Should You Run Premium Gas In Your Motorcycle Octane Explained The Shop Manual
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00:00When you pull up to a gas station you've got three choices for fuel. You can get
00:04regular, mid-grade, or premium. Which should you choose and does it make a
00:09difference? Today on RevZilla we'll explain octane ratings and what they
00:13mean for your motorcycle. Let's open up the shop manual. Your standard North
00:21American gas station offers three grades of fuel. You've got your regular which is
00:26usually labeled an 87 octane. You've got your mid-grade which is typically an
00:2989. And then you've got your premium which is often a 91 or a 93 octane fuel.
00:34Oh that's the good stuff. Now European gas stations typically display higher
00:41numbers but that's only because they use a different rating system. The grades are
00:45actually equivalent. And when it comes to fuel grade and octane in particular a
00:49lot of people think it's an indication of the gasoline's power density. And then a
00:53higher octane gas will net more horsepower, get better mileage, or offer
00:57better throttle response. Not quite. I mean it's an easy connection to make
01:02given all the high octane cafes, high octane CrossFit gyms, and other brands
01:06and products that use the high octane label to convey potency. But high octane
01:11gas alone does not yield more power unless it's preventing detonation which
01:16is also known as engine pinging or knock. The higher the octane the more
01:20resistant the fuel is to detonation. To understand what detonation is and why
01:25you'd want to avoid it let's talk about the combustion process for a moment.
01:28Under normal conditions the spark plug ignites the fuel mixture and the flame
01:32front spreads evenly throughout the combustion chamber. At 5,000 rpm this
01:36happens 40 times per second. In a detonation situation there's spontaneous
01:41ignition somewhere in the combustion chamber after the plug fires. It's a
01:45renegade flame front and it's bad news. When the two flame fronts collide there's
01:49a massive pressure spike in the cylinder that presents itself as a
01:52pinging or knocking noise. The detonation shockwave hammers on the piston and can
01:58crack the piston crown, deform ring lands, collapse rod bearings, and cause all
02:02kinds of other damage. Detonation is more likely to occur when the fuel air
02:07mixture is squeezed harder which is exactly what performance engines with
02:11their high compression ratios and sky-high rev limits do. So while high
02:15octane gas and horsepower do go hand-in-hand, premium gas isn't making
02:20more power. It's simply allowing the engine to work harder without getting
02:23rattled apart by detonation. It's a little like drinking a protein shake. If
02:28you do it in conjunction with a kick-ass workout it helps you build muscle.
02:32Meanwhile drinking it without getting off the couch will fill your tank but it
02:36won't do you much good otherwise. It is delicious though. It really is. If you're
02:44wondering what octane fuel to use in your bike it'll be listed on a sticker
02:47on your gas tank or you can find it spelled out in your owner's manual. And
02:51whatever the manufacturer recommends is what you should stick with because
02:55that's what your bike was designed to burn. If you're running premium in a bike
02:59that calls for regular because you think it's going to make more power or net you
03:03more MPGs, you're wasting your money. The only reason you need to upgrade your gas
03:07is if you've installed high compression pistons or advanced your ignition timing
03:11or done some other mod that's going to increase combustion pressure and
03:14temperature. But unless your bike is knocking on 87 octane it's not gonna run
03:19any better or make any more power on 89 or 93. On the flip side if you're
03:25thinking of going cheap and putting regular in a bike designed to burn
03:28premium, well here's another look at those wrecked pistons. However if you're
03:34forced to fill up on subpar fuel for some reason don't freak out. Just avoid
03:38high load and high rpm riding until you can add an octane booster or fill up
03:42with the correct grade gas. All that being said there is more to fuel grades
03:47than just octane. As you go up in octane you also go up in additive
03:51concentration, namely detergents designed to keep your injectors, valves, and piston
03:56crowns clean. The idea here is that a vehicle engineered to run on high octane
04:00gas is likely built to a higher state of tune, so internal cleanliness is
04:04essential for proper performance. There is a concentration requirement for
04:08detergents and about 50% of retailers only put in the minimum. This is usually
04:13what you find sold at no-name discount stations and it can lead to carbon
04:16buildup on your piston crowns, your combustion chamber, and your valves, and
04:20in the long run that can impede your engines performance. Then there's top
04:25tier fuel which is what most big-name retailers carry. Top tier fuels contain a
04:30higher concentration of detergent additives, 2.5 times more at minimum
04:34across the grades, with some stations premium using seven times the required
04:38amount. So if you frequent the Kwik-E-Mart for discount regular gas, the occasional
04:43tank of premium from a name-brand top-tier station may do your engine some
04:47good. In summary, more octane does not mean more power unless your engine has
04:53been modified to take advantage of the high octane fuels anti-knock index.
04:57However, premium gas does have a higher concentration of detergents which can
05:02keep your engine cleaner which in the long run will help sustain power,
05:05mileage, and throttle response. So go ahead and fill up with premium if it
05:11makes you feel better, just don't think that it's making your bike any faster.
05:27you