CB1100 Idle speed instability problem

[max]

Enzo there are 4 calibrated gauges required together with the knowledge to deal with the interaction of the iacv positions.

From the question i think you may not have done a carb/ throttle body sync before, so before changing anything i would suggest to watch several yt video's to find out what's involved, how to do it and why.
Throttle sync is only required when the engine is warm and at idle, there is no other reason to adjust the sync adjustment which is why Honda does not supply service info, they want to avoid the risk of getting it wrong which is easy to do, the adjustment screws are not fixed like the old carburettors so by adjusting too much you can drift out of range and end up with a rich or lean mixture.
With carburetors you adjust the amount of fuel mixture, with a throttle body you only adjust the amount of air per cylinder, there is a difference.

For instance when i bought my cb919 the engine sounded like a harley at idle, the engine only ran on 2 cylinders, it took me a while to work out why, and after syncing the throttlebody with the 4 gauges it started to run like it should have; somebody mis-understood what they did and got it wrong.
Once i had the vacuum gauges installed and started the engine it was very apparent that the sync was off.
All four cylinders have the same capacity so they produce the same amount of vacuum at each intake stroke at the intake when the valves open, this amount can be measured with 4 individual vacuum gauges and adjusted so they read the SAME amount of vacuum supplied through the iacv and adjusted ( equalized ) by the 4 screws under the throttle body.

As soon as the throttle is opened slightly the butterfly valves and the tps start doing their job and the idle screws are no longer of any importance, they are only required when the butterfly valves are closed.

You can then verify this by using a piezo electric pressure sensor in the exhaust and watch the pulses it produces with each exhaust stroke which should be equally the SAME, you do need an automotive oscilloscope for this check so you can record and watch the pulse train.
Hope this helps.

My advice; if there is no problem don't introduce one.
With all respect for your ability and thanks for all your help, i appreciate it; cheers

Ciao Max, come puoi vedere non sono proprio un principiante



Ma questo era un motore a carburatori, sui corpi farfallati si sono un principiante.

Il mio CB1100 non ha problemi, ma vorrei sapere dove precisamente collegare i tubi del vacuometro perche ci sono diversi tubi sul corpo farfallato e non vorrei sbagliare.

Mi piacerebbe controllare se le leggere vibrazioni al manubrio e agli specchi, che ho a motore caldo e in folle, sono fisiologiche o è il minimo non perfettamente alliniato.

Translated; But this was a carburetor engine, on the throttle bodies I am a beginner.

My CB1100 has no problems, but I would like to know where precisely to connect the vacuum gauge tubes as there are several tubes on the throttle body and I would not go wrong.

I would like to check if the slight vibrations in the handlebars and mirrors, which I have when the engine is hot and in neutral, are physiological or if the minimum is not perfectly aligned.




here is what i use to check carbs/throttlebodies, i have adjusted the gauges so they read equal amounts of vacuum ( see the different needle positions ).
There are several adapters, the straight ones connect to cb500 carbs, the ones above them connect to the two inner connections of the throttle body and the other 2 hoses connect to the outer t.b. vacuum connectors.

The set of three hoses are connected to the same chambers but have to stay connected because they measure vacuum for the e.c.u. ( i think, it has been a few years ago since i have checked this ) and affect the running of the engine
The little thing with the 4 connections to the right is what i use to check the accuracy of the gauges by connecting them together.

The 4 hoses should connect to the 4 brass connections which have the group of 4 hoses connected that are shown in the throttle body earlier in the thread, not the three hoses group, you should be able to find the correct connectors with the aid of the t.b. picture.

What worried me about your initial question was that you wanted to connect "the vacuum gauge" whilst there are 4 required.

If you decide to do the adjustment leave one of the screws un-adjusted so it remains in the factory position, hope this helps Enzo, all the best.

[max]

Translated;
ecco cosa uso per controllare i carburatori / corpi farfallati, ho regolato gli indicatori in modo che leggano uguali quantità di vuoto (vedi le diverse posizioni dell'ago).
Ci sono diversi adattatori, quelli dritti si collegano ai carburatori cb500, quelli sopra si collegano ai due attacchi interni del corpo farfallato e gli altri 2 tubi si collegano al t.b. esterno. connettori per il vuoto.

Il set di tre tubi flessibili sono collegati alle stesse camere ma devono rimanere collegati perché misurano il vuoto per l'e.c.u. (penso, sono passati alcuni anni da quando ho controllato questo) e influiscono sul funzionamento del motore
La piccola cosa con le 4 connessioni a destra è quella che uso per controllare la precisione dei calibri collegandoli insieme.

I 4 tubi dovrebbero collegarsi ai 4 raccordi in ottone che hanno collegato il gruppo di 4 tubi che sono mostrati nel corpo farfallato in precedenza nella filettatura, non il gruppo dei tre tubi, dovresti riuscire a trovare i connettori corretti con l'aiuto del tb immagine.

Quello che mi preoccupava della tua domanda iniziale era che volevi collegare "il vacuometro" mentre ce ne sono 4 richiesti.

Se decidi di fare la regolazione, lascia una delle viti non regolata in modo che rimanga nella posizione di fabbrica, spero che questo aiuti Enzo, tutto il meglio.

[Enzofour_imp]

Translated;
ecco cosa uso per controllare i carburatori / corpi farfallati, ho regolato gli indicatori in modo che leggano uguali quantità di vuoto (vedi le diverse posizioni dell'ago).
Ci sono diversi adattatori, quelli dritti si collegano ai carburatori cb500, quelli sopra si collegano ai due attacchi interni del corpo farfallato e gli altri 2 tubi si collegano al t.b. esterno. connettori per il vuoto.

Il set di tre tubi flessibili sono collegati alle stesse camere ma devono rimanere collegati perché misurano il vuoto per l'e.c.u. (penso, sono passati alcuni anni da quando ho controllato questo) e influiscono sul funzionamento del motore
La piccola cosa con le 4 connessioni a destra è quella che uso per controllare la precisione dei calibri collegandoli insieme.

I 4 tubi dovrebbero collegarsi ai 4 raccordi in ottone che hanno collegato il gruppo di 4 tubi che sono mostrati nel corpo farfallato in precedenza nella filettatura, non il gruppo dei tre tubi, dovresti riuscire a trovare i connettori corretti con l'aiuto del tb immagine.

Quello che mi preoccupava della tua domanda iniziale era che volevi collegare "il vacuometro" mentre ce ne sono 4 richiesti.

Se decidi di fare la regolazione, lascia una delle viti non regolata in modo che rimanga nella posizione di fabbrica, spero che questo aiuti Enzo, tutto il meglio.

Thanks Max, my vacuum gauge is like yours, 4 pressure gauges in a glycerine bath with 4 tubes for connection.
My doubt was how to connect it to the throttle body of the CB 1100.

[max]

Short update on the two 330 ohm resistor modification;

Now been riding for two weeks with the iacv disconnected and replaced with two 330 ohm resistors posted elsewhere in the forum.
Even at 13 deg C, it starts first time, idles at 800 rpm and climbs to 1000 rpm within 1 minute.
As a bonus the clutch " clunk " in first gear has almost disappeared because of the lower rev's.

Remembeing that i don't have the iacv idle problem, i just wanted to try this alternalive method out for the benefit of those who have the issue and want an easy alternative for whatever reason, in short: it works.



Make sure the resistor leads are inserted into the connector by 10 mm to get a good contact,

Thanks for everybody's help in this thread

[PowerDubs_imp]

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[Nachodaddy]

Short update on the two 330 ohm resistor modification;

Now been riding for two weeks with the iacv disconnected and replaced with two 330 ohm resistors posted elsewhere in the forum.
Even at 13 deg C, it starts first time, idles at 800 rpm and climbs to 1000 rpm within 1 minute.
As a bonus the clutch " clunk " in first gear has almost disappeared because of the lower rev's.

Remembeing that i don't have the iacv idle problem, i just wanted to try this alternalive method out for the benefit of those who have the issue and want an easy alternative for whatever reason, in short: it works.



Make sure the resistor leads are inserted into the connector by 10 mm to get a good contact,

Thanks for everybody's help in this thread

Thank you, Max. This is a very clean solution and is certainly better than spending thousands of dollars replacing perfectly good parts while trying to guess which one is faulty.

[Nachodaddy]

Max, just to verify, the resistors in post #1326 you identify as 220 ohm, and the ones you settled on in post # 1355 are 330ohm, right? And the ones I should install are the 330 Ohm? Or does it really matter?
Thanks again.
PS, I won't try this out until probably late September when the temperature in my garage drops below 90F (or 30C).

[max]

Max, just to verify, the resistors in post #1326 you identify as 220 ohm, and the ones you settled on in post # 1355 are 330ohm, right? And the ones I should install are the 330 Ohm? Or does it really matter?
Thanks again.
PS, I won't try this out until probably late September when the temperature in my garage drops below 90F (or 30C).

Completely understand Nacho, all in good time.
The resistance of one of the two windings of the iacv is around 100 ohms, the ecu checks this value constantly and if it decides the iacv has an open circuit it sets a code ( orange cel ) and puts the engine in " limp home mode" ; 5000 rpm limit.
So the ecu checks the current through the iacv windings, the minimum value resistor is 390 ohm before it sets an alarm, so any value resistor between 100 and 390 ohms is sufficient for the ecu to not set a code, the voltage across the windings is 12 volts according to my oscilloscope, so at 100 ohm the current flow is; 12:100=120 mA with a 50% duty cycle during iacv activation which is o,72 watts ( at 50% duty cycle ) for short periods of time.

So a 1 watt resistor of 100 ohm would work fine, but the same result can be achieved with a 390 ohm resistor, the power dissipation would now be; 12v x 0.03 A= .036 watts.
I tend to choose to do the job with minimal current draw but still reliable so i chose the 330 ohm resistors since they are also used to load the o2 sensor heater when unplugged, ( the ferret's o2 mod ) so it is a bit of a universal value.

So anything between 220 and 390 ohms will work equally well provided the power rating of the resistor is 1 watt, smaller than that means the reliability is compromised and the wire size of the resistor leads becomes too small to fit reliably in the connector,( 0.6 to 0,7 mm., too big a resistor would have larger wire diameters and be more difficult to insert into the connector and the connector's contacts would be splayed out too far in case it had to be re-connected to the iacv.

The 1 watt version i used fitted nicely into the connector if inserted 10 millimeters into the body of the connector, initially i did not insert them deep enough and the orange cel lit up so i re-inserted them a bit deeper at 10 mm.

Long story but now you know why .

[pdedse]

Max, just to verify, the resistors in post #1326 you identify as 220 ohm, and the ones you settled on in post # 1355 are 330ohm, right? And the ones I should install are the 330 Ohm? Or does it really matter?
Thanks again.
PS, I won't try this out until probably late September when the temperature in my garage drops below 90F (or 30C).

Completely understand Nacho, all in good time.
The resistance of one of the two windings of the iacv is around 100 ohms, the ecu checks this value constantly and if it decides the iacv has an open circuit it sets a code ( orange cel ) and puts the engine in " limp home mode" ; 5000 rpm limit.
So the ecu checks the current through the iacv windings, the minimum value resistor is 390 ohm before it sets an alarm, so any value resistor between 100 and 390 ohms is sufficient for the ecu to not set a code, the voltage across the windings is 12 volts according to my oscilloscope, so at 100 ohm the current flow is; 12:100=120 mA with a 50% duty cycle during iacv activation which is o,72 watts ( at 50% duty cycle ) for short periods of time.

So a 1 watt resistor of 100 ohm would work fine, but the same result can be achieved with a 390 ohm resistor, the power dissipation would now be; 12v x 0.03 A= .036 watts.
I tend to choose to do the job with minimal current draw but still reliable so i chose the 330 ohm resistors since they are also used to load the o2 sensor heater when unplugged, ( the ferret's o2 mod ) so it is a bit of a universal value.

So anything between 220 and 390 ohms will work equally well provided the power rating of the resistor is 1 watt, smaller than that means the reliability is compromised and the wire size of the resistor leads becomes too small to fit reliably in the connector,( 0.6 to 0,7 mm., too big a resistor would have larger wire diameters and be more difficult to insert into the connector and the connector's contacts would be splayed out too far in case it had to be re-connected to the iacv.

The 1 watt version i used fitted nicely into the connector if inserted 10 millimeters into the body of the connector, initially i did not insert them deep enough and the orange cel lit up so i re-inserted them a bit deeper at 10 mm.

Long story but now you know why .

Max, your willingness to perform exploratory surgery on your bike when you don't have the problem yourself is admirable. This makes me wish I still had my 2014 standard (which had the high idle problem) so that I could test this fix to see how it works...almost wish, I mean.

[Bazbro_imp]

Yes, you're extremely helpful, Max, on this and other matters, I've noticed. Top man!