CB1100 Idle speed instability problem

[736cc_imp]

Honda does not recommend high-octane in the CB1100 owners manual. Look at your plugs if you run premium in a motor that recommends low octane, they will have deposits from unburnt high-octane additives designed for high compression and hotter burning combustion. I’ve seen them on my plugs back in the day when I ran high octane because I thought if it costs more, it must be better. Trust the engineers that designed the motors requirements.

 

[Houtman_imp]

I will check the plugs on my 2013 this weekend and will give you an honest opinion !

 

[Houtman_imp]

I just pulled the two outer plugs on my 2013 with 10048 miles on them.
They look absolute perfect and it seems that running 93 octane for all those miles has not been detrimental to them.
I therefor will continue to run 93 on my bikes and other gas engine equipment.

 

[SportsterDoc]

I just pulled the two outer plugs on my 2013 with 10048 miles on them.
They look absolute perfect and it seems that running 93 octane for all those miles has not been detrimental to them.
I therefor will continue to run 93 on my bikes and other gas engine equipment.

If you avoid short trips and frequently run at higher speeds, you will be less likely to incur carbon buildup.

 

[Houtman_imp]

I never run less than at least 1/2 hour trips and also take Interstate trips at higher speeds , this I am certain will help to prevent carbon build up.

 

[SportsterDoc]

I never run less than at least 1/2 hour trips and also take Interstate trips at higher speeds , this I am certain will help to prevent carbon build up.

Good

My ride today was only 58 miles and 60 MPH going NW directly into a headwind felt like 90 MPH! The ride back from Corn Creek Springs, after a hike, was great. 85 MPH felt like only 55 MPH!!

If the idle issue is not mainly IACV, then it may be carbon or warpage of plastic IACV port in throttle body assembly.

 

[DaSwami_imp]

We have no such thing as high grade 87 octane. It's all cheap ethanol-laced crap gas.

I use Sunoco 90 octane ethanol free exclusively, so far so good!

 

[peterbaron]

For gas engines as per Wikipedia:

"..... Measurement methods

A US gas station pump offering five different (R+M)/2 octane ratings
Research Octane Number (RON)
The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane.

Motor Octane Number (MON)
Another type of octane rating, called Motor Octane Number (MON), is determined at 900 rpm engine speed instead of the 600 rpm for RON.[1] MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern pump gasoline will be about 8 to 12 octane lower than the RON, but there is no direct link between RON and MON. Pump gasoline specifications typically require both a minimum RON and a minimum MON.[citation needed]

Anti-Knock Index (AKI) or (R+M)/2
In most countries, including Australia, New Zealand and all of those in Europe,[citation needed] the "headline" octane rating shown on the pump is the RON, but in Canada, the United States, Brazil, and some other countries, the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI), and often written on pumps as (R+M)/2. It may also sometimes be called the Posted Octane Number (PON).

Difference between RON, MON, and AKI
Because of the 8 to 12 octane number difference between RON and MON noted above, the AKI shown in Canada and the United States is 4 to 6 octane numbers lower than elsewhere in the world for the same fuel. This difference between RON and MON is known as the fuel's Sensitivity,[5] and is not typically published for those countries that use the Anti-Knock Index labelling system.

Observed Road Octane Number (RdON)
Another type of octane rating, called Observed Road Octane Number (RdON), is derived from testing gasolines in real world multi-cylinder engines, normally at wide open throttle. It was developed in the 1920s and is still reliable today. The original testing was done in cars on the road but as technology developed the testing was moved to chassis dynamometers with environmental controls to improve consistency.[6]

Octane Index
The evaluation of the octane number by the two laboratory methods requires a standard engine, and the test procedure can be both expensive and time-consuming. The standard engine required for the test may not always be available, especially in out-of-the-way places or in small or mobile laboratories. These and other considerations led to the search for a rapid method for the evaluation of the anti-knock quality of gasoline. Such methods include FTIR, near infrared on-line analyzers (ASTM D-2885) and others. Deriving an equation that can be used for calculating the octane quality would also serve the same purpose with added advantages. The term Octane Index is often used to refer to the calculated octane quality in contradistinction to the (measured) research or motor octane numbers. The octane index can be of great service in the blending of gasoline. Motor gasoline, as marketed, is usually a blend of several types of refinery grades that are derived from different processes such as straight-run gasoline, reformate, cracked gasoline etc. These different grades are considered as one group when blending to meet final product specifications. Most refiners produce and market more than one grade of motor gasoline, differing principally in their anti-knock quality. The ability to predict the octane quality of the blends prior to blending is essential, something for which the calculated octane index is specially suited.[7]....."


or Octane rating - Wikipedia

pb

 

[SportsterDoc]

We have no such thing as high grade 87 octane. It's all cheap ethanol-laced crap gas.

I use Sunoco 90 octane ethanol free exclusively, so far so good!

Ethanol free is good.
Filled up at a Costco in Denver (Aurora) this week.
Options were only85 and 91.
Filled my truck (87 required) with 1/2 and 1/2 for a 88 octane blend.

Dave, what's the word on your IACV from the dealer?

 

[peterbaron]

Ethanol free is good = I support SD statement

Ethanol free gas stations Canada/US

https://www.pure-gas.org/index.jsp?stateprov=ON

February 20, I sent request to Honda dealer in Europe re RPM fluctuation...until today NOTHING

pb

 

[dave]

Hello guys, I am back. After waiting 2 weeks for the IACV to arrive from Honda I waited another 2 weeks for the valve cover gasket to arrive (I plan to inspect the valves while I have the bike apart to replace the IACV). I spent almost 3 hours on the bike on Saturday and I don't even have the air filter housing removed yet! I spent about 45 minutes just removing the fuel tank! That fuel line connector sucks! I used pliers (against the recommendation of Honda), brute force, and finally WD-40 and finally it came apart. The black, rubber, outer piece makes no sense to me. It is completely flexible and I can't see where it is doing anything except taking up space. I should have pre-read the instructions in the manual before starting because it would have saved me time. I am flipping back and forth between about a half dozen sections in the FSM just to take pieces off the bike like the fuel tank, the rear fender (fender "A" and fender "B"), and the air filter housing. I plugged the new IACV in before disassembling anything and it appears to be functioning properly - it cycles each time I turn the key on. I probably won't have time to get back to the bike until next Saturday, but hopefully I will at least get the old IACV removed by then. I apologize, but I am not fully taking pictures and documenting every step of the way. I am working slowly and carefully, (yes, I am really slow, but I don't do this kind of work very often) and I am trying to not make this task any longer than necessary. Hopefully I'll remember how everything goes back together when I reach that point (could be two weeks before I get that far, as I am limited to only having a few hours available on Saturdays for working on it). Wish me luck!

 

[pdedse]

Here's wishing you good luck! Sounds quite involved. I hope that this does it for you; if it does, you're going to come away with an amazing story and you're going to know your bike like you never imagined--painful in part, but rewarding as well.

 

[max]

Hi Dave, i know you have seen this post before but just as a shortcut;
Valve Check On 2013

The black rubber serves as a security against inadvertently disconnecting the pressurized fuel line by preventing the "blue wings" compressing and disconnecting the line by sitting in between the wings and the pipe.
popgun advises to assemble the fitting by simply pushing it home on the pipe and the blue lock clicking home with the black rubber in place.

Don't forget the pictures of the old and new iacv together, ( several ) and to screw the piston in towards the iacv body prior to installing ( because that mistake could be the cause of some damage to the fine thread of the piston).

Thanks for testing the new iacv already and take your time.

 

[peterbaron]

Hello guys, I am back. After waiting 2 weeks for the IACV to arrive from Honda I waited another 2 weeks for the valve cover gasket to arrive (I plan to inspect the valves while I have the bike apart to replace the IACV). I spent almost 3 hours on the bike on Saturday and I don't even have the air filter housing removed yet! I spent about 45 minutes just removing the fuel tank! That fuel line connector sucks! I used pliers (against the recommendation of Honda), brute force, and finally WD-40 and finally it came apart. The black, rubber, outer piece makes no sense to me. It is completely flexible and I can't see where it is doing anything except taking up space. I should have pre-read the instructions in the manual before starting because it would have saved me time. I am flipping back and forth between about a half dozen sections in the FSM just to take pieces off the bike like the fuel tank, the rear fender (fender "A" and fender "B"), and the air filter housing. I plugged the new IACV in before disassembling anything and it appears to be functioning properly - it cycles each time I turn the key on. I probably won't have time to get back to the bike until next Saturday, but hopefully I will at least get the old IACV removed by then. I apologize, but I am not fully taking pictures and documenting every step of the way. I am working slowly and carefully, (yes, I am really slow, but I don't do this kind of work very often) and I am trying to not make this task any longer than necessary. Hopefully I'll remember how everything goes back together when I reach that point (could be two weeks before I get that far, as I am limited to only having a few hours available on Saturdays for working on it). Wish me luck!

Dave,
Relax, you did very well with reporting/documenting idle issue and we would not go that far without your great help....
We all know that this is not your skilled field,... same like me singing or playing violin = :rofl::rofl:
Before you plan to remove you fuel tank next time, make sure it is nearly empty = helps a lot...and get a small piece of wood 2x4 and wedge it between tank and frame, then disconnect fuel line...and fuel tank can be removed within a few minutes...

Good luck next time

pb

 

[dave]

Thanks for the kind words of support. I left work early today (no OT) so I could work on this. If I had known this would be this difficult I would have sold this bike - honestly. I finally got the fender "B" removed and the rear half of the air box. Ended up removing the rear wheel to make it easier to remove the fender (after disconnecting the rear shocks like the manual says). I will have nightmares dreaming of how I will ever get this back together. I don't know how I'll ever reach to the numerous clips and screws to reassembly them - I basically reached in with a long screwdriver to pry some of them off because my hands won't fit. Many of the screws you need to remove are nearly invisible and I had to physical push wires out of the way and look in with a shop light to see them to insert a long screwdriver to reach them. Even with the FSM I am struggling to even find some of the connections! Had to remove the rear engine mount to remove the EVAP canister. I honestly don't know how a mechanic does it. I still have the front air box half to remove, which is attached to the throttle body assembly and they are removed together. I can't even tell you how many wires, hoses, and clips need to be disconnected! Sorry if I sound like a weenie, but life is too short for me to have undertaken a task like this. Maybe if I was able to work on it full time it would be different.

 

[SportsterDoc]

Dave

Sorry that the IACV replaceent is so challenging, but you are doing a great service to the forum by reporting the details.

Does it appear to be any easier to replace the entire throttle body assembly?

 

[dave]

Dave

Sorry that the IACV replaceent is so challenging, but you are doing a great service to the forum by reporting the details.

Does it appear to be any easier to replace the entire throttle body assembly?

Hi Doc. To answer your question, no. I have to remove the entire throttle body assembly prior to removing the IACV, and once I do this the IACV is easily removed. The problem is my hands are too big to get to so many of the areas where there are clips, screws, and hoses to remove. It's just funny how disassembled my bike is right now (with the rear wheel removed) just to replace a single valve. I miss the good old days with carburetors that could be easily removed in the matter of few minutes. I can take the fuel tank off my 1976 C750F in less than two minutes, with no tools required. And I can fully adjust all of the valves in about an hour.

 

[SportsterDoc]

Dave

Sorry that the IACV replaceent is so challenging, but you are doing a great service to the forum by reporting the details.

Does it appear to be any easier to replace the entire throttle body assembly?

Hi Doc. To answer your question, no. I have to remove the entire throttle body assembly prior to removing the IACV, and once I do this the IACV is easily removed. The problem is my hands are too big to get to so many of the areas where there are clips, screws, and hoses to remove. It's just funny how disassembled my bike is right now (with the rear wheel removed) just to replace a single valve. I miss the good old days with carburetors that could be easily removed in the matter of few minutes. I can take the fuel tank off my 1976 C750F in less than two minutes, with no tools required. And I can fully adjust all of the valves in about an hour.

I do not have a FSM, but I am surprised that throttle body removal is required, since the IACV is to the rear of the throttle body.

How much clearance do you have, for IACV exchange, with only removing rear fender and air box?

Even if you do not have time to post now, step by step photos would benefit the forum.

 

[dave]

How much clearance do you have, for IACV exchange, with only removing rear fender and air box?

Hi Doc. I looked at the possibility of removing the IACV without removing the entire throttle body assembly first and I do not think this is possible - but I will double check. Everything is so tightly packed together it makes even seeing many of the fasteners and clips impossible without removing something else first. There is a metal clip attaching a drain hose on the bottom of the air box that I can barely even touch with my finger tip. I was able to get it off by using a long, flat screw driver to pry it off; I don't know how I am going to reattach this clip.

 

[dave]

Update: IT'S OUT! Got the IACV out of the bike tonite without removing the throttle body assembly, like the FSM instructs you to do. I removed the remaining sections of the air box, which allowed me to access the IACV mounting screws. Actually, I removed the screws in the fwd-most section of the air box and forced it to the side because there is a plug connection at the very top that I couldn't even get my fingers on unless I unplugged a whole bunch more electrical connections, and then moved the main wire harness out of the way first. There is absolutely no visible damage or any visible difference between the old IACV and the new IACV. The battery is out of the bike, so I didn't test the valve's operation by turning the key on and off, but I will do this. I expect it will cycle, because I previously heard it cycling every time I turned the key on, whether the bike was running well or not. There is something potentially wrong with the way the valve came out though. I expected the valve to have been positioned all the way to its "as-installed" location, which is the valve rotated clockwise the full length of its travel on the threaded shaft, (this is how the FSM instructs you to install the valve) but instead, it was about 1/3 of what I "estimate" to be its full travel in the opposite direction. I'll have a better idea of how far it was located from the "as-installed" location when I test the valves side-by-side. There is no damage to the threaded shaft, and I do not believe the valve slipped over the threads on the shaft to not rest in the "as-installed" location. The valve came out very easily, with no binding what-so-ever. I have about 50 miles on the bike with the IACV disconnected. During this time it started harder than normal, and the cold idle was 600 - 700 RPM, but once warmed it ran well -perfect idle (but this was only about 50 miles, over three short, around town trips). This makes me believe that the location I found the valve in is probably pretty close to the location it should be in with the engine warmed up and the valve functioning normally. So the question is this: Was the valve improperly installed at the factory, or is there an issue with either the electric motor itself, or a bad signal from the ECU that controls the valve position?