Which octane is best for my 2011 suzuki s40? The dealership says you can use 87 but "it likes 91". The manuel says atleast 87. I have ran 1 tank of 87 octane and it ran good. I put 89 octane in it and seemed to run better. I last filled up with 91 but havent ridden since. Does anyone know what is best for the bike?

thanks

Regular unleaded...
Any performance gain from higher octane in this bike will be imagined, it just doesn't have the compression to require anti-knock additive.
... and fuel without added anti-knock additive, naturally has more burnable fuel in it... (only a small difference, but.. more)...
Higher compression engines don't use high-octane gas because it makes more power,... they use it because the regular gas would pre-detonate at the compression level they are using...

The higher the octane, the less tendency it has to detonate. Detonation is when a fuel will auto-ignite - that means it will ignite from heat and compression alone, without spark. This only happens on higher-compression engines. If your engine doesn't have a high enough compression ratio, higher octane gas will not make your bike run better. In fact, it's possible your bike will have less power because engines typically run with a small bit of detonation which creates multiple flame fronts - this means the fuel ignited in multiple spots, not just from the spark.

In short, no, you can not damage an engine with high octane gas. High octane gas doesn't burn hotter, it doesn't contain more energy, it doesn't burn cleaner; it just resists detonation. That's it.

Thank goodness I finally found a website were people understand what higher Octane fuel is for.  I hate hearing false rumors about higher octane fuel burnng hotter, making more power, etc.....when I know it doesn't.

Running regular is fine.......run some 89 if you want when the summer temperature goes over 90......but you may not have to.  The thing to listen for is "detonation"- if you hear it when you roll on the throttle under a load it means the mixture is wrong or the fuel is too low of octane.

 
I still run regular gas.   In NC regular means 10% ethanol by law, and ethanol effectively raises the overall knock rating of the fuel (it is listed in the anti-knock additives on our listings) even as it reduces the regular fuel's energy potential (alcohol is a thinner, weaker, cooler burning fuel compared to gasoline).

Unless you put in a hot high compression piston you really don't need to run premium gas in a Savage.

Premium gas around here has sat around in various tanks for a VERY LONG time -- nobody ever buys it, so it isn't fresh gas by anybody's guesstimation.

Yeah, higher octane is to inhibit predetonation in cases of either high compression or high heat.  The compression in our bikes is not sufficient to warrant it.  I have considered using higher octane in the heat of summer but I'm not sure whether riding my air-cooled single in 100+ degree TX heat is sufficient to require the higher octane or not.  I have not noticed any knocking or pinging though.

When it comes to non-ethanol fuel, if I had it available, I believe I'd use it... at least in my bike and any small engines like lawnmowers, chainsaws, etc.

Nothin wrong with a little slickum in the pushmoline,,

WD wrote on 04/23/12 at 15:41:25:

Yeah, I used to run a little MMO in previous bikes every now and then.  Haven't done it in this one yet but probably will start, now that it's been brought back to memory.