WRR big fuel consumption

Hello everyone!
First of all - I live in Belarslus, so English is not my native language and I'll make mistakes)

I have WR250R for 2 years, it is californian version with fuel vapour adsorber.
Gears are stock, also no mods of exhaust, intake or anything else. Using 95 RON gasoline, 98 RON when possible.

Motorcycle was bought with ~500 km on odometer, now it is near 15000km.

All that time fuel  consumption is 4,5-6 liters per 100km at 90-100 km/h speed, depending on wind conditions. It is about 48 mpg at 60-62 mph in best case(if using american fuel gallon). So I barely can do 140-150km (87-90 miles) on full tank. Same situation takes place on lower speed.

I thought that it is normal for that bike, but I see most of people have lower consumption.
It is not popular bike in Belarus, so I have no example to compare with.

Is it normal or something is broken?
Valve clearance and timing marks meet specs, no errors on dash, exup seems to be functional.

Any suggestions?

That fuel consumption translates to 41-53 mpg, which is not only low for a WRR with no modifications, but also very inconsistent; I have full mods and I am getting 50 mpg consistently, without being gentle on the throttle.

If I'm not mistaken European bikes were equipped with a Lambda sensor, so my first thought was that it may be damaged, but you mention that you have had this problem since the bike was 500 km new, so it would be a stretch if the sensor went bad so early in its life. One way to check would be to unplug the sensor and see what kind of mileage you get. (Unplugging the sensor would probably give you a check engine light, but I suppose you could ignore it).

Another unlikely thing you could check is the fuel pressure; it is supposed to be 36 psi, if for some reason it is higher the engine would be running rich, and the mileage would drop.

If those experiments don't yield any meaningful results, the only way you can really check is to take it to a tuning shop where they can measure the air/fuel ratio.

No lambda sensor. It is californian version. Also I see no lambda on european one sent in Russia. Fuel pressure is 2,6-2,7 MPa, seems to be normal. Also I can check AFR by myself, after I figure out how to install WBO in a pipe with minimum damage.
Also I don't think, that mods should be good for fuel economy. All of them are for rising power output.
More air =>more fuel=>more power

I presume you mis-typed the fuel pressure as 2.6 MPa, because that translates to 370 psi; you probably meant 0.26 MPa?

Correct, a more open airbox together with a more open exhaust and a fuel controller translate to worse fuel economy; without mods people had been reporting low-60s mpg, which translates to about 3.8 l/100km.

If you have the capability to measure AFR, then this is the ultimate test of what is going on.

Yeap, 0,26.
I think I can attach probe if I temporary turn off AIS and use its port for probe tube.
I'm good at tuning carburetors, but that undocumented efi systems make me feel like a monkey with a grenade :)

I would think that inserting the probe into the exhaust would be the easiest way to measure AFR; the spark arrester assembly in the OEM muffler is removable.

The EFI cannot be modified, so there is no concern of screwing up the OEM tune. However, that is also the major problem, that if the AFR is off you have no tuning options.

Probing from pipe will give false measurements due to catalytic converter and AIS. In any case AIS should be disabled to perform correct measurements.

Fantomosio, I have an EU version over here in Germany. Just to give you a metric reference: mine never consumed less than 4 l/ 100 km. It used to be 4.2...4.6 l/ 100km with stock gearing. My current numbers are not that good anymore, because I am lazy to properly monitore it and run 2 different rear wheels with both giving gear ratios different from stock. And I dont run a speedohealer. Only thing I can add yet: mountain and hard enduro use will bring consumption up to the lower 5.x liters/100km, however, havent noticed any higher.

Ok... I finally made exhaust composition measurements. Also I got another wrr to compare (US version w/o an adsorber). Lambda is highly dependent on air conditions, like moisture and temperature, but overall it is good. BUT! Carbohydrates level is extremely high before catalyst and ais do their work. In my opinion it is so due to the big diameter of combustion chamber and single spark plug design, so it is no full fuel deflagration. Engine must run on rich mixture to perform power output. So, it is normal...

The WRR is tuned very lean from the factory in order to pass emissions, so your finding that yours is running very rich is an indication that either something is wrong with your WRR, or someone deliberately tuned it to run rich - which would also explain the unusually high fuel consumption that you are seeing.

It is lean if is measured after catalyst and ais. I measured with ais disabled and before catalyst. I'll check it on another one wrr, but it will take some time. Trying to finish one long-lasting project right now...

So, I finally have another wrr to compare with and try to change some parts. First of all, we made side-by-side drive test. 100km trip, both motorcycles at same conditions. Mine consumed 5.5L, second one 4L. After that we swapped ECU and made same trip at another direction. Nothing changed. Both bikes have CO correction set to 0. After that I have switched dases into diagnostic mode, checked TPS, MAP, IAT and coolant sensors. All are the same (with acceptable tolerance). So, only one thing, that I can suspect, is an injector atomiser. Will swap it and check again.

Fuel consumption of the second WRR (4L/100km = 59 mpg) is what most people in this forum would consider normal for an unmodified bike; the fuel consumption of the first bike (5.5L/100km = 43 mpg) is a sign that there is something wrong with it.

Fantomiaso wrote:

So, I finally have another wrr to compare with and try to change some parts. First of all, we made side-by-side drive test. 100km trip, both motorcycles at same conditions. Mine consumed 5.5L, second one 4L. After that we swapped ECU and made same trip at another direction. Nothing changed. Both bikes have CO correction set to 0. After that I have switched dases into diagnostic mode, checked TPS, MAP, IAT and coolant sensors. All are the same (with acceptable tolerance). So, only one thing, that I can suspect, is an injector atomiser. Will swap it and check again.

Sorry for the big bump, did you ever find the reason for the poor MPG on the other bike? How did swapping the injector go?

I measured the voltage of my O2 sensor on my UK bike and it says the bike is running rich always (0.92-0.94v).

Thank you

johnkol wrote:

Fuel consumption of the second WRR (4L/100km = 59 mpg) is what most people in this forum would consider normal for an unmodified bike; the fuel consumption of the first bike (5.5L/100km = 43 mpg) is a sign that there is something wrong with it.

Did you ever fix this?

I have a low fuel mileage problem

ajnock@gmail.com wrote:

Did you ever fix this?

I didn't have the high consumption problem, I was replying to the person that did have the problem (Fantomiaso), who hasn't logged into the site in 2.5 years, so I wouldn't hold my breath expecting to receive a reply from him.