Honda CB1100 Rough Idle Solution

[1973cb750]

Thanks for the suggestion. I will add it to the list of possible next solutions should my latest fixes in post #34 not hold up.

I have never had a fast idle problem. My idle problem has always been: oscillating from 1100 RPM, then down to 700 RPM, and back up to 1100 RPM every second or two. This would continue for as many minutes as it took for me to return home and shutdown the bike.

I’ve been experiencing this same issue with the 1100-700 idle on my 2014 CB1100. Someone mentioned low idle could be vacuum leaks so I started checking tubes, hoses….when I discovered that all 8 screw clamps that connect throttle body to intake were loose, I’m talking 8-10 turns each before they felt like they were tight. Time will tell, but ever since idle has been steady at 1k, no oscillating. Maybe combination of heat and vibration causing leak???
Will try to attach pic of 1 side which will show 4 of 8 screw clamps that I’m referring to.

I’ve been experiencing this same issue with the 1100-700 idle on my 2014 CB1100. Someone mentioned low idle could be vacuum leaks so I started checking tubes, hoses….when I discovered that all 8 screw clamps that connect throttle body to intake were loose, I’m talking 8-10 turns each before they felt like they were tight. Time will tell, but ever since idle has been steady at 1k, no oscillating. Maybe combination of heat and vibration causing leak???
Will try to attach pic of 1 side which will show 4 of 8 screw clamps that I’m referring to.
had that happen on alot of my bikes good catch

[CBob1963_imp]

Thanks for the suggestion. I will add it to the list of possible next solutions should my latest fixes in post #34 not hold up.

I have never had a fast idle problem. My idle problem has always been: oscillating from 1100 RPM, then down to 700 RPM, and back up to 1100 RPM every second or two. This would continue for as many minutes as it took for me to return home and shutdown the bike.

I’ve been experiencing this same issue with the 1100-700 idle on my 2014 CB1100. Someone mentioned low idle could be vacuum leaks so I started checking tubes, hoses….when I discovered that all 8 screw clamps that connect throttle body to intake were loose, I’m talking 8-10 turns each before they felt like they were tight. Time will tell, but ever since idle has been steady at 1k, no oscillating. Maybe combination of heat and vibration causing leak???
Will try to attach pic of 1 side which will show 4 of 8 screw clamps that I’m referring to.

I’ve been experiencing this same issue with the 1100-700 idle on my 2014 CB1100. Someone mentioned low idle could be vacuum leaks so I started checking tubes, hoses….when I discovered that all 8 screw clamps that connect throttle body to intake were loose, I’m talking 8-10 turns each before they felt like they were tight. Time will tell, but ever since idle has been steady at 1k, no oscillating. Maybe combination of heat and vibration causing leak???
Will try to attach pic of 1 side which will show 4 of 8 screw clamps that I’m referring to.
had that happen on alot of my bikes good catch

I’ve been experiencing this same issue with the 1100-700 idle on my 2014 CB1100. Someone mentioned low idle could be vacuum leaks so I started checking tubes, hoses….when I discovered that all 8 screw clamps that connect throttle body to intake were loose, I’m talking 8-10 turns each before they felt like they were tight. Time will tell, but ever since idle has been steady at 1k, no oscillating. Maybe combination of heat and vibration causing leak???
Will try to attach pic of 1 side which will show 4 of 8 screw clamps that I’m referring to.
had that happen on alot of my bikes good catch
Finally got pic to upload. So far bike is running better than ever!

[Nachodaddy]

That was one of the first things I checked and corrected when my slow-fast idle problem started. It helped, but didn't solve the problem. Different problems, different solutions.
I still have an extra set of spark plug wires and coils which one member claimed solved his problem. Never tried them, as the new ECU did solve my problem.
It seems there are as many idle problems and solutions as there are CB1100s.

[peterbaron]

That was one of the first things I checked and corrected when my slow-fast idle problem started. It helped, but didn't solve the problem. Different problems, different solutions.
I still have an extra set of spark plug wires and coils which one member claimed solved his problem. Never tried them, as the new ECU did solve my problem.
It seems there are as many idle problems and solutions as there are CB1100s.

Minus my two CBs.
They run flawlessly!

[Nachodaddy]

That was one of the first things I checked and corrected when my slow-fast idle problem started. It helped, but didn't solve the problem. Different problems, different solutions.
I still have an extra set of spark plug wires and coils which one member claimed solved his problem. Never tried them, as the new ECU did solve my problem.
It seems there are as many idle problems and solutions as there are CB1100s.

Minus my two CBs.
They run flawlessly!

Minus my two CBs.
They run flawlessly!

As it should be, Peter. As it should be.

[CBob1963_imp]

Time will tell if this fixed the idle problem, so far so good tho.
The ECU replacement, is that a plug and play deal, or ???

[Nachodaddy]

Time will tell if this fixed the idle problem, so far so good tho.
The ECU replacement, is that a plug and play deal, or ???

Yes, just unplug and remove the old one and plug in and bolt down the new one.
I wouldn't do it unless you had a really bad idle problem. A new ECU from Partzilla is $500. My idle went to 2000 and stayed there. It doesn't sound like you have a very bad problem. I think you took care of it with tightening those screws. Don't fix if it ain't broke.

[CBob1963_imp]

Thanks Nacho! I was just curious about the ECU, I have not experienced the high idle stuff at all, just the low oscillating idle, which seems to have cleared up so far.

[dave]

I thought I would put my two cents in here: All of the above mentioned tests / fixes I tried (except replacing the ECU), and until I replaced the IACV none of them worked. Several times I thought I had resolved the high / low idle speed, only for it to come back again. IMHO, the "fixes" that really seem to have worked for most of us are the IACV replacement, and the ECU replacement. But it's great to hear all of us joining in, working as a team, and supporting each other to resolve this challenging issue. Wouldn't it be great if Honda made an official, public statement, clarifying exactly what the root cause of this issue was, and offer all of us a public apology, and even some kind of compensation for all of our time and expense? I am sure that by now, Honda knows EXACTLY what the root cause of this is, and the solution.

[the Ferret]

If im not mistaken*, in Europe, there was an official reflash of the ECU available to cure the problem. It was never offered or made available here in the states, so our only resort was to buy and replace the ECU with an ECU with an updated part number.