Too rich at high speed?

Moparren

Well-Known Member
Apr 2, 2016
10
13
63
Arizona
davidsreynolds.weebly.com
After a recent freeway run I'm thinking my 2016 is running rich at high speeds. I've always noticed that mileage drops around 75 mph and on my last trip I noticed soot on a support rod for my new luggage that crosses just over the muffler.

Anybody else noticed poor freeway mileage? Would something like a power commander work? Bike is stock and I have no wish to go nuts with pipes and stuff.
 

mike5100

Active Member
Sep 5, 2017
46
16
38
UK
Yes the mpg drops by a good 20% at 75mph over tootling around at 55mph, but I think that's more a problem with physics than the engine running too rich. These are very upright bikes and the air resistance must be much higher than for a fully faired tourer for instance.
Mike
 
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Shadowjack

Active Member
Mar 15, 2018
56
14
38
Great Plains
Wind resistance varies by the square of the speed. Resistance at 60 mph is four times what it is at 30. At 75 it's 6.25 times, so it costs you.
 

belrix

Well-Known Member
Nov 2, 2015
425
215
158
50
SouthEast Kansas
I commute daily on my AT using back roads and get 45MPG running around 55MPH. Made a 2 hour run up the interstate for for 2 hours at 75MPH and mileage dropped to 35MPG!

Sent from my SM-T713 using Tapatalk
 

Moparren

Well-Known Member
Apr 2, 2016
10
13
63
Arizona
davidsreynolds.weebly.com
Wind resistance varies by the square of the speed. Resistance at 60 mph is four times what it is at 30. At 75 it's 6.25 times, so it costs you.
Totally get that and that's what I figured at first, but the luggage rack has been on the bike for a month of daily riding with no marks and the first 100 mile run to the next city and suddenly it's got soot on it. That's what makes me think that at higher throttle positions it's dumping a bit too much fuel.
 

Graves

Moderator
Staff member
Legendary Rider
Aug 14, 2016
1,245
392
173
So. Cal.
Hang a DVOM (digital volt ohm meter) with at least 10 megohm impedance on the o2 sensor and take it for a ride. If you see 0.8 to 1 volt constant it’s rich. You didn’t mention a rotten egg odor so I’m guessing that it’s not. They may have programmed it to be on the fat side during high speed, but it can’t be too fat otherwise they’d kill the cat.

After a recent freeway run I'm thinking my 2016 is running rich at high speeds. I've always noticed that mileage drops around 75 mph and on my last trip I noticed soot on a support rod for my new luggage that crosses just over the muffler.

Anybody else noticed poor freeway mileage? Would something like a power commander work? Bike is stock and I have no wish to go nuts with pipes and stuff.
 

Graves

Moderator
Staff member
Legendary Rider
Aug 14, 2016
1,245
392
173
So. Cal.
...if the malfunction indicator light isn’t coming on, ride it like you stole it.

Hang a DVOM (digital volt ohm meter) with at least 10 megohm impedance on the o2 sensor and take it for a ride. If you see 0.8 to 1 volt constant it’s rich. You didn’t mention a rotten egg odor so I’m guessing that it’s not. They may have programmed it to be on the fat side during high speed, but it can’t be too fat otherwise they’d kill the cat.
 
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ProCycle

Active Member
Oct 29, 2017
31
8
38
Oregon
Totally get that and that's what I figured at first, but the luggage rack has been on the bike for a month of daily riding with no marks and the first 100 mile run to the next city and suddenly it's got soot on it. That's what makes me think that at higher throttle positions it's dumping a bit too much fuel.
I suspect you are correct. Many motorcycles stock tuning makes them rich at higher loads/rpms for engine safety. The AT seems to take this top end richness further than others. Time for a trip to the dyno.
 

DELLA

Member
Sep 7, 2018
85
25
8
Hochstadt
Hmm , A dyno check not sure if that would help , as you won't see the effect of wind resistance on the engine loading.
All I think you will see on a Dyno is that it will then pull max revs in top gear.

Same might happen on full throttle if you can find fairly steep motorway hill. Need to be in Germany though ;)

Re Richness I wonder if the same is true on my SD06 ?
In my view it breaths slightly more freely due to the airbox and exhaust changes.

On the flat the fastest I have seen with Bridgestones but a ATAS screen is 213kmh on the GPS, 216 kmh on the original
screen and both cases that's not at full rev so for sure the total resistance holding it back is always going to mean on
full throttle that you are on the rich side. So I'm with Graves it will be on the fat side.

Don't forget if you put a rack / panniers on the bike it will increase the wind resist considerably , so to compensate you
will tend to open the throttle more , in effect the motor electronic will think you are trying to accelerate and add more fuel.
 

ProCycle

Active Member
Oct 29, 2017
31
8
38
Oregon
Any decent dyno will have the ability to dial in any load necessary. It's common to have what they call an 'eddy current' brake. Some have a 'water brake'. The dyno brake creates enough resistance to hold the bike at full throttle at any RPM. The brakes are controlled by the dyno computer. It can allow simulate real world riding resistance or it can do a step and hold sequence. Holding the motor a several specific RPM long enough for the mixture to stabilize then going to the next RPM. In addition, a good dyno shop will have exhaust gas sensors which will log air/fuel mixture data across the RPM range.
 

DELLA

Member
Sep 7, 2018
85
25
8
Hochstadt
Agreed Dyno's can do that, Yes it can be useful for a comparison.
but what is meant by "dial in any load necessary" ?

Sure I'd be interested in a Dynamic AFR reading , and would be aiming for a target stoichiometric afr on full throttle , that might be something like 12.5–13:1 for a LBT ( lean best torque ) but you only get that when you are sitting on the bike at the speed you check and with the throttle open. A practical run always takes the environmental condition ( that days on the road local barometric pressure , temperature , humidity and local altitude into account ).
Any thing else in the hall of the rolling road can and only be a guesstimation , however clever the software programming is.

I remind myself why after doing a rolling road tune following build changes to my race car ,
why I then go out and do the road tune on my Ecutek map, I have to in order to optimise for the real world / that
includes for example the air cooling rate of the airflow, and this just the reason why the tune is different for each gear.
Finally I trust my lap times and not just the Dyno.
 

ProCycle

Active Member
Oct 29, 2017
31
8
38
Oregon
...but what is meant by "dial in any load necessary" ?
It means that if you want to test the bike at wide open throttle but want to hold the motor at 5500rpm the load can be adjusted to make that happen. Kind of like having control of a variable headwind or a hill of adjustable steepness.

My old dyno (which I no longer own) had an electronic load valve for the water brake. The computer would turn the valve with a stepper motor to increase or decrease the load as necessary. There was also a manual knob so the operator could just turn it to vary the load. The amount of load you could apply to the roller was limited by the available volume of water. A 175hp Honda Blackbird could overpower my water brake up near the HP peak.

A agree that a dyno can't tell you everything you want to know about a tune. But if you suspect the AT is too rich at wide open throttle high RPM it easy to find out on the dyno. You don't be riding the bike on the road.
 

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