Honda CB1100 Rough Idle Solution

[dickie1951_imp]

I have read online that several Honda CB1100 owners have experienced this problem.

For several years, my 2013 Honda CB110 motorcycle would intermittently experience a rough idle. Specifically the idle would fluctuate between 1100 RPMs and 800 RPMs at about a 2 second interval.

This occurred regardless of outside air temperature, changing fuel brands, and going from 91 to 87 octane gasoline.

The solution was to remove all contents from the small compartment under the seat that covers the battery. And to use the original seat that came with my bike.

This solution is based on regulating the temperature under the seat so that the Intake Air Temperature (IAT) sensor is not overheated. The IAT is located in front of the battery and protrudes into the Rear Air Cleaner housing.

I suspect that the dense contents in the under-seat compartment was preventing the IAT from sensing the actual air temperature. And the custom seat was not allowing enough air to circulate under the seat, again allowing heat to build-up and causing false IAT readings.

After making these two changes, I have not seen the rough idle in the last several weeks.

I hope my solution will help other Honda CB1100 owners fix this frustrating and elusive problem.

 

[Cormanus]

G’day dickie1951, welcome to the forum.

 

[peterbaron]

Welcome to the forum, dickie1952.
That makes sense from an engineering point of view .

 

[LongRanger_imp]

Very interesting. My bike doesn’t have this problem but I’m wondering if you actually resolved the issue or if it’s just a coincidence?

 

[the Ferret]

Really? That IS interesting.

 

[max]

Mr d from Minneapolis welcome to the group and thanks for your interest in the rough idle situation.
Very few 2013's have this issue so it's interesting to know your experience, please keep us posted with any new developments, all input is appreciated and helpful, thanks for your input

 

[Houtman_imp]

That is very interesting , you mentioned regardless of outside temperature it still had a rough idle. You would think that at colder temps the problem would not occur ? I hope that this is the cure for YOUR idle problem.

 

[pekingduck]

I wonder if the problem is from losing spark/fuel on one cylinder momentarily - possibly a bad connection somewhere. I wouldn't think it was a bad IAT sensor nor enough heat build-up caused by air blockage.

The airbox intake is under the right sidecover, with the inlet facing the area around the fender/sidecover/frame. It may have been a coincidence, but one way to find out is to change those things back, and do one thing at a time.

 

[Guth_imp]

It is good to finally have you on board dickie1951.

I wonder if the problem is from losing spark/fuel on one cylinder momentarily - possibly a bad connection somewhere. I wouldn't think it was a bad IAT sensor nor enough heat build-up caused by air blockage.

The airbox intake is under the right sidecover, with the inlet facing the area around the fender/sidecover/frame. It may have been a coincidence, but one way to find out is to change those things back, and do one thing at a time.

That would be my temptation, just to satisfy my curiosity.

 

[Randy B]

I see a flaw with your hypothesis. The IAT sensor does not read the air outside of the intake stream, but inside of it. Airflow around the airbox has no effect on the IAT sensor.

The bike had been sold in various countries before being released in the US, so if this was some sort of issue, I'm sure that the Honda engineers would have known about it.

 

[dickie1951_imp]

Very interesting. My bike doesn’t have this problem but I’m wondering if you actually resolved the issue or if it’s just a coincidence?

Right, that was my concern too.

That is why I tested my solution for three weeks before posting it.

Prior to removing the contents from the under-seat compartment, I would experience the idle fluctuation two or three times during a 30-minute ride.

 

[pekingduck]

What aftermarket seat did you have? Was thee pan very different?

 

[dickie1951_imp]

What aftermarket seat did you have? Was thee pan very different?

The aftermarket seat is a Corbin.

The under-side of the Corbin seat is basically smooth from front to back and left to right.

The stock Honda seat has ribs cross-hatching its under-side. Those ribs look to form channels that would allow air to flow and I guessed that might help stabilize the temperature near the IAT sensor.

 

[pekingduck]

The sensor has its probe on the inside, and only detects what air is flowing through the airbox, so it's not stagnant in there. I've got my battery/tool box/underseat area crammed full and no problems, but it's not a 2013.
Still, airflow is a tricky thing, and I'm sure the factory didn't test for stuff like that.

 

[Houtman_imp]

I also have the little box full of "stuff" , including an air compressor on all of my 3 CB 1100's AND Corbin seats on all of them as well ! Never had any idle problems so far ( now it will start ! ) I hope that your solution was good for your bike to be honest I am still doubtful if it was the cause of the poor idle.

 

[dickie1951_imp]

I want to continue my test one more week without the fluctuating idle riding in temperatures ranging from mid-60s to mid-90s. Until removing the bungee cords from the storage compartment three weeks ago, the fluctuating idle has persisted intermittently for over four years now.

Then I will cram the stack of bungee cords back into the compartment. I will see if the fluctuating idle returns.

My whole idea of the IAT sensor being involved with idle problems originated by reading posts either on this forum or others.

 

[Cormanus]

Keep us posted, dickie. All contributions to this problem are welcome.

 

[Houtman_imp]

Dickie1951 , thank you for trying to find an answer to your dilemma , I was born in 1950 , you were born in 1951 ?

 

[dickie1951_imp]

Dickie1951 , thank you for trying to find an answer to your dilemma , I was born in 1950 , you were born in 1951 ?

Yes, my first big bike was a new 1971 Honda CB750.

My CB1100 is a great upgrade to my old bike from many years ago.

I want to contribute to this forum and help others as others have contributed and helped me.

 

[Houtman_imp]

There are some VERY smart and helpful people on this Forum . Do not count me as a smart one .