Topic approved.

Speak to Shravakumar of BPCL - 09987148001. He has been able to help me in the past in Mumbai.

I have gone down to putting normal petrol - Power / Speed 91, but I have not faced any issues. but then I dont have a sports bike, mine is just a cruiser.

Knocking is bad for the engine. Do not ride in this condition for long or you'll have blown valves, gaskets, head, etc.

1000RR or 600RR face no problem. Infact octane 97 is a waste on these bikes.
I have never faced any knocking whatsoever with shell super. Recommended octane level is 91 not 97.
Gixxer(not busa) and R1 do face this problem yeah. But it aint gonna damage the bikes in any way...u just end up gettng reduced performance !
R1 compression ratio = 12.7 : 1 very high -> will need higher octane
Gixxer compression ratio = 12.8 : 1 very high -> will need higher octane
Fireblade compression ratio = 12.3 :1 not high -> speed, power, extra premium, shell super..

The sticker on tank says minimum 95 octane. I wish shell was available in Kolkata. I remember, I used to go 10 kms extra sometimes on my pulsar, just to get fuel from shell ! and the difference was noticeable.
Blade does knock with speed 91, and R1 knocks like crazy !

what about octane boosters?? wont they work??

dude how can that be ? It says 91 on my sticker
Shell super is pure unadulterated fuel yeah. Pune has about 5 to 6 of them in every direction so getting it isnt a problem.

speed is not 91 octane at all..IMHO....

what is surprising me however is how why the octane figure on our stickers are varying ?

My sticker says 95 octane or above; but the compression ratio is just 10.5:1 which is not even high. Any comments?

from Wiki
"Higher compression ratios will however make gasoline engines subject to engine knocking if lower octane rated fuel is used, also known as detonation. This can reduce efficiency or damage the engine if knock sensors are not present to retard the timing."

Another reason why the blade shouldnt knock is that its got a sensor which senses knocking and changes its ignition timing. I remember reading that somewhere !
I dont know if other bikes have that too...

Octane rating of 95 for a 10.5:1 compression ratio is a joke
Have u tried normal fuel ?

We need someone who really udnerstand this to post here. Anyone ?

Knocking will occur in the 'Blade, the R1 and the Gixxer when you use Extra-premium, Speed or Power. Not really all that bad if you keep it under control with the way you ride. What I mean to say is that majorly, knocking will occur under high load - low rpm operation. Meaning you pull the bike in high gear from low speeds. It will also occur if you accelerate really hard from standstill or from low speeds. Avoid these two situations and you'll hardly hear a knock out of the engines on 91 Octane or equivalent.

Agree with the above with an exception. The 'Blade's comp ratio is still high enough for it to want 95 Octane though the Honda engine's knock-sensor and corrective ignition timing maps encompass a wider spectrum of situations that those on other similar bikes.

JD: Octane boosters are fine occasionally. Regular usage leaves deposits on the piston crown, valves and clogs the injectors.

Bankim, the Intruder should do fine on Extra-premium. The knocking you heard could be due to lots of reasons apart from fuel Octane rating. For example: a) the fuel quality could be bad. Adulteration with Ethanol for example drastically reduces the octane value of the fuel. b) the engine could be operating close to its high-temperature mark. Most engines become more sensitive to octane values when heated more than normal. c) and if you were riding in hot conditions, the high intake air temperature of air induces knocking. Its a matter of lowered volumetric efficiency and so lower performance that the rider tends to counter with wider throttle openings for a given response. A pretty cyclic thing that results in 'knocking' even from the best of engines.

Speed is reportedly 91 Octane but then there's no detailed info on the thing on the oil company's web-site. Extra-premium is better than either Speed or Power in my experience too.

10.5:1 should not need 95 Octane or above. One can only speculate and so the greater reciprocating inertia of the relatively 'huge' pistons beating about inside the Intruder engine could probably be the source of noise similar to knocking. The Intruder tends to be used in a way that typically induces knocking - low rpm in high gears because of the oodles of torque it produces at ridiculously low rpm's. Needing to get down to 1st gear for climbing a fly-over on a bike like the Intruder can mean only two thing: 1) that you were almost at stand-still on the gradient when you tried picking up and 2) there's something wrong with your bike's engine. I have personally ridden 3 different Intruders, extensively in and around Delhi and have never experienced this issue. They were all fueled with Extra-premium.

As for the link, I'd rather put my money on what the oil companies give rather than trying out my own concoction .

Sir, Post auto policy 2010(W.E.F 01.04.2010).. Gasoline produced by the refineries are of either Euro 3(Non-metros) or Euro 4(metros) grades.
Speed91 or normal gasoline, Both should meet the specification of min.91 octane.. similar is the case for power and xtra premium.
Euro 2 grade (octane min.88) which is still available in some non-metro areas , will be completely taken out of the market W.E.F 1st october 2010.

In mumbai, Even if we fill gasoline from HP or IOC bunks..it was actually produced by BPCL refinery.. Similarly all petrol pump uses IOC's fuel in chennai..

But Speed 97 produced by BPCL's mumbai refinery is transported to all metros.

Thanks for the info Murali. The IOC website gives details of Extra-Premium through a downloadable PDF here.
Extra-Premuim is stated to be 91 RON for BSIII standard fuel being supplied to major cities now. BSII is strangely stated as 93 RON equivalent.

The BPCL web-site has details here but it states fuel grades as MS88 and MS93 and not as 'Normal' petrol and Speed.

There's little clarity by these companies about the RON/Octane status of fuels they are selling.

From what I've seen, and experienced, I'll list out my own conclusions here:

1) Octane boosters don't really do what they're called - "Boost octane". I honestly can't figure out what they do, because they have had absolutely no effect on reducing knock while using lower octane fuels.
2) Compression ratio is not the only indicator of what octane fuel must be used.
3) Lower octane fuel heats the engine up a lot more than a fuel which is closer to what's recommended.
4) Higher than recommended octane fuel is also bad for the engine.
5) More than octane, clean fuel will make a noticeable difference, and help the engine put out good performance and give you longevity.

My advice: 97 octane in SBKs is more like a placebo than anything. Get good clean premium fuel, and you'll be more than satisfied.