FOAK: Using low octane and leaded fuel

A techie Q

Down to using 84 octane in the bikes at the moment, and I suspect that it
may be unleaded ( a notice on a pump in Peru said "low lead") and Bolivia
is well... Bolivia.

Bikes are running a touch rough, but so are we at over 3800 metres

Should be in Chile tomorrow so will be (hopefully) back on higher octane
again.

What does the FOAK say ?

 

I have a vague recollection[1] that the octane is lower because of the
low oxygen density at altitude, otherwise it would be running too rich,
but wibble flip, etc.

[1]I might have heard it on NPR Car Talk.

 

Whose measurement? Given the location, wouldn't surprise me if it was US
RON+MON/2 - which comes out a lot lower than our RON. Their cooking is
87, which is about equivalent to the 91 available some places on the
continent. Their 89 is about our 95.

So that juice might be shite, but it's probably not as shite as you're
thinking it is.

 

**** nose

I know all about the ron,mon,pon crap

But 84 is *low*

And the lead ?

 

I've heard rumours of such, but with the bike being FI, does the on board
ECU not decide it needs to alter stuff ?

 

I vaguely remember lead in petrol.

There's no cat on the bike, is there?

 

Does it have a knock sensor?

 

Dunno, but it moan like **** when I drop it !

 

Easy solution to that one...

 

You are going to *love* Chile.

And Patricio & family will be fantastic hosts. Tell the bugger when you
see him, that I've saved a bottle of Longrow cask strength (courtesy of
Colin Irvine) for him and will bring it out in July.

 

No, no CAT

 

Yes, and I think I can get a new side stand cut out switch for Jean's
bike there, she had an argument with a railway line while detouring
around a classic Bolivian road block.

Will do

You sorted out a new piece of land yet then ?

 

Or an absolute pressure sensor, or an air mass flow meter?

TBH, it's likely to have the former but not the latter; bike (and many
car) ECUs tend to work on indirect airflow measurement.

 

No, but we will.

 

If it's (RON+MON)/2 that's fine at the altitude you said you were
at.

What about it? If your bike doesn't have a cat it won't matter
if there's lead in it or not.

 

Oh, and I am starting to understand why you like SA. So far I could
settle in Peru or Ecuador.

 

Can some one explain the low octane/altitude thing please ?
I've heard about it, but never understood it .

That is what I wanted to hear.

 

Can't you just permanently bypass it? It was the first mod I had to make
to the KTM after I bought it.

 

That is one plan, I have the wiring diagram now, just need to work out
where it all goes (the is a lot of mud till stuck underneath), oh, and
find somewhere with nice electrical bits... probably in Chile.

 

Higher altitude means lower cylinder pressures so lower octane fuel is
sufficient.
And the oil companies probably know what they are doing so sell the
right fuel
for modern cars, if not old motorcycles.

Reduced power goes without saying but if you have carbs you are
running rich, which might explain the rough engine.