KLX250S on high octane!

[Paladin]

This will probably sound like a stupid noob comment but......

Have been putting higher octane fuel in the KLX on and off for a while from different sources, BUT the last 2 or 3 fills have purposely put BP Ultimate 98 Octane in it.

Out on my ride today I had a mixture of dual carriageway, stop lights, twisty hills and it suddenly dawned on me that the KLX was pulling WAAAAY better than I remember; from a standstill, through all the gears and from lower revs in higher gears!

I'm sold on BP Ultimate for the KLX now! Certainly seems much better than when running on Shell's V Power 95 Octane.

Any of you other KLX owners found the same?

[thommo77]

Interesting, Dave. I've only put in V-power to date. Might have to try the BP cocktail..........
they reckon the higher octane, the better. I didnt realise that BP was 98.

[bart]

Don't quote me on this, but I've heard that most engines are tuned to a maximum of 95 octane. Put in higher octane and it just makes for more expensive exhaust fumes.

Cold petrol runs better than warm petrol. Any fresh tank of gas on a hot day seems to run better.

Just my 2 cents.

[warewolf]

BP Ultimate 98 Octane

I didnt realise that BP was 98.

BP "Ultimate" is 98, BP's everyday Premium Unleaded is 95.

Not much Ultimate available in these parts, if any. I think Blenheim BP might be doing it now. See this from BP:
Click here for a printable list of all BP Ultimate stores in NZ (pdf, 51KB)

[Paladin]

Interesting, Dave. I've only put in V-power to date. Might have to try the BP cocktail..........
they reckon the higher octane, the better. I didnt realise that BP was 98.

If you've run V Power alot then try a FULL tank of BP Ultimate or two & let me know what you think - maybe the sun got to me today, I dunno! All I know is the bike really did feel like it was pulling way better today, faster acceleration etc. Just remember the Light Blue coloured pump "Ultimate" is 98, the yellow is Premium and is only 95.

Don't quote me on this, but I've heard that most engines are tuned to a maximum of 95 octane. Put in higher octane and it just makes for more expensive exhaust fumes.

Cold petrol runs better than warm petrol. Any fresh tank of gas on a hot day seems to run better.

Just my 2 cents.

Hadn't heard that about the tuning, certainly haven't noticed anything like that in the owners manual, just "use minimum 91 Octane". I heard that higher octane was "supposed" to improve acceleration but honestly hadn't noticed any difference when using Shell V Power 95, but going all the way up to 98 sure seems different to me! The performance wasn't just immediately after a fill when I left, certainly after being out in the afternoon sun for 120+K's it was noticeably better on SH2 away from stop lights getting near to home on the return so not cold fuel then for sure! I'm no chemist but I don't understand your cold fuel comment - surely in a combustion chamber warm fuel would ignite faster and thus performance would be better, cold fuel needs to be heated up further by the spark to ignite thus less efficient I would have thought???? Hey maybe I was just having too much fun out on the bike in the sun and just imagined it LOL! But is was fun nonetheless! Will be interesting to see if Thommo puts Ultimate in his and sees any difference.

BP "Ultimate" is 98, BP's everyday Premium Unleaded is 95.

Not much Ultimate available in these parts, if any. I think Blenheim BP might be doing it now. See this from BP:
Click here for a printable list of all BP Ultimate stores in NZ (pdf, 51KB)

Yep around Welly/Lower & Upper Hutt & up Kapiti no problem getting Ultimate, but when we go over the 'Rapa I know in Martinborough they only have the Premium 95.

[bart]

The octane thing may be more related to cars, which are generaly tuned more for economy. There was no difference in performance between 95 and 98 octane in tests I've seen.

The cold fuel theory is more to do with density. Cold liquids are denser, so with fuel you get more bang for your buck. Cold air is also better than warm air for combustion. This is because cold air carries more oxygen.

To be honest, I've never really noticed much difference between 91, 95, or 98 in my bike. I usually run 95 (this is what the manual recommends), but more for the reason of getting more range out of a tank.

I'm no chemist, so could be very wrong. If I am, I'll be filling up with 98 in future.

[Paladin]

The octane thing may be more related to cars, which are generaly tuned more for economy. There was no difference in performance between 95 and 98 octane in tests I've seen.

The cold fuel theory is more to do with density. Cold liquids are denser, so with fuel you get more bang for your buck. Cold air is also better than warm air for combustion. This is because cold air carries more oxygen.

To be honest, I've never really noticed much difference between 91, 95, or 98 in my bike. I usually run 95 (this is what the manual recommends), but more for the reason of getting more range out of a tank.

I'm no chemist, so could be very wrong. If I am, I'll be filling up with 98 in future.

I see what you're saying with the cold=denser theory!

Hmmm interesting, well we'll see if Thommo thinks his KLX likes the 98 better.

I know we were chatting on the Orongorongo ride a bit about octane and maybe it was Pete who said that he thinks or had heard that some people feel it makes no difference performance wise and some people do notice it. Maybe it is a bit bike dependent - high octane suits some bikes and maybe not others????? Maybe all dependent on the bike's set up carb/jetting/tuning wise - I dunno, am no expert in this area unfortunately!

OR maybe I'm a numpty and my bike has just hit a good patch having just past 3500km on the odo now????

[buggsubique]

I think Blenheim BP might be doing it now.

Yep, the one by Te Warewhare, not the one on the SH on the way to picton though. Mobil and Shell also have their hotstuff on tap.

[buggsubique]

Tuckerbag has a wee blog where he looks at fuel economies for different octanes. Interesting read.

http://xt400adventureriding.blogspot.com/

[warewolf]

As far as the raw octane number goes, theoretically an engine built for a particular octane will not run any better or produce any more power on a higher octane, but will likely have issues running lower. Note that one characteristic of higher octane fuel is a slower burn rate, so you do want to run with the fastest burn (lowest octane) the bike is happy with. But fuel is a cocktail of 300 ingredients, so there are other factors - can't just consider octane in isolation. Lots of stuff on the interweb about this if you are curious.

My own testing on a Honda CBX250 with a 12L tank and living a long way from the nearest fuel station, showed PULP at 17% dearer returned 25% better fuel economy, and pushed the range from 240 to 300km per tank.

A mate who runs telemetry on his race car says a person can't detect most knocking etc, it shows up on the telemetry but you can only notice it yourself when it is really, really bad. So here in NZ where PULP is only ever 5c dearer than ULP, I simply can't justify the risk of engine damage running ULP in a bike designed for PULP. Even if I can't detect it, it's just not worth the risk.

[Woodman]

I think 98 is only available on main highway centres e.g. Blenheim and not Nelson.
KLR definitely runs better on 91. It will not pull from lower revs with 95, I have experimented a few times and it is definitely so. Your 250 is probarbly a higher compression engine than my tractor and therefore would benefit.
Funny thing with the KJR though is that the mileage goes down with 91.

[warewolf]

Possibly the 91 lets you lug the engine more, aka "loaded down", which can be less fuel-efficient than spinning it along freely with a few more revs.

[Woodman]

Possibly the 91 lets you lug the engine more, aka "loaded down", which can be less fuel-efficient than spinning it along freely with a few more revs.

Either that or it actually produced less horsepower and therefore my wrist compensates with more twist.

[hayd3n]

i seem to always have gotten more (bang for my buck) out of 98 in
sr250
vt250f
vtr250 and now my
yzf600
get more ks and more power

[pete376403]

Either that or it actually produced less horsepower and therefore my wrist compensates with more twist.

KLR would probably be happier on kerosene (if you could get it at the pump)

I'd love a HDT Diesel KLR if they were 1) available and 2) affordable