100 octane petrol OK?

Now, now, there's no need to get nasty just because you are hopelessly and
utterly out of your depth on this matter. I suspect that you are neither an
engineer nor chemist.

"A practical measure of a fuel's resistanced to knock is obviously required.
This property is defined by a fuel's _octane_number_. It determines whether
or not a fuel will knock in a given engine under given operating conditions:
the higher the octane number, the higher the resistance to knock. [...] A
fuel's octane number is determined by measuring what blend of these two
hydrocarbons [heptane and isoctane] matches the fuel's knock resistance."

The above was taken directly from Chapter 9 of "Internal Combustion
Fundamentals", by John B. Heywood. This book is widely acknowledged as a
"bible" on the subject.

 

True. But, since it ran fine before... you should see fazer - it really does
nothing at such low RPM's....
it's not that it doesn't "pull like nuts" at 3-4k RPM, it's that when i open
throttle, you can feel that engine is sufficating appr. 1 sec, then it
starts to pull max. it can under given conditions.
I guess i'll try this fuel one time and see if there's any
difference....today i hope - since for now it's sunny, even if they
announced rain...
Note that i DON'T need any extra power - god knows, i have it too much
already...- i just want engine to run like it should, and i don't want to
look like an idiot when coming to a service with (maybe ?) so stupid
question...

 

I think the key to your argument is that mods have to be made to the
ignition and carburation. We're talking about a standard Z750S here, not a
modified one. Putting 100 RON in the tank will not magically make it go
better.


[...] other bullshit snipped.

 

No it doesn't. Stop spreading untruths. It just has more
anti-knock compounds.

Now, the opposite may be true -- a fuel with higher BTU/lb _may_ have
a higher octane rating but that's a bird of an altogether different feather!

--
Ivan Reid, Electronic & Computer Engineering, ___ CMS Collaboration,
Brunel University. Room 40-1-B12, CERN
GSX600F, RG250WD. "You Porsche. Me pass!" DoD #484 JKLO# 003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

Well, the lower the octane rating, the faster (generally) the fuel
can burn -- tetra-ethyl-lead etc. work by slowing the rate at which the
flame front can spread. IIRC Honda's 5-cylinder 125 ran at 21,000 rpm
and needed 50-octane fuel. (Obviously technology has moved on a lot since
then...)

For anecdotal evidence, in Oz in the 70s we had two grades of
fuel, standard and super -- I think standard was 85 octane and super was
95 but I've no idea which scale was used. Anyway, my little two strokes
always used to run that teensy bit faster and crisper with standard
(remember that a 2-smoke's effective compression ratio is/was around
6.5:1), and of course suffered far less lead-fouling of the plug(s) than
with super. Standard was cheaper, too, a consideration for a poor student
with just $2/week pocket money.

--
Ivan Reid, Electronic & Computer Engineering, ___ CMS Collaboration,
Brunel University. Room 40-1-B12, CERN
GSX600F, RG250WD. "You Porsche. Me pass!" DoD #484 JKLO# 003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

To say that a two-stroke's effective compression ratio is that low
is like measuring a four-stroke's ratio from the close of the inlet valve,
i.e. wrong. It's all covered in that famous Aussie tome, Performance Tuning
in Theory and Practice, by A. Graham Bell.

 

Really ? Then please explain the chemical difference between the two
fuels that creates the anti knock /anti detonation property that is
measured by the octane rating.

JL
(here's a hint, ceteris paribus ,you release more energy when you tear
apart a molecule with more bonds)

 

John Littler wrote:

A load of crap it seems, I just learnt something though, thanks Ivan.

JL
(but I thought it was true and this *IS* usenet <sigh> I'll shut up now)

 

The real answer to your question is that you will most likely get some
benefits from using the higher octane fuel. Most FI engines will adjust
within a range to accommodate diff fuel types, so you will get the benefit.
The z750s has a fuel High octane fuels do have a higher specific energy
rating. For some reason, people seem to get emotional about this simple
fact, probably because they just want to justify buying lousy fuel, or
perhaps they have bikes that just can't adapt to it. Also, most high octane
fuels like Shell Optimax will also burn cleaner and are better for the
engine. The Shell website explains most of this stuff, so I would advise
anyone wanting to flame me to flame them instead.

 

ROFL

That extra power comes from a combination of the ignition advance and the
increased jet diameters (allowing more fuel to reach the cylinders) and the
derestricted airbox - you could also put race cans on to improve gas flow.

The higher an engine's compression, the greater the risk there is of
detonation (knocking) occurring. Hence, high compression engines require a
fuel with a higher Research Octane Number (RON) to prevent this happening.
There is no more chemical power available in the fuel. Race engines power
comes from their ability to rev high and their high compression; hence the
high octane number required to offset the increased detonation risk.

Pete understands what's going on.

 

Av gas is still leaded so if you put it in your bike you shag the catalyst
if you have one installed

 

rubbish
the word octane is derived from isooctane which was one of the first things
added to increase the ignition point under compression i think heptane was
another
(although i could be wrong )

 

Well said, Yannick. No flames or puns of flames nessesary -
Bob Nixon, Chandler AZ
01 Sprint ST "RED" 45K miles

 

So what? No one who runs at the track gave a rats ass. WhAt... You're
gonna run your Goldwing or BMW on the track using leaded fuel

Ever heard of a non sequitur? You just made one
Bob Nixon, Chandler AZ
01 Sprint ST "RED" 45K miles

 

but were talking road bikes here not racers

 

SEND SOME THIS WAY!!! This ethanol CRAP that they have here with its measly
91octane isn't worth the match to burn it with! Gotta spend over $5 a gallon
for the Cam 2 Race gas(105octane)! What is the pound/dollar exchange?

 

about $1.85 =£1.00

fuel prices circa £4.00 per gallon $7.40 standard 95 RON fuel

105 Octane is not readily available in the UK .

 

Sounds logical...since it's full of electronics, it should do that...as
said, i'll try to fill 100 oct once or twice and then see.

 

so, in short, a bit of squeezing hard won't hurt...

 

De nada. Pass it on if and when.

--
Ivan Reid, Electronic & Computer Engineering, ___ CMS Collaboration,
Brunel University. Room 40-1-B12, CERN
GSX600F, RG250WD. "You Porsche. Me pass!" DoD #484 JKLO# 003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".