Decent Tune-up

[p6x]

4 hours ago, docc said:

The tolerance in the Workshop Manual is given in Degrees of Opening:  3.6º +/- 0.5º

If that percentage can be applied to the 157 mV value, the tolerance would be +/- 21.8 mV . . . That impresses me as really broad and undesirable.  With how fiddly the value is being affected by the tightening procedure, I am generally satisfied with 150-157 mV.

As you, I don't think the tolerance in degrees is directly applicable to the sensor mV reading.

If we had to work out an mV tolerance, we would have to map the full mV output along the opening. We are not even sure it is linear.

But if it was, we could take readings and graph the TPS mV per each degrees; if we get a straight line, then we could derive the tolerance in mV. I am guessing we would not be able to correlate it though. Even the 157mV may not be applicable for every TPS. They are bound to have a tolerance too.

[p6x]

The B part of the tune up requires this cable: https://www.lonelec.co.uk/index.php?route=product/product&path=57_20&product_id=51

However, it is useless without GuzziDiag program, and as stated on the site, it has been tested with High Sierra 10.13. I don't own a MS computer, and my MacBook Pro runs Catalina (10.15.5).

I have read that GuzziDiag does not run on Big Sur (11.5.2).

To find out if the program and the FTDI driver work on 10.15.5, I still need to purchase the kit with the interface.

[dbarb3]

what bit are the air bypass screws

[docc]

13 minutes ago, dbarb3 said:

what bit are the air bypass screws

Flat blade screwdriver, about a #2.

Visible in the upper right of this image "Air Bypass Screw" (green arrow):

[Lucky Phil]

On 8/30/2021 at 10:41 AM, p6x said:

As you, I don't think the tolerance in degrees is directly applicable to the sensor mV reading.

If we had to work out an mV tolerance, we would have to map the full mV output along the opening. We are not even sure it is linear.

But if it was, we could take readings and graph the TPS mV per each degrees; if we get a straight line, then we could derive the tolerance in mV. I am guessing we would not be able to correlate it though. Even the 157mV may not be applicable for every TPS. They are bound to have a tolerance too.

The TPS output is non linier on the V11. The linier version of the same TPS has fixed mounting screw ferrules without slots.

Ciao

[bentombed]

Hello  - my bike, 2002 scura, is idling really high - i checked the air bypass screws and the idle adjust,  the bypass screws were almost all the way in, the idle screw just about that way too. after opening up a turn on the bypass screws and starting to unwind the idle screw the bike started to idle faster?  i cannot find a way to slow the idle speed down, it was idling at around 1900, and now it sits at just on 2k. the right side idle screw is all but wound out. the is enough play in the cable and the choke is not on.  I'm not sure where to go from here?    I will read through the whole thread to see if anyone else has had this problem, but it cant hurt to ask

 

 

[Pressureangle]

9 hours ago, bentombed said:

Hello  - my bike, 2002 scura, is idling really high - i checked the air bypass screws and the idle adjust,  the bypass screws were almost all the way in, the idle screw just about that way too. after opening up a turn on the bypass screws and starting to unwind the idle screw the bike started to idle faster?  i cannot find a way to slow the idle speed down, it was idling at around 1900, and now it sits at just on 2k. the right side idle screw is all but wound out. the is enough play in the cable and the choke is not on.  I'm not sure where to go from here?    I will read through the whole thread to see if anyone else has had this problem, but it cant hurt to ask

 

 

Your engine can only idle high if it's getting enough air to support the RPM. If your idle screws are closed and your throttle blades are closed, you probably have a rubber boot leak, or your balance holes are open. Double check your 'choke' to see if it's holding the throttles open when in the 'off' position. My own has to be disassembled to allow the throttles to close completely. I can imagine a piece of debris behind the handlebar lever on mine, trigger style not rotated. 

[docc]

9 hours ago, bentombed said:

Hello  - my bike, 2002 scura, is idling really high - i checked the air bypass screws and the idle adjust,  the bypass screws were almost all the way in, the idle screw just about that way too. after opening up a turn on the bypass screws and starting to unwind the idle screw the bike started to idle faster?  i cannot find a way to slow the idle speed down, it was idling at around 1900, and now it sits at just on 2k. the right side idle screw is all but wound out. the is enough play in the cable and the choke is not on.  I'm not sure where to go from here?    I will read through the whole thread to see if anyone else has had this problem, but it cant hurt to ask

 

 

Realize there is also a right side idle screw that can hold the throttle linkage open. It is rather obscured (below in red) and difficult to turn. Perhaps a "ball head" hex key would be helpful. @Pressureangle's advice about an air leak is right on.

[bentombed]

11 hours ago, Pressureangle said:

Your engine can only idle high if it's getting enough air to support the RPM. If your idle screws are closed and your throttle blades are closed, you probably have a rubber boot leak, or your balance holes are open. Double check your 'choke' to see if it's holding the throttles open when in the 'off' position. My own has to be disassembled to allow the throttles to close completely. I can imagine a piece of debris behind the handlebar lever on mine, trigger style not rotated. 

i'm starting to think this is the case -  i will check the boots and balance holes and anywhere else air could be leaking from - thank you @Pressureangle

Cheers @docc i'll try find the right side screw as well. 

[bentombed]

11 hours ago, docc said:

Realize there is also a right side idle screw that can hold the throttle linkage open. It is rather obscured (below in red) and difficult to turn. Perhaps a "ball head" hex key would be helpful. @Pressureangle's advice about an air leak is right on.

@docc

you were bang on!  the right side was too far out and was preventing the throttle linkage from closing properly. adjusted that out, then i reset with the left side adjustment. sitting happily at around 1100 now.

you guys are awesome! thank you

Edited June 6, 2022 by bentombed
hyperlink

[gstallons]

When you do your Super-tune on this bike , you want to keep this idle kicker out of the equation . You will tighten it after everything else is done .

[bentombed]

48 minutes ago, gstallons said:

When you do your Super-tune on this bike , you want to keep this idle kicker out of the equation . You will tighten it after everything else is done .

The super tune is coming - i had to get it ridable first bike had sat for a long time prior to me owning it.  Cheers!

[Gmc28]

I’ve also been eye-balling my throttle linkages, poking around for causes for my idle stumble during the warm-up period in cold or warm weather.  Throttle linkage shouldn’t be the cause of that symptom, but just looking things over.  She purrs like a kitten and runs sweet when warmed up, but starts hard (catches, then stumbles and quits, and a quick throttle blip kills it), and then stumbles every 5-ish seconds during those first “4000 revolutions”.  Didn’t used to do that, and after a couple of tune-ups last couple of springs (post winter) she runs as good or better than ever except for that initial start period. 

I do now keep that right side idle adjust screw most of the way out.  I used to adjust it back in to where its just almost touching the fuel lever on the TB, but I’ve started just leaving it out.  Shouldnt’ make a difference, and makes it easier to do TB sync next time, but its a change.  My eyes must have been deceiving me, but the other day i was looking over the left side idle adjust, looking to adjust the idle just a smidge higher, and after turning the screw in a little, could have sworn i saw some daylight between the adjustment screw and the lever….. how could that be?  Looked around for linkage getting snagged somewhere (was idling just around 1000rpm), then finished double checking TB sync at idle and making just a slight adjustment on the air bypass screws, then looked again and the daylight i thought i had seen on that idle adjustment was gone.  Hmm.  Probably seeing things.  Or was something actually hung up that i cleared from messing around down there (?).  By that time, it was warmed up and idling and running fine, with the stumble gone.

To be clear, she’s well tuned in accordance with “decent tune-up”, and when warm is idling around 1150 (slightly high by choice), has the minor and typical stumble in the mid 3’s rpm, but otherwise runs/idles/rides sweet once warmed.  Just that hard starting and stumble, where even “idle lever” all the way up may barely keep it from quitting for the few couple minutes. 

Not sure I should bother with all my ramblings on this little issue of my persistent idle stumble during warm up, but maybe someone has some thoughts, and writing it down helps my brain sort through things, so here you go… some tedious reading material if you’re so inclined :->  cheers

 

[audiomick]

Just for the record:

After this post, there was a bit of discussion about the tolerance for the TPS Voltage.

On 8/29/2021 at 9:27 PM, p6x said:

Is 157 mV the "zero" setting of the Throttle Position Sensor? e.g. with no throttle input, fully rested, one should aim to obtain 157 mV on the multimeter.

...

What is the tolerance in mV? +/- 5 mV?

I don't recall seeing a tolerance figure in Volts in the replies.

Just recently, I read a figure in a workshop manual. I tried to find it just now, but couldn't. The stated value was 150 mV +/- 15 mV.

That puts Meinolf's preferred 157 mV well within the tolerance. Also, I watched Karsten and Beard at the annual rally of the German Forum setting up a V11. Karsten actually aimed for 160 mV, but settled on 157 mV as close enough, because that is where it landed after tightening up the TPS.

160 mV would also have been within the offical tolerance. I don't know why he was aiming for that, but I dare say he had a good reason.

[docc]

In the Workshop Manual, Section I/ Carburation Procedure (page 52 in my manual), the TPS setting is specified at 150mV (no range). The idle setting of the TPS is given in a range, but shown in Throttle Plate opening angle in degrees (3.2º - 3.6º).  [Please note the final idle rpm, idle TPS voltage, or idle throttle plate degrees are NOT critical, as long as the idle is not too low.]

What is critical: indexing the throttle plate opening to the map. This is the function of the TPS. On a V11 Sport/LeMans, this is set with an accurate voltmeter with the throttle plate completely closed.

More voltage is not better! @Meinolf determined the 157mV setting from his study of the actual lookup tables. IIRC, the steps in the lookup table are 7 mV. So, if a range could be derived: 153.5-160.5 (?)

Is close enough good enough? My experience has been that when the TPS indexing to the map is spot on, mySport runs magically, from idle stability to heat tolerance to the nefarious 2800 rpm *hiccup/stumble to the freight-train torque-pull into the upper reaches of the power band.