95v98 octane

[Mr Hyosung]

This may have been discussed already, but, a mechanic of 40 years told me the other day that 98 octane was too thick for carbies. It should be only used in fuel-injected motors, and 95 for carbies. Anyone with any thoughts?

[Bastard]

Well that's a new one on me Ive been a mechanic for 20 years and have never heard or experienced this my old bike with raised compression had to use 98 or it would pink like hell (wish we still had 5 star fuel) if your running a standard or lightly modded engine 95 is what to use if you use 98 you see no performance benefit just take a hit in the wallet.

[The crow]

i only run 98 in my bikes and thats the old and the new ... 98 ive always been told to use and my last 3 bikes have all been carbie and have never had any issues i also used to wk at a refinery and never heard anything bad there but mayby theres something in it but its the first i have heard but that just humble old me

[ALBI]

yeh ive heard that the local suzuki dealer at maitland told me not to run 98 in the tls as it chews out the plugs,i only got 2500klms out of the plugs and it fried them

[Large]

Anything but Optimax used to be the story.

[BANDITROD]

I have always ran bp ultimate in my toys without any troubles

[Yella]

http://www.ksrc-au.com/Bike_Optimax.pdf

[ALBI]

quote:Originally posted by Large

Anything but Optimax used to be the story.

that was it ,optimax and ultimate from bp

[DCRacing]

Avgas for me, but i have a good supply and don't ride much :(

[Redmohawk]

To thick ? More like the mechanic was a little thick. The viscosity of a fuel based on petrol can vary but not by enough to warrent a jet change, the specific heat, latent heat of vaporisation, energy density, and specific gravity can vary quite a bit and even enough to justify a jet change , but on a well ajusted non turbo/supercharged bike the difference might be noticable on power output but I bet most would not feel it in the seat of your pants unless your a high km rider.

If you regulally ride in signifficant alittude changes of over 300 metres you may have issues with lean/rich running higher octane will generally just hurt your hip pocket in the short term, long term setup correctly it will save you cash.

[Shadowzone]

I used to have major issues with Optimax in the Blade. It would get to the second or third tank of it and start missing and shitting. Then it would take 3 tanks of regular to get it going properly again. I also had issues with BP Ultimate. So I only ever ran Caltex Vortex in the 98. Worked a treat. But Now I only run 95 and it's fine. I've also found that Shell 98 octane fuel doesn't get very good mileage in the New Kia Grand Carnival. But the BP 95 works well.

[Yella]

quote:Originally posted by yella

http://www.ksrc-au.com/Bike_Optimax.pdf



from the link,
Compatibility
Some bikes will be more suited to Optimax than others, but generally all bikes that are designed to run on
unleaded petrol are suitable for use with Optimax. Although Optimax is compatible with most bikes there may be
a requirement in some cases to make slight adjustments to the engine such as changing spark plugs, and reducing
the size of carburettor jets, or a combination of both. Bikes used mainly for city running (and therefore subject to
considerable stop-start running) are likely to need such adjustments when changed to Optimax. Some fine
adjustments may also be required to ensure that when the bike is hot it runs smoother and with better overall
performance and in particular there is more power at the top end.
Bikes that run well on Optimax without any of these changes are usually fitted with fuel injection and advanced
fuelling systems

Optimax and Spark Plugs
Your bike’s engine running richer (i.e. the proportion of fuel to air is too high) may mean that incomplete
combustion will occur and excessive carbon deposits can form on the spark plug. This situation is more likely to
occur if the bike is used around town and subject to frequent stop-start and low speed operation. This type of
operation exacerbates the situation as the engine and spark plug won’t get hot enough to allow the plug to reach
its self cleaning temperature.
Ways to reduce this problem include changing the spark plug to a slightly hotter grade (always consult the engine
manufacturer) or reducing the carburettor jets one size, to lean off the mixture. The latter is the preferred option.
Rich Running
When a bike is not tuned correctly to handle the high density of Optimax it may result in rich running. Not all bikes
are affected but carburetted bikes are more likely to suffer from running too rich, especially if they are used
frequently around town in stop-start situations. Some of the ways to overcome the bike running too rich include
changing the plug to a slightly hotter grade (always consult the engine manufacturer), reducing the jet size on the
carburettor, changing the carburettor needle, or a combination of the above. This will help the bike run well on
Optimax and allow the rider the benefits of the high octane fuel – more power, especially at the high end and an
advanced fuel additive to maximise engine cleanliness.
Jetting
Optimax is suitable for all engines designed to run on unleaded petrol. The design of the cooling system should
have no influence on the suitability of the fuel used. Carburettor fed engines may need adjustment towards a
leaner mixture but fuel injected engines with lambda sensors adjust to the higher fuel density and are generally less
sensitive to fuel density changes.

Optimax and older bikes
Optimax has a higher density than regular unleaded petrol, and therefore provides more burning power in a given
quantity and, with correct engine adjustments, better performance for less fuel. The high density of Optimax can
cause some bikes to run rich (see section on running rich) unless changes are made to the engine or the bike can
adjust the amount of fuel injected (i.e. it is fitted with fuel injection and a lambda sensor).
Older bikes are generally fitted with carburettors, (rather than fuel injection systems) which won’t actively adjust the
volume of fuel injected into the engine. So if older bikes are running poorly on Optimax it generally means they are
running rich. Reducing the size of carburettor jets or simply switching to a slightly hotter grade of spark plug can
address this issue (always consult the engine manufacturer).
Some older bikes were designed to run richer (because emissions and fuel consumption were less of a
consideration) and using a high density fuel like Optimax could lead to over-fuelling and consequently poor
running. This doesn’t necessarily have to mean less power but if a bike was previously ‘enriched’, the further
increase in fuel in the mixture might cause incomplete combustion. One way to reduce the problem is to change
back to standard jets or reduce the jet size to ensure the engine mixture is leaner


Anyway all I know is on some bikes it fouls plugs GSXR1100 my mate was running would get 100k before it needed new plugs but my old storm wasn't worried by it

[Hillsy]

Wow - I think the fact that Shell went to the trouble of making that document speaks volumes about the issues surrounding their fuel.

I've been using Ultimate in all my latest bikes - occasionally I will use Caltex 98 (no idea what the name is), but have had no problems with either of these.

I did run a tank of Optimax in my old EFE many moons ago and swore I would never touch the shit again.

[RevHead]

in my 94 gsxr1100w,,if i use 98 or optimax ,i get 120k and a set of normal plugs are fucked,,like when lkc rode his bike to AFR it was playing up so i told him to run e10,,like me im getting good economy and my plugs last 10,000ks,,work that out ,,

[Weaselman]

I'll use anything over 92 octane... and if your fuel is thick its prob'ly diesel

[fimpBIKES]

quote:Originally posted by Redmohawk

To thick ? More like the mechanic was a little thick. The viscosity of a fuel based on petrol can vary but not by enough to warrent a jet change, the specific heat, latent heat of vaporisation, energy density, and specific gravity can vary quite a bit and even enough to justify a jet change , but on a well ajusted non turbo/supercharged bike the difference might be noticable on power output but I bet most would not feel it in the seat of your pants unless your a high km rider.

If you regulally ride in signifficant alittude changes of over 300 metres you may have issues with lean/rich running higher octane will generally just hurt your hip pocket in the short term, long term setup correctly it will save you cash.


shhh, slow down 'mo
you'll scare the others off LOL


speaking of altitude, how awesome is NFR!!!!! [8D]

[oldskool]

quote:Originally posted by revheadpete

in my 94 gsxr1100w,,if i use 98 or optimax ,i get 120k and a set of normal plugs are fucked,,like when lkc rode his bike to AFR it was playing up so i told him to run e10,,like me im getting good economy and my plugs last 10,000ks,,work that out ,,

E10 in your motorcycle?
You got dropped on your head as a kid.............right?

[RevHead]

quote:Originally posted by oldskool


quote:Originally posted by revheadpete

in my 94 gsxr1100w,,if i use 98 or optimax ,i get 120k and a set of normal plugs are fucked,,like when lkc rode his bike to AFR it was playing up so i told him to run e10,,like me im getting good economy and my plugs last 10,000ks,,work that out ,,

E10 in your motorcycle?
You got dropped on your head as a kid.............right?
Dylan no mate it wont run on 98 eats plugs,,runs well on E10 and 95,,put 98 in it im walking ,,i dont like walking

[Redmohawk]

Its simple kids , tune your bike to what you want to run, if optimax is your choice once tuned to this it will run fine (better than most potentially as its more energy dense per Litre giving more power output/km pre litre) If its a highly tuned N/A motor with high comp and agressive timing or supercharged/turboed all the better BUT all lesser fuels will run a little lean in your bike and generally give you trouble.

If you can't get it reliably or run a more conservitive bike tune run 95 or other 98's as they use a better mix of fuel additives and will prob reduce valve recession , just make sure to empty your tank and carbs if storing bikes for longer than a month at the higher the RON index the more likely they will go stale when exposed to air (this includes in your tank and carbs).

Betty gets a diet of elcheapo 92 ron 4 times a week and 98 on the weekends has done over 100,000 km with me on her and had 65 on the clock when i bought her. Still going strong (mostly freeway km for hours at a time so engine temp is up oil changed every 5000 km with filter) Only ever missed a beat when she was parked for 10 weeks with stale 98 in her was a real mess to clean up carbs full of gum n shit.

[Shadowzone]

quote:Originally posted by revheadpete


quote:Originally posted by oldskool


quote:Originally posted by revheadpete

in my 94 gsxr1100w,,if i use 98 or optimax ,i get 120k and a set of normal plugs are fucked,,like when lkc rode his bike to AFR it was playing up so i told him to run e10,,like me im getting good economy and my plugs last 10,000ks,,work that out ,,

E10 in your motorcycle?
You got dropped on your head as a kid.............right?
Dylan no mate it wont run on 98 eats plugs,,runs well on E10 and 95,,put 98 in it im walking ,,i dont like walking


I wouldn't run E10 in my bike Either Dylan. I think it's shit fuel for shit motors and since I don't think my bike is shit I don't fuel it like that.

[Chase]

I found for both the ZX6R and 1100 that using 98 around town fkd the plugs and the bikes ran like shit after a while - but on long trips where the bike was getting decent runs the 98 was better performing and better mileage. So just started using 95 when I was scootin about and fill up with 98 for the weekends away.. worked OK for me.

Shell fuels are definitely the worst.

[Tony Nitrous]

I dont use E10 in anything I own.
If I had anything that didnt like BP ultimate
i'd be trying to find out why.

Not dig at anyone on here, just me.