Fuel Injected Bikes And MPG/Km/L

[Bob_Roller]

Don't know how many other members here have bikes with fuel injection, but here's an observation that I have seen with my oilhead .

BMW recommends premium grade fuel for the bike .

During the 'hot  season', I need to use premium grade due to detonation .

The oilhead has a low fuel level warning, activated by a float switch .

Using regular grade fuel, the low fuel light comes on at 172 miles, quite consistent, within a two or three miles .

Using premium fuel it comes on at around 194-198 miles .

Figuring out the cost per mile, it actually is more cost effective to use premium grade fuel, over regular grade .

Any one else with different make bikes with fuel injection notice this

[Lucky_Lou]

My K has roughly 2X the horsepower and weighs 1/2 as much again as the R65  but it does marginally better mpg and would leave the R65 in its wake (and probably any R series) on mid range acceleration, runs on regular unleaded with low fuel warning it does not get that hot here so i have never had a problem with pre ignition. It is a different animal to ride and as i am back on the R65 due to the slide the other day i am reminded just how good the handling is.
Lou

[Barry]

There can't be 14% more energy in premium fuel so it must be that the engine is burning it more efficiently.

Does the engine have knock sensors and adaptive ignition timing ?  That would explain some improvement but 14% is huge. On the other hand if it had knock sensors it wouldn't ping on Regular.

It's a puzzle.

I don't see any measurable improvement at all using higher octane fuel in an airhead.

[Bob_Roller]

I don't think the engine has a knock sensor, if it does, it doesn't do a very good job, it has two crankshaft position sensors (Hall Effect), used for ignition timing .

Plus an oxygen sensor in the catalytic converter area, from what I've read, the oxygen sensor plays a big role in the increase in fuel mileage with premium fuel .

I use premium fuel in the R65 during hot weather due to detonation and I see no difference in fuel consumption .

[nhmaf]

The Bosch Motronic system on the oilheads - at least those prior to the last year or so, do not have a spark knock sensor, which is rather odd.  It also uses a throttle position sensor for the left cylinder and none at all for the right one (and assumes that the two are exactly the same - hence the need for careful balancing to avoid the surging problem).   In spite of this very minimalistic approach, it can adjust the fuel metering rate based on the O2 sensor feedback, and perhaps also on the crank position sensor (in cases of severe knocking a momentary change of RPM could be detected).  So, it does adjust continuously to try to get the right balance of O2 readings and avoid gross knocking.   With the increased anti-knock rating of the premium fuel, it isn't too surprising that it can achieve a 10% advantage to me.   I'd expect they could do even better with a more sophisticated system with more sensor inputs, but as we see with the German philosophy on our old airheads, they have a strong tendency to include what is needed, but no more, as far as electrical bits go.

[Bob_Roller]

I've never checked the synchronization to the throttle bodies on the oilhead, 45,000 miles and no issues yet .

I may check it, the next time I do a synch on one of the other bikes  .

The one thing I have learned about bikes with fuel injection, if the engine starts 'acting odd', replace the battery, 95% of the time a battery past it's prime, will cause engine issues .

A couple of co-workers that ride fuel injected Harleys, say the same thing .

Batteries live a short life here in the incessant heat of the desert southwest US, compared to more temperate regions of the world .

[nhmaf]

If you aren't getting surging I'd say don't mess with it - with the fuel mileage you are getting it can't be far off in any case

[Bob_Roller]

I had mild surging for a few years, but I can't detect it anymore .

It was evident at slow speeds 45 mph and below .

[Red_Hen]

I use non oxygenated premium where I can find it.  If I'm in the SouthWest or West, I like Shell V Power - I've had bad gas in my K75s (fuel injected) and the performance really dropped off.

I've been to Shell events where they have visual comparison of valves running on cheap gas versus Shell V Power and the valves are much cleaner w/out deposits than with no name fuel.

At the very least, I always go with top tier gas - check out www.toptiergas.com

They make reference to cars but engines are engines and small engines are more sensitive to bad gas:

Here's what's on the home page:
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