What AFR at idle...does it matter?

[outlawbusa]

My tune runs a good 13.2 - 13.4 all the way up the range from 1-100 throttle except at 6000 it bounces off 14 for some reason, but I noticed the other day that the AFR was really high at idle. I added fuel to the high spot and now have a sound I've not heard in a long long time. A good sound to my ears but maybe not such a good tune sound if that makes sense.

It actually sounds like a pretty good lope and the RPM's bounce back and forth a bit (about 300-400 RPMs), but running stock cams and engine.

It almost sounds like too much fuel at idle...do you tune idle to 13 or so or do you let it go as it pleases~?~

 

[mysql]

uhm. At idle there is no load. I don't see why you'd want your bike idling at 13 AFR.

I'd shoot for stoich up to 16.

 

[outlawbusa]

That probably sounds more like it...just never really thought about idle AFR before. It was sitting about 19-20 until throttle applied.

I'll turn the fuel back a bit.

 

[Professor]

I'm about 15:1 on mine. I have it set where it bumps to about 13:5 or so at a fast idle for easier warmup. From memory I added fuel in the area of the 2% 1500rpm blocks to get it there.

It doesn't gas you out from the fumes under idle that way.

I'm also running leaner 14.5-14.7 in the 5%-10% areas for cruising. Makes a ton of difference in mileage.

 

[Jacobs]

I believe "stoich" is suppose to be 14.7

 

[Professor]

I believe "stoich" is suppose to be 14.7

Correct, at least with gasoline it is 14.7

 

[mysql]

don't ask what my diesel idles at

 

[outlawbusa]

An interesting link I came across

Air-fuel ratio - Wikipedia, the free encyclopedia

 

[Commuta_Busa]

I think the last time I checked I'm in the 14 range at idle. Could be leaner since there's no load or anything.

 

[Jacobs]

I think the last time I checked I'm in the 14 range at idle. Could be leaner since there's no load or anything.

Your idle AFR isn't going to be perfect obviously whether it's a bike, car or truck on gasoline(thanks professor). They usually bounce around 14.4-15.1 at idle and at steady cruise unless you tune it leaner for gas mileage at that 10%ish throttle

 

[POWERHOUSE]

My tune runs a good 13.2 - 13.4 all the way up the range from 1-100 throttle except at 6000 it bounces off 14 for some reason, but I noticed the other day that the AFR was really high at idle. I added fuel to the high spot and now have a sound I've not heard in a long long time. A good sound to my ears but maybe not such a good tune sound if that makes sense.

It actually sounds like a pretty good lope and the RPM's bounce back and forth a bit (about 300-400 RPMs), but running stock cams and engine.

It almost sounds like too much fuel at idle...do you tune idle to 13 or so or do you let it go as it pleases~?~

Your bike should be idling at 13.2-13.5. Make sure that your clean air injection system is blocked when you are checking the A/F at idle. You guys that are seeing the higher (leaner) numbers probably have the clean air system in place, and although A/F at idle (where the engine is not loaded), is not especially critical, it can have an effect on throttle response.

 

[GSX1300R-T]

Your bike should be idling at 13.2-13.5. Make sure that your clean air injection system is blocked when you are checking the A/F at idle. You guys that are seeing the higher (leaner) numbers probably have the clean air system in place, and although A/F at idle (where the engine is not loaded), is not especially critical, it can have an effect on throttle response.

Frank is 100% correct here!!! The idle is at it's smoothest! The exhaust smell is at it's best. If you have the luxury of a 2 gas analyzer,.......the numbers are at their best too!!! My Gen 1 likes 15.5:1 to 16:1 at cruise speeds to achieve 50 mpg. Any leaner.........and it lightly surges at times,....and the mpg gets worse. As mentioned......toss that air injection system if you want accurate numbers!!

 

[outlawbusa]

Your bike should be idling at 13.2-13.5. Make sure that your clean air injection system is blocked when you are checking the A/F at idle. You guys that are seeing the higher (leaner) numbers probably have the clean air system in place, and although A/F at idle (where the engine is not loaded), is not especially critical, it can have an effect on throttle response.

Frank is 100% correct here!!! The idle is at it's smoothest! The exhaust smell is at it's best. If you have the luxury of a 2 gas analyzer,.......the numbers are at their best too!!! My Gen 1 likes 15.5:1 to 16:1 at cruise speeds to achieve 50 mpg. Any leaner.........and it lightly surges at times,....and the mpg gets worse. As mentioned......toss that air injection system if you want accurate numbers!!

The clean air system/air injection system you all are referring I am assuming is the pair valve system.

Cooincidentally I noticed this high AFR reading after removing my pair valve block off plates and putting my pair valve back on about a month ago.

Been running block off plates for the last couple years.

I'd be willing to bet you just nailed it~!~

 

[tofas2c]

Frank is 100% correct here!!! The idle is at it's smoothest! The exhaust smell is at it's best. If you have the luxury of a 2 gas analyzer,.......the numbers are at their best too!!! My Gen 1 likes 15.5:1 to 16:1 at cruise speeds to achieve 50 mpg. Any leaner.........and it lightly surges at times,....and the mpg gets worse. As mentioned......toss that air injection system if you want accurate numbers!!

He just hooked the Pair valve and i be that is what raised it back up.

 

[glenn71]

Around 13-13.2 on a gen1 is a happy idle
Air fuel.if its a built motor you certainly dont
Want a lean idle or lean cruise until maybe
60mph,if u log coolant temps youll soon
Know why.lean cruise and idle may be fine for
A stockish motor in cooler weather but
Remember leaner means a hotter running motor and
As mentioned id only do that in 5th and 6 th
Gear with sufficient airflow through the radiator.