For those that advocate using 87 octane in these bikes

[Octain]

I P!ss in my tank. Runs fine but if I plan on doing a lot of riding I have to drink a lot of beer.

[bccap]

Avoiding ethanol is probably OK, but I'm not sure that using 94 octane gas is the way to do it.

Higher-octane gas has fewer BTUs per gallon and burns slower, so you will not get any more power by simply putting it in your tank..

I'm not looking for extra power. Only to avoid the ethanol. But I'm getting the impression from some of these posts, that it may not be good for the engine ? Suzuki's manual states 85-94. Are you saying that 94 is bad for the engine?
Or just not worth the extra cost?

[Allie]

You don't need as much octane up here, as the air is less dense. Wide open throttle lets in less air than at sea level, so the tendency to detonate is lessened. 85 is enough for these low compression engines.
Another way to look at it, if you have 20% less dense air, it is exactly the same as having 20% lower compression ratio, so lower octane fuel is just fine.
It also helps that it's not likely to be 110 degrees F at 10,000 feet.
The flip side of this is we get less power, all normally aspirated engines make noticeably less power up here than they do at sea level.
The higher you go, the less power the engine can make.
A 1000 cc bike at 10,000 ft goes about like a 650 at sea level, without the high RPM kick.

Thanks. Once again, I get it after that explanation.

[1_v8_merc]

I run 100LL in my 750 sometimes, just to give it a break from that ethanol garbage.
Usually I'll just mix it with 93 octane...she runs excellent with it.
(hey the manual calls for Leaded OR unleaded 92 octane...)

The 650, I run 87, because it's a factory motor, and the manual calls for it.

[koolaid_kid]

My GS used to ping (detonate) on 87 and 89 octane. Really sucked on rallies when we got into a tiny town that only had one station and it only had 87 octane. Once I put in a Dyna S ignition and timed it with my timing light I was able to run 87 octane in it.
I only run the highest octane in the GPz because the compression ratio is around 11.00:1.

[mike_of_bbg]

I have a Pure station here in town that I try to frequent for my carbureted fueling needs. They have non-ethanol blends in 87-93. My GS has never pinged on 87. The cars with fuel injectors and high-pressure fuel pumps get whatever excuse for gas I can get the cheapest. Though, I've never had an issue with the oxygenated blends or letting gas sit in anything before except for my Honda mower. Which reminds me, it's time to drain that mower's tank and drop the contents into the Briggs-powered mower. That Briggs will drink anything.

Last time I looked at my local gas station pump, it said the Octane rating was using the (R+M)/2 method. And there's nothing available here below 87 or above 93. So it looks like I can't buy anything that doesn't meet Suzuki's requirements of 85-94?

Oh, I've also heard that ethanol (among its other properties) is an anti-knock additive, so I'd expect to find more of it in high-octane gas. Motors actually designed for pure ethanol can run much higher compression ratios than their gasoline counterparts.

[spchips]

In a carbureted vehicle not that has not had the mixture adjusted for modern fuels (richened to compensate for lower energy content), ANY regular ethanol will tend to run leaner, hotter, and might detonate. Since the 89+ gas has a higher octane rating, it is more resistant to detonation. This does not, however, do anything to improve the running hot/lean situation, and just masks the problem.

The right thing to do is sort the jetting. First of all you will probably set it a little rich just for good measure, making it run cooler than from the factory, but if the fuel in the tank is a low ethanol blend, you are now properly jetted for 10% ethanol you can run 10% Ethanol 87 all day long/oxygenated fuel and not have any problems. If you drive through an area with non blend gas, you can fill up and while you might run a little rich, at least it won't hurt your bike.

[koolaid_kid]

spchips, you may wish to reconsider your terminology. Ethanol 87 is blend of up to 87% ethanol. Around here we use Ethanol 10 in octane ratings of 87, 89, 91, 92 and 93.

[spchips]

spchips, you may wish to reconsider your terminology. Ethanol 87 is blend of up to 87% ethanol. Around here we use Ethanol 10 in octane ratings of 87, 89, 91, 92 and 93.

Post edited. I know what you mean. I live on the coast and it is unheard of to use high ethanol fuel like they do in the midwest, so i wasn't thinking about it this way.

[koolaid_kid]

Yeah, when I moved into my current house I was surrounded by cornfields. It has been built up since then, but I can still walk down the road to some.
Around here E85 is sold in select stations, and lots of vehicles are now "flex fuel" vehicles, meaning you can run pretty much anything and the computer will make adjustments as required.

[chuck hahn]

Too bad there werent GS carbs that would adjust accordingly.

[2WheelEnthusiast]

running higher octane gas in a motor that wasn't designed to take advantage of the higher octane is wasting money and hurting performance.

I just googled my 850's CR and it was 8.8 to 1, which is not even worthy of 91. My hill climbing 1000cc high compression sled running N2O was 14.3 to 1, and required 110 octane at sea level.

Now my nicer dirtbikes will get 91 non-oxy but thats just because they typically run WFO, and REQUIRE a minimum of 91 octane.

.... but in defense of the ppl wasting money on race fuel... it smells FFing awesome.

[ZakDanger]

Sooooo.... what the hell am I supposed to put in my tank? This is almost as bad as the felt vs tyvek arguments on CT.

[salty_monk]

The octane number reduces as the gas goes old too... if you're planning to leave it in the tank a while it's better to use a higher octane.

I have used all 3 grades in my Suzuki, usually a higher grade if I know I'll be out of town for a couple of weeks or something.

I live at sea level & 87 doesn't knock...

[barnbiketom]

I used to work as a line tech in a GM garage. For years when the weather got cold suddenly in the fall, we would get a slew of Grand Ams come in on the hook ( tow truck) It turns out EVERY one of them , the owners were putting in 'hi octane' gas. On the Grand Ams with higher mileage and poorly maintainenance, the resistance to ignition of the wrong gas resulted in FLOODING AND NO STARTS HAHHA. Insidethe garage ,when the car warmed up, it would always start!!! the higher the octane, the more RESISTANT to ignition. it's the compression ratio of your engine that determines octane requirements, it is not that "hi octane" puts out more power or "runs better ". people at the pump are simply uneductated and the gas companies don't help , why hell... they want YOU to waste money.