I was just curious what grade of gas everyone runs in thier motrocycle.  I have always used the highest grade available, but not sure if that is necessary, or even the best for my bike...which is a Harley Softail.

Hope you guys don't think this is a dumb question.

Sorry...but what's octane booster?

Hi SweetSoftTail,

An octane booster is a product sold in most any auto parts store and it does exactly what the name says...boosts the octane in the gasoline. One of the originals and probably the most famous is STP.

Bottom line is I would run Premium gas in your bike all the time, just like it should say in your owners manual. With the mileage you get on your bike I wouldn't worry about losing a few miles per gallon, which you will since higher octane gas burns faster, hence giving you more power.  (That's where I have to disagree with highrisk's previous post - there is no way to get more power and burn less fuel.  Whoever figures that one out is a billionaire overnight).

As far as octane boosters, I really don't recommend regular use of them unless you are racing and prepared to work on your engine more often. Despite the small temporary benefit, use boosters sparingly as most rely on MMT (methylcyclopentadienyl manganese tricarbonyl) as a means of boosting the octane. Excessive MMT can cause problems with sensors, injectors, or even the exhaust, and it's bad for the environment.

Sweet, Let me try to demystify this a little for you.

Gas in your engine gets compressed first and then the spark plug sparks and the gas ignites.

Octane is the stuff in gas that resists igniting from compression.  So if an engine is higher compression, which yours is, a lower octane gas could ignite just from being compressed.  That makes the engine run rough because the gas isn't combusting at the right time.

Higher octane lets the gas fully compress so the gas gets ignited from the spark and not before.

Your engine has a 8.9:1 compression ration which is on the higher side.  HD recommends 91 octane which is exactly what you should try to get.  The only reason I mention this is because some gas stations have racing fuel at the pump which is 100-103 octane.  You don't need this and shouldn't use it.

Another thing to keep in mind is that if your traveling through higher altitudes, i.e. Colorado, the octane ratings are lower because the higher altitude lowers your compression ratio.  So if your in an area like this and the Premium gas 87-89 octane, don't worry, this is fine for the mountains.

Hope I helped.

No, it's not really common around here, but I've seen it a handful of times.  The station closest to me switched from the racing fuel to E85, so I'm not sure how common it is anymore.  I've got a hunch the racing gas isn't "green" enough.

  I have always run nothing but 90 - 92 octane in all of my Harley V-Twins and have never had any problems, performance or maintenance, and I had over 110,000 miles on my old Road King.

I agree 100% with what Frank (and a few others) said. Run what Harley-Davidson recommends for your bike which is 91 octane.

If for some reason you can't find it, a tank of slightly higher or lower octane will not hurt anything.  But don't use the additives.

Ok, I know this is a motorcycle topic, but I have to ask...Is this the same in a car. I have a Honda Accord and I thought running premium gas would be better for it  (you know us women, if it cost more it must be better). But it seems like when I run premium gas I get less gas mileage and I don't notice any increase in performance.

It's the same concept in cars.

If you have an older vehicle (car, bike or whatever) higher octane may improve performance because older engines, especially carbureted, or high mileage engines tend to have carbon buildup.  Carbon can make it run bad but higher octane can counter that effect, which would explain why Mike's 1990 runs better with Premium.

As for something newer or with less miles, there may be some improvement with higher than recommended octane but occasionally it will hurt the performance.

Think about it like this.  The manufacturer of the engine setup a specific compression ratio and they know exactly how long it takes for the different grades of gas to ignite.  So they program the spark plugs to spark at to a very specific time and recommend an octane level based on that specific timing.

Now if you use gas that is different than what they timed the engine for, it could cause the engine to run poorly, which sounds like what happened to you, Donna.

in australia we get 91 95 and 97
Mechanic told me as Viagra is only 8-1 it was a waste using high octain and definatly dont use ethonel mixed fuels

Okay, my turn. I just spent one hour reading over many different articles on octane from different sources, am disappointed that nowhere did I find using higher than recommended octane improves anything at all.

An engine only knows octane exhists when it doesn't have enough of it and spark knocks from pre-detonation. My entire adult life I have believed and felt in my soul Premium fuel is better in any engine but can't find any data to back it up with, regular fuel has all the neccessary additives to keep your engine clean and running efficient.

All these years and different vehicles from chain saws to motorcycles I have used premium fuel, the last van I bought new in 1988 used premium for 110000 miles, I felt guilty one day and spent a couple hundred bucks on ignition componants, took the original spark plugs out and was shocked, they looked excellent and didn't feel any difference after replacing them. I haven't had to change a sparkplug in anything I bought new the past twenty or thirty years, can let a generator sit with premium for four or five months and start the 2nd or 3rd pull but I found no data saying premium lasts longer in storage.

I did find one interesting fact about ethenal, it burns hotter, not real good for Air Cooled Engines and it evaporates rather fast, not good for storage.

Regardless of everything I have read today I will still use premium in all my engines till the day I die.........

Short note: E85 is an alcohol mixed fuel which degrades quickly, will deteriorate some parts made of plastic or rubber, burns slower and will absorb water. Water in the fuel will cause rust in the tank if not coated and will corrode brass and aluminum. Newer fuel injected, electronic ignition engines will try to compensate for fuel burn rates and air fuel mix ratios but only E85 prepared engines really do well. Non E85 engines especially older ones may even stop. The 90/10 mixes most commonly found will run and burn fairly well but when comes to winter storage it is best to fill and add preservative. It also absorbs water but sealed full gas tanks do better. Also Fuel injection cars and bikes with fuel pumps in the tank use the fuel to cool the high pressure pumps for the injectors. It is best to keep the pump cool with a full tank. Try to stay above 1/4 at the lowest. When the pump heat up the pump parts get hot and wear quickly and insullation of the motor windings start to break down. Save the pump replacement cost and keep it cool with fuel.

Oh, I miss the days of Ethyl.

they can't take away yer freedom g...but they can take yer bbq tank...

I use the Shell hi-test all the time (as long as I can find it) that Nitrogen additive...dunno if it is worth a crap or not, but since the old Sunoco 260 is not around anymore (just kidding) I try to use the best stuff I can find - short of AvGas

I usually don't pay that much attention to brand, just make sure that I always get 92 octane

I profile gas stations, if they look like crap the gas is probably crap too.

I use 87 Octane, thats what is suggested by the manufacturer

Check out yer HD manual for your year of bike - the min Octane recommended is 87 - but I only 92 or 93 octane in mine. If your on a road trip and 87 is all you can find then it won't hurt to use it but I would be looking for 93 for the next tank.
Another advantge of using hi-octane is it burns cleaner and doesn't leave carbon build up on the valves and heads; the reason for this complete burning of the fuel.

Shells premium V-pro, even found it w/out ethanol.

Most pumps in Mn have 91-93 octane nonoxygenated(no ethanol) for "collector cars small engines, motorcycles, etc".It's what I use in everything but my car and pickup.

The manual for my '03 Dyna (twin cam 88) says to use a minimum of 91 octane, I wouldnt use anything less than that unless your manual states otherwise.