CB1100 Idle speed instability problem

[curlyjoe_imp]

This forum (Ferret I think) recommended [url=https://www.amazon.com/Sea-Foam-SF-16-Motor-Treatment/dp/B0002JN2EU/ref=pd_lpo_263_bs_t_2?_encoding=UTF8&psc=1&refRID=VCFB90P1N4H8PJHQ05HT]seafoam as a fuel treatment. I bought a low mileage ST1300 (2008) last summer and the engine was running rough and after a couple of tanks with a seafoam treatment, it was purring like a kitten. Works great for my mower, snowblower and generator too. I use it regularly every few tank fulls for both motorcycles.

[dave]

So I have the 1500rpm idle problem and I've replaced the Idle Air Control Valve (IACV) and now the engine oil temperature sensor (EOT?) as well. I also did the throttle position reset thing where you open and close the throttle a few times with the key on. So far no real change.

The bike will actually idle perfectly for a few minutes once it gets up to temperature. But then after a few more minutes of riding it goes back up to 1500rpm idle and stays there. I can't seem to figure it out. I wish I had an oil temp gauge so I could see if it's oil temperature related. Do these bikes have a thermostat for the oil cooler or anything? I wonder if the motor is getting too cold or (less likely) hot?

Hi Magnus. I am in San Diego also, with the same problems. I replaced my EOT sensor with no luck also. However, when I unplugged the EOT sensor the bike ran perfectly - maybe you can try this?

If you saw my earlier post, my WFO run "seems" to have fixed my bike. I have taken the bike on several short (less than 60 mile round trip) runs and ridden it around town and it has been running the best it ever ran. Don't ask me to explain how or why, because I don't understand what could have changed. But, try disconnecting your EOT sensor (when the engine is off) and see what happens.

[Wisedrum]

To answer the upcoming question, does the CB have a temperature related sensor in the oil cooler, my mechanic explained it that way, there' is valve which the cold oil is not able to pass to flow into the cooler. When it is warmed up to a certain degree, it only then can do so, 'cause the oil molecules have changed their diameters, somehow mutated. This creates the flow and its cooling down.

My CB sometimes idles high with a warm engine, not always. I still don't understand it.
But it has good emission values when it was checked by the TÜV a few days ago, so I don't care about it that much anymore and furthermore will wait for its fully selfhealing. Hope is the last to die...... I will not spend money on expensive parts with questionable interventions and results.

Wisedrum

[Lord Popgun]

The output of the oil cooler goes to the spark plug area and then back to the sump. The EOT sensor is in the return line from the head to the sump.

The output of the oil pump has two paths. One to the oil filter and out to the engine, transmission and all, and one to the oil cooler. The oil filter line has a relief valve called Pressure Relief Valve.

The oil from the pump TO the cooler does pass through a Relief valve (located in the pump and called Relief Valve).

On the oil schematic in the service manual in section 4, the valve is drawn such that it doesn't meter oil, just dumps it if there is over pressure. But, there is no explanation and no specs listed. It is a serviceable item though. Edit to add. I don't think it would make sense to limit flow to the cooler as the spark plug area is going to get hot fast, and that is not a good thing, thus the oil cooling there.

There are no temperature valves in the oil system shown anywhere or mentioned in the servicing procedures. Only the EOT sensor. I think your mechanic is blowing smoke. Or just figuring it works that way because some other bike does.

[Wisedrum]

My mechanic just compared it with systems he knows. He didn't worked for Honda motorbikes, although he has some.

Which ever will be the oil cooler system of the CB, as long as it works, I don't worry about it. But thanks for your detailed information.

Wisedrum

[Lord Popgun]

Wisedrum, If you PM me your email address, I will send you a scan of the oil schematic. I won't post it as it is copyright...

[Cormanus]

Thank you popgun.

[curlyjoe_imp]

I think popgun is correct. As I recall, the CB1100 engineers had a real problem with high heat around the spark plugs so it makes sense to have unregulated oil flow from the oil cooler to the channels around the spark plugs.

[PowerDubs_imp]

I always thought it was pretty neat our spark plugs have their own little cooling fins.

[Hatred66_imp]

So I did the riding WFO for a while a couple of days, and it seems to have somehow helped with the low-high idling problem (or it might be a coincidence, who knows at this point). Since I've been putting 91 octane gas from day one (thinking it was better), and that might have actually been a part of the problem, I'm moving to lower octane gas from now on.

I'm also taking the bike for service this weekend, so I'll mention the problem and all this discussion to the Honda mechanic. However, I have little to no hope on this. This is sad and disappointing from such a big brand, but based on others experience they seem to be clueless to say the least.

I'll keep you guys posted if something interesting comes up soon. For now, I'll keep doing the WFO therapy from time to time and crossing fingers when we hit 80 degrees in LA. Forecast says that will happen this weekend, so if the issue has to come back, no doubt it will be by then, when bikinis are seen around the coast.