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.