjust it to 1250 rpm. How? found the following in the 907 shop manual. But they do not explain how to proceed for a good adjustment. Just fiddling around?
thanks George
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Ducati 907 i.e. 1992
Laverda 750SF 1972
Laverda 1000 3CE, 1974
Laddie
Posts: 56
Joined: Fri Sep 21, 2007 12:00 am
model: 907 I.E.
year: 1991
Location: Australia

Re: idling adjustment

Post by Laddie »

George,

the Bowden cable screws are like idle mix screws on a carburetor..they only let air in to the manifolds (one for each).
you could stuff around with them and the idle mix potentiometer on the ECU and get a reduced RPM result... but that might also be a flat spot between idle mix and open throttle (not desirable).

assuming the idle mix is correct now (and has been set with a CO meter) it's probably best to leave them alone.

the place to set the idle is at the main throttle cable connection; balance both butterflies (preferably with vacuum gauges) then set the idle screw. You should do the whole "tune and TPS set up"...but might be lucky and get the lower revs just with the screw adjust..
it's a shit of a job because you need to prop up the tank to do the screw adjusts and run the bike; maybe your fuel lines are long enough??

an anomaly I found was that my nicely balanced idle vacuum went 10 - 15% out-of-whack at 4000 RPM on open throttles...which is where I prefer to have the tune "right" ...grrr.. so my idle was re-set a little off balance - and I left it around 1200 - 1400 so it wasn't lumpy...
I suppose it's up to the individual where you want the bike running smooth and how much idling you do; mine gets mainly highway use so I don't care about lower revs too much.

Note: don't let the screw off too much so as to allow the butterflies close fully in the throttle bodies!! They will stick and make throttle control and acceleration jerky when they let go.
Laddie
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du907
Posts: 342
Joined: Fri Jul 08, 2005 12:00 am
model: 907 I.E.
year: 1992
Location: Winston-Salem, N.C. USA

Re: idling adjustment

Post by du907 »

Laddie is right. You can do the whole TPS adjust, then balance the throttle bodies, then the air screws, then the CPU screw if you have something to stick up the pipe and read the CO2.
However, to just adjust the idle "speed" the set screws are your best bet, . . . . however . . . . . there are two, one at each throttle body. The one on the right is not accessible unless you take the gas tank off, then the air box. Last time I had mine apart I drilled an access hole from inside the air box so that I could get to it ONLY after taking of the the tank and top of the air box.
The thing to do is get on the left side of the bike on your knees. Look from the front just beneath the radiator and look for the throttle linkage that the choke cable and throttle cable connect to. You will see the left side throttle body idle set screw that you can adjust with a long screw driver or a 6 or 7 mm socket on a long extension. This will open both throttle body butterflies to set your idle. Adjusting the one set screw just means the other non-accessible set screw doesn't touch the stop on that side any more.
Good luck.
du907
Tamburinifan
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Re: idling adjustment

Post by Tamburinifan »

The thing to do is get on the left side of the bike on your knees. Look from the front just beneath the radiator and look for the throttle linkage that the choke cable and throttle cable connect to. You will see the left side throttle body idle set screw that you can adjust with a long screw driver or a 6 or 7 mm socket on a long extension. This will open both throttle body butterflies to set your idle.
+1.
And, first, do make sure you have a little freeplay in throttle cable
so it always sets at the same RPM at idle.
Gert

907 I.E. -91
M900 -97
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g.m.c.janssen
Posts: 35
Joined: Mon Jun 01, 2009 6:33 am
model: 907 I.E.
year: 1993
Location: Leiden, The Netherlands

Re: idling adjustment

Post by g.m.c.janssen »

Thanks du907, that makes life simpler. Will try it in comming days. But still wonder what the function is of the 2 "by-pass" screws in the picture?
Ducati 907 i.e. 1992
Laverda 750SF 1972
Laverda 1000 3CE, 1974
g.m.c.janssen
Posts: 35
Joined: Mon Jun 01, 2009 6:33 am
model: 907 I.E.
year: 1993
Location: Leiden, The Netherlands

Re: idling adjustment

Post by g.m.c.janssen »

Hi Du907,

Went on my knees in front of my Duc. What an experience!

But could only see the cylinder head of the horizontal cylinder. No cables or throttle screw whatsoever. Have to remove any fairing?
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Ducati 907 i.e. 1992
Laverda 750SF 1972
Laverda 1000 3CE, 1974
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du907
Posts: 342
Joined: Fri Jul 08, 2005 12:00 am
model: 907 I.E.
year: 1992
Location: Winston-Salem, N.C. USA

Re: idling adjustment

Post by du907 »

g.m.c.janssen

You are going to have to bend over a little more! Probably lay on your back and look up to see the screw. Check out the enclosed photo with the red arrow pointing to the screw. Sorry, best picture I could get. You can do it. I use a small rachet with extension, then a u-joint adapter, then the socket.
Good luck

Image
Mc tool
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Re: idling adjustment

Post by Mc tool »

Dunno if this is applicable to the 907 as I,ve never seen one up close but , For poxy to get at screws on carbs ect I have cut the socket bit off a suitable sized cap screw and soldered/ welded it to the head of the afore mentioned poxy screw ( carb ballancing screw on the SS ) and then use a very long ( home modified ) ball end allen key, this way I can approch from an angle and the ball end is a lot easier to keep in the socket, especially with a magnetic tip . Paint the screw head dayglo or white. If you tune your own bike these wee tools will save you a lot more time than it takes to make them :)
I wish I was young again............Id be heaps smarter than last time
g.m.c.janssen
Posts: 35
Joined: Mon Jun 01, 2009 6:33 am
model: 907 I.E.
year: 1993
Location: Leiden, The Netherlands

Re: idling adjustment

Post by g.m.c.janssen »

du907 wrote:g.m.c.janssen

You are going to have to bend over a little more! Probably lay on your back and look up to see the screw. Check out the enclosed photo with the red arrow pointing to the screw. Sorry, best picture I could get. You can do it. I use a small rachet with extension, then a u-joint adapter, then the socket.
Good luck

Image
Thanks a lot, found the screw, Will try the adjustment in the comming days
Ducati 907 i.e. 1992
Laverda 750SF 1972
Laverda 1000 3CE, 1974
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Janky59
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Joined: Sun Aug 28, 2022 6:56 pm
model: 907 I.E.
year: 1992
Location: Salisbury, MD USA

Re: idling adjustment

Post by Janky59 »

Opposite of what the OP had going on, my idle speed is a smige low to my liking, at 900-1000 rpm. It will occasionally stall, or just seems on the verge of it constantly. So I want to bump it up a hundred or two rpm.
So reading this post I thought I would give this adjustment screw a try. First was to locate the screw mentioned above, the picture was of some help. But left a lot to the imagination.
Here’s a better pic for others to reference.
AD9CB2C8-FA76-423B-BB96-D0EC46549522.jpeg
AD9CB2C8-FA76-423B-BB96-D0EC46549522.jpeg (140.81 KiB) Viewed 65 times
And I used this stubby straight bit driver: Or the 7 mm socket works too.
A8518379-BF0A-48E7-894C-2CE71FFA0653.jpeg
A8518379-BF0A-48E7-894C-2CE71FFA0653.jpeg (243.99 KiB) Viewed 65 times
So far the half turn I gave it hasn’t made much difference, but I ran out of daylight and it got too cold to make further adjustments and test rides.

I’ll report back after a full turn.
Current moto stable:
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‘18 BMW R1200RT
‘11 Ducati Hypermotard 1100 EVO
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Fvee3
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Joined: Wed Mar 02, 2022 9:27 pm
model: 907 I.E.
year: 1992
Location: New Jersey,USA

Re: idling adjustment

Post by Fvee3 »

That is a great shot of the adjuster.
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