Let's spend a little energy thinking about a necessity that we all use but sometimes don't put much thought into: Fuel, Gasoline, Petrol. The octane cocktail made from dead dinosaurs that keeps that motorcycle of yours running in peak form. I don't think that Rumble Magazine is the forum to get involved in an editorial debate over Middle-East politics, or crude oil economic fluctuations that affect all our pocket books, BUT how about some down-home information that might help you save a some hassles; keep your machine running in top form and maybe a buck or two on repairs.
There's a ton of choices when it comes to what you pour into that exotic painted gas can that sits between your legs while you're riding, and even a few decisions that you can make to avoid some costly repairs that will leave you feeling 'fuelish' when you aren't riding.
Webster says that Gasoline is a 'Volatile, Highly inflammable (why does he have to put the "in" before flammable?), odorless liquid produced by the fractional distillation of petroleum and used chiefly as a fuel in internal combustion engines". Great. Now we all know how dangerous gas is, right? Then why is it that every year we hear about some goof-ball blowing up his house when he's pouring gas in his bike in the garage near the water-heater? Please, you've been warned, AGAIN. Use proper ventilation when handing fuel.
Now on to a more interesting topic: Octane. Octane ratings measure a gasoline's ability to resist engine knock, a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture. Most gas stations offer three octane grades; Regular (usually 87 octane), Mid-grade (usually 89 Octane) and Premium (usually 92 or 93 octane). The octane rating is posted on a bright yellow sticker at the pump. Just because it says 'Super Yahoo' grade on the pump, it does not mean that it's a high-octane quality fuel. Read the yellow FEDERAL sticker so you get the right grade of gas and not just high-level marketing.
Premature ignition sounds like a personal problem, but that's when the fuel explodes in your cylinder too far before the piston is on the down stroke. This is sometimes referred to as 'dieseling'. Because diesel vehicles don't use spark plugs, they use a less refined grade of fuel, and ignite it by compressing it in the cylinder until it explodes. No spark plugs are needed for a diesel motor, just a bunch of compression and lower octane fuel. That's great for your truck, but not too cool on your motorcycle. Modern motorcycles use sparkplugs and computerized ignition systems, which 'time' a spark to ignite the fuel at the optimum moment. When your motor is properly timed, the spark ignites the fuel when the piston is at the best part of the piston stroke, where the air-fuel mixture is at its maximum compression and ready to transfer that explosion of power to your flywheels on the down stroke. If you use a lower octane fuel, or have a very high compression motor (over 10:1) that pinging sound you hear is the fuel igniting before the optimum time. Kind of like a Diesel motor. This causes the motor to fight itself, and results in poor performance, and ultimately engine damage. Not good. The higher the octane rating, the less chance you have of pinging if your bike is tuned and ridden properly.
Another cause of pinging is 'Lugging' your motor. This usually happens when you have your bike in too high of a gear with too much of a load, especially when climbing a hill. You'll hear the sound of a bunch of marbles rattling in your motor, and like a true jack-ass, you just keep the throttle twisted wide open and the sound won't go away. Here's a clue, words to live by, or maybe you could use that sound as a 'hint' to do something different: Downshift into a lower gear. When you downshift, you are putting less strain on your engine allowing it to rev higher to create power more efficiently to climb that hill.
If you want to maximize the power output of your motor, some gear-heads will install high compression pistons, or modify and shave the cylinder heads to increase the compression ratio. This is done by decreasing the area or volume in your cylinders when the piston is at the top of the stroke. The more you compress the fuel and air before you burn it with the spark, the more power your fuel will create when it explodes, if timed properly. Yep, that means that you have a much higher chance of dieseling or pinging your motor if you have upped the compression ratio and run standard pump gas. It's a vicious circle. Once you've opted for a higher compression motor, you've made the commitment to purchase higher-octane gas or your bike will run like crap and could also overheat. Racing gas with octane ratings up to 112 and beyond is available, but it is not easily found 120 miles away from home when you need to fill 'er up. Plus this means that you can only run the bike on 'closed course' completion when using racing fuel. Not on the highways.
By the way, how did you get 120 miles away from home on that racing gas anyway? The down and dirty of the non-highway use racing fuel is that our fine Governor does not tax it the same way standard octane fuels are taxed. The government figures that if you're not paying the gas tax to build the roads you're driving on, you shouldn't be riding on them with racing fuel that wasn't taxed. You wouldn't do that, would you? I didn't think so.
Most of us are not concerned with MPG's when out on a motorcycle. The fuel is the cheap part of the whole entertainment program. What we are usually concerned with is the FPG's. (Fun Per Gallon). The fact of the matter is, if your bike does not ping on regular 87 octane gas, you don't need more expensive fuel. End of story. I prefer to err on the safe side and spend a few extra cents per gallon and pump 92-octane gas in my bike that has the least amount of 'additives'. Cheap gas at no-name stations might be diluted with additives, or have other contaminations in the fuel such as dust or other impurities. I avoid discount stations for fuel in my bike. Like with most things in life, you get what you pay for. But at the same time, there's no need to pay for more octane than what you need in a fuel to maximize the FPG's.
Here's another 'Fuel for Thought' that you might want to consider as a courtesy to your mechanic or service technician. The amount of fuel in your tank when you bring your bike in for work is a detail that often gets overlooked. It seems that a large percentage of bikes that we see coming into Steeds for service or custom work, arrive topped off with a full tank of gas. Please, when you take your bike to your mechanic, do yourself and your mechanic a favor, and bring it in with only a gallon or so of gas in the tank. Most maintenance services require removing the tank or cleaning the fuel valve filter, which means that we're constantly draining and handling fuel. At the same time, if you arrive on reserve gas, let us know, so when we're out on a test ride we don't end up cursing while we're pushing your bike back to the shop. Also, if you overfill your tanks, the gas may pass around the seal of your fuel cap and damage or blister your spendy custom paint job.
Which brings me to my final fuel thought. Think about 'Summer-izing' your motorcycle here in the Desert. If you aren't sure when you are going to ride your bike next because it's just too damn hot, or you're spending the next 3 weekends out on your boat, jet-skis or summer home where you don't have to roast with the rest of us here in the heat, at least think about your fuel before you escape. Don't leave a full tank of fuel in your bike that will turn into varnish during the summer while it's boiling in your hot garage at home. And if you do park your bike with fuel in the tank, spend the two bucks to buy some 'Gasoline Stabilizer' at your local hardware store and dump it in the tank.
A Fuel Stabilizer is a liquid additive poured in your tank that reduces the oxidation process and prevents varnish and gum build up in the gasoline. Stale gas can clog carb jets, fuel injectors, stick floats and make your bike hard to start or run properly. At the very least, it is always a good habit to turn off your fuel valve every time you park or store your bike, and then run your engine for a couple of minutes until all the gas has run out of your carburetor and fuel line. This is the best way to avoid spending money on rebuilding your carb or fuel injectors when you're ready to ride again. The people that didn't read this article help pay our rent in the fall when we sell a ton of carburetor rebuilds and replacement carbs because they left a full tank of gas to rot in their bikes all summer. If you made it all the way through this tech piece, I hope you can come on in and spend your hard earned money on fun stuff for your bike instead.
Keep the rubber side down.
- John at Steeds