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 https://en.wikipedia.org/wiki/Octane_rating

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