New Moto Guzzi Door Mats Available Now
When I first had my 2007 Road King, I bought gas wherever I happened to be at the time I needed it, paying no attention to brand. And sometimes its idle was crappy and sometimes good. When I would perform each service (at 5K mile intervals), the inside of the throttle body was filthy black.As I became aware of Top Tier gas (probably the bike had 25K miles or so), I started using it exclusively. Idle quality improved dramatically, and the inside of the throttle body was now nearly clean when I did each service. That part clearly is not imagination. Bike now has 48K.
I wonder how the quality of fuel that never gets sprayed in a throttle body keeps it clean? Especially when the primary reason for Harley throttle bodies to gum up are the head breathers vented to the body.Your 07 didn't have an EVAP system did it? I had one of the first EFI Harleys back in 96 (EVO RK with Weber-Marelli EFI) and I had to manually clean the throttle body every 10k or so no matter what fuel I used.
I have a 1967 Alfa Romeo. I bring this up because it knocks on anything other than Exxon, Shell, BP. Even Sunoco causes it problems. It was designed for lead and higher octane ratings than anything we have today, so this is what I do. If I want to know if a gas is any good. I take the Alfa down and filler her up, always with Super. This is what I have discovered doing this. Some gas is better than others. The three I listed above work well in the car, but what is more interesting are the lower name brands like Liberty and stuff like that. The car can't run on them without significant overheating, and I think it is this. Ethanol gas has a short shelf life from manufacture to use. I believe that the lower brands are created to help dispose of gas that is reaching its expiration date and started absorbing a fair amount of water and otherwise breaking down.
No EVAP on mine (Pennsylvania). Now I have no idea why the TB used to be filthy on both sides of the butterfly, but no longer is . . . always have used the stock HD air filter and washed it at 5K intervals, and the bike is 100% stock mechanically.
I wonder how the quality of fuel that never gets sprayed in a throttle body keeps it clean? Especially when the primary reason for Harley throttle bodies to gum up are the head breathers vented to the body.
Kev, my theory is that although the fuel might not get sprayed in there, because of the valve overlap a small amount of fuel and engine afterburn will get blown back up the induction tract. This gives rise to the black deposits that some are reporting.
I'm not going to pretend I have the answers. But I have some ideas and maybe those smarter than me about fuels can chime in and help clarify.So we know this about fuels, octane equals stability or a resistance to burning.So If your Alfa knocks on the others, there's something about the one (could be as simple as actual octane or some other factor that is effecting stability) that helps it run right for the Alfa.But of course, that doesn't mean the same fuel is "better" for anything else right?Now the overheating part is funny. It can't be water. Water doesn't help combustion, so it's not going to create additional heat in the combustion chamber right. But ironically Ethanol is an oxygenate. It makes the air/fuel ratio less rich/more lean, and more lean = hotter. So could it simply be a higher content of Ethanol (don't most pumps say language like MAY CONTAIN UP TO 10% Ethanol or the like)? Ethanol should be cheaper, since it's got less bang for the buck, so a higher percentage might mean cheaper right? Just thinking out loud.Again though, none of this might mean anything to a motor that runs just fine on it, except maybe lower efficiency/fewer mpg.I was in PA too, till 2 years ago, so ok. Sure would like to hear a reasonable explanation of that one. Though just the fact that you can wash the OEM element and don't replace it from oil fouling means your breathers really aren't carrying too much oil mist into that throttle body anymore. Why that would change with fuel boggles my mind. But I'd sure like to know how to have that happen on mine lol.
I use the Alfa as my test bed because it is operating on the edge of what modern fuels can deliver. My father's Cadillac CTS with direct injection can run on anything because it is direct injected. All machines will use fuel differently depending on their design. The question here is whether some gas is better than others, and I have to say unequivocally that yes some fuel is more stable delivered at the pump, whether that is because of different formulation or post manufacture delivery whose to say. I do also know this. Ethanol fuel is less stable than older formulations with Lead or MTBE as anti-knock compounds. As it breaks down, absorbs water, it lowers its octane leading to knocking. It is the knocking that causes overheating because what is knocking? It is preignition of the fuel so instead of a bang when the spark plug goes off there is this inefficient burn that translates the chemical energy of the fuel to air mixture not into motive force but heat energy. That is why the engine heats up on bad gas, you get less gas mileage, less power ... all that jazz. Now what is good to use in your motorcycle? Personally I believe that if the bike is injected, then it is hard to screw up as long as you stick with the octane rating, which means staying away from off brand providers because I really don't believe that those companies are reliably providing the octane that is on the sticker by the pump handle. I have no data to support that. It is just my personal opinion.
Too high an octane means increased deposits and emissions.