Really high idle

[Gordo_imp]

Today was the Cpl Humberto Sanchez escort ride from Grissom AFB to the funeral home. I'm setting this as the back drop. Temps were in the 90's and then procession was slow. Alot of 1st and 2nd gear riding in the heat. I noticed my idol was low during the ride. After the pass at the funeral home we ran a pretty spirited ride thru Logansport to Wabash. The bike then died at the light when I was taking off to make a left turn. It eventually fired and I parked it for an hour while we ate. It sat for an hour and when I fired it up the idol was was between 1700 and 1800rpms. I rode the bike home like that for 45 miles. Any ideas? I'm at a loss. No mods to the engine, stock air filter, Yosi exhaust with the quiet baffle removed.

Titus 2:13
2013 HONDA CB1100

 

[Lord Popgun]

I would suspect the IACV

 

[Gordo_imp]

What exactly is that?? Something I have never heard of.

Titus 2:13
2013 HONDA CB1100
Never mind.....just looked it up. Thanks for the reply!!

Titus 2:13
2013 HONDA CB1100

 

[Lord Popgun]

Idle Air Control Valve

Mounted on the air plenum and controls idle speed. It is a stepper motor that drives a valve and is commanded by the ECU.

Max will most likely chime in on this. We have a BIG thread on just this problem. If this is your problem, it won’t be fun to change.

http://cb1100forum.com/forum/showthread.php?tid=8120

 

[Gordo_imp]

Hoping and praying it's not. I'm actually reading that post now.

Titus 2:13
2013 HONDA CB1100

 

[max]

Hi Gordo, this valve regulates the air which bypasses the four butterfly vaves from the throttle.
It is the modern replacement of the idle adjustment screw on normal carburettors and normally works very well as you know.
What you describe is the classic situation in which it fails, my guess is that the permanent magnets inside the stepper motor lose their magnetism because of the heat and thereby the ability to operate as before.
There is also a flaw in the duty cycle ( i think ) of the software inside the ecu that does not appear in other models, the 2014 models seem to be affected the most with this situation as you probably have worked out.
Look out for some info towards the end of the thread, there is a more convenient way to replace the iacv.
Nobody has found a difference between the old and replacement iacv, not drag or anything else hence my theory of the weakened permanent magnets due to heat.
This valve operates regularly when the bike is moving, not just when it is idling.
As a positive point no iacv replacement has had any more problems

 

[Henrik_imp]

I have read all the posts on this issue before, and there are a lot, and although I do experience the same problem from time to time I have not yet done anything radical to fix it.

Since the problem for me is really intermittent, what I do when it happens is that I switch off the engine with the kill switch. Then I will open the throttle fully a couple of times, switch the kill switch back on and start the engine. After this, it has then begun working fine again. I believe the action of switching off the kill switch and opening the throttle does some sort of reset. I am pretty sure this has been mentioned on one of the many threads on the idle topic.

For sure, it does not fix the problem permanently as it then may happen again from time to time, but it has always fixed the problem for that specific ride. Something simple to try perhaps.

 

[Gordo_imp]

You guys are awesome!! Thank you all for the tips and info!! I really appreciate the help thru this.

Titus 2:13
2013 HONDA CB1100

 

[max]

Thanks for the tip Henrik, as you would have read; on every startup the ecu does not know at which position the iacv is, so it "resets" the iacv fully open and then steps it back the amount required to idle the engine at the temperature it is at that time.

You can experience this when you start the engine when this cycle is still in progress and the engine revs higher before settling down at the appropriate rev's for it's temperature.

If you have the diagnostic tool you can also observe the position of the iacv, the program indicates the position as a number in the data list and you can see it change for every "step" as the ecu adjusts it's position.

It also moves when you operate the throttle from closed as some type of "takeoff assist".

 

[furious_blue_imp]

Probably not relevant here but I'll mention it.
My long gone Harley Softail was programmed to kick into high idle if the oil temperature got above a preset limit. The idea is that with the engine on the brink of overheating they want oil circulating faster to cool the engine. Given that I'm sure that they've tested this thoroughly and it works as an emergency measure, it kind of surprised me to read about this in the manual because I would have just assumed that higher rpms automatically meant higher temps, but then this is the idle speed and the engine isn't running under a real load when this happens so I guess it makes sense. It had happened to me a few times on that bike and once traffic got moving and the engine cooled down the idle speed would go back to normal.

 

[tod.branko_imp]

Probably not relevant here but I'll mention it.
My long gone Harley Softail was programmed to kick into high idle if the oil temperature got above a preset limit. The idea is that with the engine on the brink of overheating they want oil circulating faster to cool the engine. Given that I'm sure that they've tested this thoroughly and it works as an emergency measure, it kind of surprised me to read about this in the manual because I would have just assumed that higher rpms automatically meant higher temps, but then this is the idle speed and the engine isn't running under a real load when this happens so I guess it makes sense. It had happened to me a few times on that bike and once traffic got moving and the engine cooled down the idle speed would go back to normal.

It makes sense on a Softail to a certain extent if we are talking about a twin-cam because there is a design flaw with the oil pump for the rear cylinder. From what I remember it wouldn't create enough pressure on idle so in stop and go traffic the cylinder would dry up and seize. HD have since implemented the system where the rear cylinder shuts down completely on idle and it's a system they are utilizing on the M8 even though it's water-cooled.
There is no system of that kind on the CB1100 (not officially anyways)
I heard a YouTuber once talk about a system on the CB1100 that allegedly skips a spark on random cylinders when the temperature goes too high, and I tried to find any official information on this, I even hit up a guy I know here who is a regional manager for Honda motorcycles here in the ME, and he told me that that's not the case, only cooling technology Honda is utilizing is the machining tech that allows them to cut the cooling fins thinner and longer (deeper) and that supposedly dissipates heat better.

'14 CB1100 STD 5 speed

 

[furious_blue_imp]

Probably not relevant here but I'll mention it.
My long gone Harley Softail was programmed to kick into high idle if the oil temperature got above a preset limit. The idea is that with the engine on the brink of overheating they want oil circulating faster to cool the engine. Given that I'm sure that they've tested this thoroughly and it works as an emergency measure, it kind of surprised me to read about this in the manual because I would have just assumed that higher rpms automatically meant higher temps, but then this is the idle speed and the engine isn't running under a real load when this happens so I guess it makes sense. It had happened to me a few times on that bike and once traffic got moving and the engine cooled down the idle speed would go back to normal.

It makes sense on a Softail to a certain extent if we are talking about a twin-cam because there is a design flaw with the oil pump for the rear cylinder. From what I remember it wouldn't create enough pressure on idle so in stop and go traffic the cylinder would dry up and seize. HD have since implemented the system where the rear cylinder shuts down completely on idle and it's a system they are utilizing on the M8 even though it's water-cooled.
There is no system of that kind on the CB1100 (not officially anyways)
I heard a YouTuber once talk about a system on the CB1100 that allegedly skips a spark on random cylinders when the temperature goes too high, and I tried to find any official information on this, I even hit up a guy I know here who is a regional manager for Honda motorcycles here in the ME, and he told me that that's not the case, only cooling technology Honda is utilizing is the machining tech that allows them to cut the cooling fins thinner and longer (deeper) and that supposedly dissipates heat better.

'14 CB1100 STD 5 speed

It makes sense on a Softail to a certain extent if we are talking about a twin-cam because there is a design flaw with the oil pump for the rear cylinder. From what I remember it wouldn't create enough pressure on idle so in stop and go traffic the cylinder would dry up and seize. HD have since implemented the system where the rear cylinder shuts down completely on idle and it's a system they are utilizing on the M8 even though it's water-cooled.
There is no system of that kind on the CB1100 (not officially anyways)
I heard a YouTuber once talk about a system on the CB1100 that allegedly skips a spark on random cylinders when the temperature goes too high, and I tried to find any official information on this, I even hit up a guy I know here who is a regional manager for Honda motorcycles here in the ME, and he told me that that's not the case, only cooling technology Honda is utilizing is the machining tech that allows them to cut the cooling fins thinner and longer (deeper) and that supposedly dissipates heat better.

'14 CB1100 STD 5 speed
Very interesting, I hadn't heard that about the Softail. One other major change that happened on that engine was tighter bearing clearances necessitating specs for a new oil filter for finer filtration AND a boost of the idle speed to bring up the oil pressure, which I understood was intended to provide sufficient pressure to keep the tighter bearings happy. I have seen numerous youtube videos of people doing 'cool mods' to their later model Softails which include turning down the idle speed to barely sustainable, which of course will not be good for the engine because the bearings will suffer... I wonder if the problems tended to occur with bikes that had been modified like this and Harley realized that they could change 'the culture' so they had to upgrade the pump, which they actually should have done in the first place instead of just raising the idle speed and counting on that to keep the pressure at minimum. Maybe, maybe not. It sounds more likely that the reasons you give for the new pump are true. Glad I never had THAT problem with mine !
For the 1100 cooling, don't the spark plug oil cooling circuits also help with additional engine cooling > (extremely targeted cooling for sure !).

 

[SportsterDoc]

Max, good thoughts in your post number six.
Interesting and quite plausible theory about the permanent magnets being affected by heat. If we knew the magnetic material we could look up the Curie point.

It would be most interesting to know if Honda changed the magnetic material after 2014 model... and used different in 2013.

 

[dave]

It would be most interesting to know if Honda changed the magnetic material after 2014 model... and used different in 2013.
[/QUOTE]

Hi Doc. Doesn't the Curie point temperature occur at a really high (1,000 deg F +) for common metallic materials? Are the magnets in our IACVs metallic?

 

[Lord Popgun]

This entry on Wiki has a chart of Curie points for different materials: Curie temperature - Wikipedia

 

[max]

Doc thanks for the response and good to hear from you, it occurred to me that some failures happened after riding in high temperatures, magnets loose some of their magnetic properties at higher temperatures, weller soldering irons used magnets with different magnetic properties to regulate the tip temperature, you could hear the clicks as the micro switches reacted to the tips losing their magnetism and switched the heater off and back on when the magnetism was restored.
So i thought that it was a possibility that the permanent magnets in the iacv rotor could be affected by this phenomenon.

On the other hand it is well known that updating the software has also alleviated this problem.
So i think it is a combination of software which supplied just enough energy to the iacv to make it work but as soon as magnetic force was reduced it permanently crippled the operation whilst the "good" software provided enough energy ( enough pulse with ), this is my best guess, cheers guys

 

[SportsterDoc]

Dave, it varies greatly, as per the link posted by Popgun.
Doubt we will ever know the material(s), but Max's temperature theory has merit.
Max, if only we knew the actual software update details!

4800 miles on the Street Twin since May 25 and no re-occurrence of August 2018 eye issues.

I was in two Honda dealers this week (Carter Power Sports and Rancho Power Sports), asking about any CB1100s. Was told that Honda's warehouse(s) are empty....true JIT manufacturing now.

Oh well, I am reasonably content with my 900cc parallel twin in cobalt blue.

2022 Triumph Street Twin First Look (7 Fast Facts)

As much as I resisted water cooling, it is averaging 61 MPG!

Longest one day trip was over 500 miles, from Las Vegas to Bryce Canyon National Park, Zion National Park.

 

[pdedse]

Dave, it varies greatly, as per the link posted by Popgun.
Doubt we will ever know the material(s), but Max's temperature theory has merit.
Max, if only we knew the actual software update details!

4800 miles on the Street Twin since May 25 and no re-occurrence of August 2018 eye issues.

I was in two Honda dealers this week (Carter Power Sports and Rancho Power Sports), asking about any CB1100s. Was told that Honda's warehouse(s) are empty....true JIT manufacturing now.

Oh well, I am reasonably content with my 900cc parallel twin in cobalt blue.

2022 Triumph Street Twin First Look (7 Fast Facts)

As much as I resisted water cooling, it is averaging 61 MPG!

Longest one day trip was over 500 miles, from Las Vegas to Bryce Canyon National Park, Zion National Park.

Which is just stunningly beautiful!!! Very happy for you SportsterDoc that you were able to come back to riding.

...............:biker:................................:biker:.....................:biker:.........>

 

[SportsterDoc]

Thank you, pdedse.
Good group on this forum. You all are missed!
Only a few upgrades on the Street Twin:
1. Dart Marlin fly screen
2. Givi tail rack
3. Factory center stand
4. Removed the snorkel interior, as debris was not accumulating evenly on the air filter
5. Replaced H4 with an LED: Auxito USM4H4-041: PLUG AND PLAY ON ANY H4, CLOSE TO SAME COVERAGE AS H4 BUT MUCH MUCH BRIGHTER. $19.99 from Amazon.

 

[Cormanus]

Don’t be a stranger, Doc.