I am preparing to leave South America and head for Africa, Cape Town to Cairo. It was suggested that I install a low octane "relay" that changes the timing/advance for low octane petrol. I have a 2002 1150 GSA, which typically does very good with low quality gas, in S. America anyway.

Do I need this?

Thanks for the help!
Mike

__________________
Left Seattle March '09 for RTW trip.
'02 BMW 1150 GSA

I would also be interested to know if this is worthwhile and effective on the modern bikes with the option of adjusting ign timing, not just GS1150. Or does most efi cope well enough in the standard setting with low octane - as I found on my (non-adjustable) 660Z one time.
Specifically does fuel consumption improve significantly in the retarded mode at the cost I presume of a little power?

Chris S

__________________
Adventure Motorcycling Handbook 8 • Morocco Overland 3 • Overlanders Handbook 2 • Twit

I run a 640 with the switchable ignition and found that while running in low octane setting the bike is less efficient all around...

03 640A 25.5 Liter Tank..

Low octane setting:Noticed a slight performance loss and about 415-425 KM to reserve...

High Octane: Good performance and about 450-470 KM to reserve...

I used to switch it over to low octane whenever I could not get 90+ octane for the bike, now I don't bother and just leave it in the high setting with no ill effects.. I will use it in a situation where your stuck using questionable, say 70s octane fuel...

Makes me think of two things:

1. Just how low can octane ratings go?

2. When buying fuel on the side of road, out of a can, bottle, or whatever, there is no way of knowing what is being served into the fuel tank

__________________
Dave

I'm no expert but the 'low octane' fuel setting on a 640 Adventure retards the ignition to stop knocking - pre-igniting the fuel which can burn out the piston.

As the timing is not optimal power and therefore mpg will be worse.

but what would you prefer?
- reduced power and worsened consumption or
- a melted piston?

I went for the 'better to be safe than sorry' option.

The worst consumption I ever got was 32 mpg (11.3 km/l) in Bolivia on crap fuel 80 Ron and sea level jets at 15,000 feet. Not a great combination. (Norm was 60 mpg, 21 km/l)

I believe most modern fuel injected bikes have a knock sensor to automatically retard the igintion when the fuel is of low quality.

__________________
Jerome

fowb.co.uk

let's apply a bit logic ... regardless of who's dispensing fuel. all gasoline has to come from a modern refinery. which has strict controls in place for octane and purity.

it's what happens to fuel after it leaves refinery that makes it suspect. world class outlets owned by Amoco, Exxon, Texaco, etc. delivers world class fuels.

what if say some kerosene gets mixed with gasoline? then high compression engines without knock sensors can sustain some serious damage. very rare will you get a bad tank of fuel (can happen anywhere) ... but all it takes is one if your bike has deadly combo of 12:1/no knock sensor.

the one that comes to mind is F800GS with 12:1 ... several instances has already been recorded of engine failures... probably due to bad fuel.

if your engine has a sudden loss of power after a re-fuel.... STOP... don't try to ride it out. take your helmet/ear plugs out ... then lightly apply throttle. listen for engine knocks ... a few light knocks like applying throttle in too high a gear will not hurt your engine.

solution is simple compared to a new engine ... drain, new fuel/filter ... ride on.

__________________
R90S, R80G/S PD

doesnt matter its a 1200 gs, trans alp's, 800 gs, tenere etc,
they all use the low octan petrol special in bolivia,
maybe dont open the trottle full power on paved roads, go normal with max .120 km/h,

with my old gs 100 from 89 i fill up in africa 10 liters of gasoil,-diesel on my 43 liter HPN tank, with 30 liter petrol with low oktan and the bike runs,smoke a little bit but bring me 600km to the next destination where i can get petrol,
dont try this with the newer injection bikes,
keep the mirrows up,fredontour.de

__________________
http://img196.imageshack.us/img196/434/buchu.th.jpg

" . . .the one that comes to mind is F800GS with 12:1 ... several instances has already been recorded of engine failures... probably due to bad fuel."

__________________________________________________ __________________________________________________ _____________

Not wanting to de-rail the post, but is there anything that can help prevent poor-fuel damage in the F800? Yes, good fuel obviously

I have an F800 and it would be useful to hear how others have dealt with this problem.

YES... it's quite easy if you have been warned and know specifically what to watch out for.
note this warning is not just for F800GS... also apply to other bikes with 12:1 compression without knock sensors

the word detonation immediately brings out all sorts of technical mumbo jumbo.... differences between detonation and pre-ignition, has it been remapped,.... etc, etc, etc.

then compound that with most folks wear full face helmet, some with ear plugs. then add tendency to want to ride it out, when our engine stumbles.

high compression (12:1) engines without knock sensors, has only what's between your ears to keep from destroying itself. in the unlikely event of a bad load of fuel with diesel mixed in. let's say a mama fuel vendor pumps gasoline and diesel from 55 gal barrels. then uses the same container to measure/dispense different fuels. or same 55 gal barrel held diesel, then filled with gasoline. it doesn't take very much diesel mixed with gas to effect octane.

most reliable sign of engine detonation/pre-ignition (knocking) is a loss of power! regardless of what is causing your engine knocks a loss of power will result.

DON'T RIDE ON .. STOP! multiple things can cause a loss of power. but if you experience a loss power immediately after refueling, odds are it's fuel related.

take your helmet/ear plugs out. then lightly apply throttle. if you hear engine knocking, drain bad fuel out... put new fuel in, then allow engine to idle only, until contaminated runs out. no big deal... on your way

engine gets the all clear, after you can apply full throttle without knocking. much rather get a dead motor, then one that still runs until it destroys itself. $2,500+ damages could financially end trips.

IMHO BMW should have never released a GS bike without knock sensors. knowing with history of GS bikes. some buy GS bikes for Starbuck trips, but some folks buy a GS bike to travel the world.

and yes ... I've already been slammed a few times for trying to get this warning out. note in no way shape or form am I saying F800GS is not an excellent bike. just that it has NO knock sensor to protect 12:1 engine, if you should get a bad load of fuel.

do a search on ADV and HUBB ... multiple instances of destroyed F800 engines from bad fuel ... including instances of destroyed engines from bad fuel in USA. odds are less, but one can get a bad load of fuel in America or anywhere else.

odds are if they had the benefit of above ... they could have STOPPED...drained bad fuel, idle out contaminated fuel, be on their way

__________________
R90S, R80G/S PD

Useful info.

Can I assume there's nothing I can do before the bad fuel goes in to help prevent the ill effects before they happen? No preventative measures?

short of changing bike... NO ...remapping will not help. please keep in mind getting a bad of load of fuel is highly unlikely.

LOTS of folks log thousand of miles with F800 and never get bad fuel. but now that you know to STOP, don't ride on if you experience a loss of power after a refuel ... odds are engine failure from bad fuel/engine knocking will NOT happen to you.

__________________
R90S, R80G/S PD

Thanks for the info