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What phenomenon could make that happen? Why would premium gas actually decrease your mileage?
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Mar 12, 2012 19:00
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Sagebrush posted:What phenomenon could make that happen? Why would premium gas actually decrease your mileage? Premium gas has less BTU's than regular gas. You always want to use the lowest reccomended octane level that's safe for your engine. The reason it has less BTU's is so that it doesn't detonate under higher compression.
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Mar 12, 2012 19:04
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Sagebrush posted:What phenomenon could make that happen? Why would premium gas actually decrease your mileage? Because premium gas is more detonation resistant. Lower octane means that your gas detonates at lower compression. Edit: What Mr. Zig says.
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Mar 12, 2012 19:26
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MrZig posted:Premium gas has less BTU's than regular gas. You always want to use the lowest reccomended octane level that's safe for your engine. The reason it has less BTU's is so that it doesn't detonate under higher compression. Huh, I had no idea that there was actually less energy per volume in premium gas. Weird. How far does that trend continue? Diesel fuel, for instance, would have an "octane rating" of like 500 since it doesn't detonate at all in a gas engine, but the fuel itself has a higher energy density than gasoline.
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Mar 12, 2012 19:30
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Seems like you'd want diesel to detonate at fairly low pressures, you're not hitting the detonation point by pressure in gas engines (at least I don't think you are...)
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Mar 12, 2012 19:42
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Sagebrush posted:Huh, I had no idea that there was actually less energy per volume in premium gas. There isn't. Octane rating doesn't relate to energy content of the fuel. It's a measurement of the tendency to burn controlled (no detonation).
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Mar 12, 2012 19:44
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Sir Cornelius posted:There isn't. Octane rating doesn't relate to energy content of the fuel. It's a measurement of the tendency to burn controlled (no detonation). MrZig just said "Premium gas has less BTU's than regular gas." and you agreed with him -- if that's not true then what is actually happening? I understand that the octane rating is a measure of resistance to detonation, but I thought that was the ONLY difference (besides detergents, etc) between premium and regular. The two of you seem to be suggesting that fuel that ignites more easily produces more energy. That doesn't seem accurate because the octane rating, at least when you're dealing with actual isooctane, refers just to how extensively branched the hydrocarbon is -- all of the bonds are still single bonds so you're going to get the same energy from combustion regardless of the isomer. But I am willing to accept that there's something else at work that I don't get. My understanding is that if you put high octane gas in a low compression engine, it doesn't detonate, the spark still ignites it at the proper time, the compression ratio is the same regardless, and the burning fuel produces the same amount of energy as an equal amount of low-octane gas. So you have the same amount of power as if you used regular, but with more "headroom" to avoid detonation as it were. Which is why I can't figure out how an engine would run worse on premium than on regular. 
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Mar 12, 2012 20:09
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Bixington posted:Seems like you'd want diesel to detonate at fairly low pressures, you're not hitting the detonation point by pressure in gas engines (at least I don't think you are...) Diesels have compression ratios like 16-23:1 on average, so it takes quite a bit.
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Mar 12, 2012 20:24
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The internet says diesel has an RON of ~20 My logic was probably all wrong for assuming it being low though. 
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Mar 12, 2012 20:46
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Sagebrush posted:Simple explaination: They both have essentially the same amount of energy, but they burn differently. If you use lower octane fuel in a high compression 'performance' engine; The engine will be timed to ignite the fuel earlier, expecting a cooler, longer burn. The low octane fuel will burn way too quick or 'detonate' before the piston is in the right position and cause damage to the engine. High octane burns cooler and slower than low octane so if your engine is timed/tuned for low octane fuel and you run high octane fuel, it will not be timed right to get all the energy it could out of the fuel. The fuel will be still burning after it has passed th point in the engine stroke where it would produce the best power.
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Mar 12, 2012 20:48
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Ah, that makes a lot of sense, then. I wasn't aware that the octane rating affects the burn rate as well as the point of ignition. So theoretically if you advanced the ignition timing (and messed with the intake and exhaust too, I guess) you could get just as much power running premium in your low-comp engine as you would with regular? Also, shouldn't this mean that premium gas is actually worse in high-revving engines, because the slower burn means that the engine loses efficiency sooner?
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Mar 12, 2012 20:58
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Sagebrush posted:Ah, that makes a lot of sense, then. I wasn't aware that the octane rating affects the burn rate as well as the point of ignition. So theoretically if you advanced the ignition timing (and messed with the intake and exhaust too, I guess) you could get just as much power running premium in your low-comp engine as you would with regular? Let me blow your mind and tell you that there's no significant difference in the speed of the flame front travel between high and low octane fuel. If you really want to understand this, focus on compression ratio and ignition timing. Think of it as how much compression the air/fuel mixture can manage before it detonates rather than burns/combusts when ignited.
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Mar 12, 2012 21:46
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Manual for my bike says 91 RON, I used 98 RON for a while before trying out 91 RON. Both had the same mileage/litre so I was just wasting my money. 
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Mar 12, 2012 21:48
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Odette posted:Manual for my bike says 91 RON, I used 98 RON for a while before trying out 91 RON. If you do this for fun and giggles, I'd recommend that you go a grade hotter in sparkplugs and advance your ignition timing a bit for 98 RON. But yeah, you wasted your money.
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Mar 12, 2012 22:07
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Sir Cornelius posted:Let me blow your mind and tell you that there's no significant difference in the speed of the flame front travel between high and low octane fuel. If you really want to understand this, focus on compression ratio and ignition timing. Think of it as how much compression the air/fuel mixture can manage before it detonates rather than burns/combusts when ignited. You're contradicting what the other people are saying. I totally understand (and have said this a few times) that high octane fuel can withstand more compression than low-octane and so that allows you to use engines with higher compression ratios. Remember that these aren't diesels though! If the engine is working properly, the fuel should never ignite under compression, only when the spark fires. ReelBigLizard says that high-octane fuel burns more slowly as well as being more resistant to detonation, which is why an engine timed for regular can't extract as much energy from premium. But you say the flame front travels exactly as fast and produces exactly as much energy whether you use premium or regular. Assuming the mixture isn't pre-igniting, the compression ratio is the same, the ignition timing is the same, the fuel energy is the same, the flame propagation speed is the same. Yet clutchpuck claims that using premium made his engine run worse and decreased his fuel economy. What is going on?
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Mar 12, 2012 22:18
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Sagebrush posted:What is going on? People are ignoring the fact that they are sitting at the best research tool ever devised and insist on using incorrect lines of logic to argue on an online comedy forum without actually looking anything up first.
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Mar 12, 2012 22:35
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Sagebrush posted:ReelBigLizard says that high-octane fuel burns more slowly as well as being more resistant to detonation. ReelBigLizard is kind of wrong then. High octane fuel combusts almost as fast as low octane. High octane can be compressed more before ignition and wont detonate instead of combust. Lower octane fuel would detonate given same environment. Does that explain it?
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Mar 12, 2012 22:41
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Sagebrush posted:You're contradicting what the other people are saying. I totally understand (and have said this a few times) that high octane fuel can withstand more compression than low-octane and so that allows you to use engines with higher compression ratios. Remember that these aren't diesels though! If the engine is working properly, the fuel should never ignite under compression, only when the spark fires. The difference in flame speed, even a barely-appreciable one, adds up when you're igniting it x degrees later than optimal, 4000 times a minute. Running conditions (compression and heat) affect the octane requirements, which along with RPM (the faster its running the more advance it needs) affect the optimal spark advance. The vstar is a low-revving engine with low octane requirements, so it's going to have pretty drat relaxed timing to begin with. That's a real good combination for wasting energy straight out of the exhaust port.
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Mar 12, 2012 22:48
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Sir Cornelius posted:ReelBigLizard is kind of wrong then. High octane fuel combusts almost as fast as low octane. High octane can be compressed more before ignition and and wont detonate instead of combust. Lower octane fuel would detonate given same environment. Does that explain it? No, because the situation we're discussing is a constant engine that compresses the fuel a constant amount and doesn't detonate in either circumstance. Yet it runs worse with high-octane fuel. I'm crystal clear on the differences where you can alter the ignition timing and compression ratio to take advantage of the increased resistance to detonation, but I still can't figure out why premium would run worse in a given engine than regular. In ANY engine. At this point I'm tempted to just say "eh, clutchpuck probably perceived an effect that wasn't actually there" and drop it cause I think I'm just confusing myself more and this is certainly a huge derail. CONTENT Today I scrubbed enormous amounts of dirt and grease out of the clutch actuator and cleaned the parts themselves in paint thinner. Need to buy another tube of bearing grease and I can put it back together. I'm also halfway through what looks to be about a five-day process of electrolytically dissolving a damaged steel bolt out of an aluminum housing. It's working, but by god is it slow.
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Mar 12, 2012 22:48
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I immediately noticed less decel popping when I switched to lower octane, that was my yardstick on "better". I suspect if the O2 sensor was getting confused by incomplete combustion, it may have been leaning it out some, enough to heat the exhaust up. I dunno. All I know is less annoying pop. On the butt-dyno it was pretty much the same either way. Practical difference was in the fuel economy.
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Mar 12, 2012 22:56
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Sagebrush posted:Today I scrubbed enormous amounts of dirt and grease out of the clutch actuator and cleaned the parts themselves in paint thinner. That explains it  Sagebrush posted:the fuel should never ignite under compression, only when the spark fires. I'm the one that's confused now. We didn't talk diesels, did we? Sir Cornelius fucked around with this message at 23:04 on Mar 12, 2012 |
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Mar 12, 2012 22:59
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^^^ just drop it, man, it's starting agaaaaaaaainnnnnn You mean the confusion? Yeah, probably. Move from xylene to hexane with plenty of acids in between. I've got so many different chemicals working for me on this project that if I had a thread I would subtitle it "better motorcycling through chemistry". Paint thinner does an excellent job of dissolving grease, though. Then hit it with regular dishsoap to clean off the scum and you're golden. Sagebrush fucked around with this message at 23:06 on Mar 12, 2012 |
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Mar 12, 2012 23:03
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Sagebrush posted:Paint thinner does an excellent job of dissolving grease, though. Then hit it with regular dishsoap to clean off the scum and you're golden. Your brain is mostly fat and grease. Please take care. I've had some close relatives that didn't, and the result weren't appealing.
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Mar 12, 2012 23:08
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Is there any reason to bump up a fuel grade with a jet kit and pipe? My pops has a FZ1 he bought that way that's been running like rear end and he insists on putting Premium into anything, and I was wondering if that could be making it worse? He says that the kit is part of the reason he puts in premium. Of course, he insists on using premium in my bike as well (not gonna turn down a free tank when riding with dad) that is bone stock, runs fine on regular, and has a manual that calls for regular. I think pretty much every mod the PO did on the bike is awful except for the Corbin seat but it's hard to tell him that. He took it to a guy who builds race bikes to check it out and the guy told him to get rid of the jet kit and can, lol. He disagrees of course. For some on topic, a day late but I went out for my first proper cruise with the bike set up naked and with all the doohickies I added to it over the winter. Did some gopro video and some time lapse shots, pretty nice. 
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Mar 12, 2012 23:35
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A jet kit for just a can seems inappropriate. Full open intake and exhaust system without a catalyzer, I can see it, but with just a can and a jet kit he's probably running pretty drat rich.
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Mar 12, 2012 23:43
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clutchpuck posted:All I know is less annoying pop. Popping is one of the small pleasures in life... Really brightens my commute anyway.
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Mar 13, 2012 00:19
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The fuel will be making no difference, it's likely it's just not jetted very well. You don't need to swap to high octane until you start messing with things like head work, upping the compression, bore-up kits and modifying the ignition curve. My explanation was extremely basic, and not really the full story which is why I prefaced it with 'Simple'. There are a bunch of variables involved from ignition advance to spark 'heat' and compression, I've found it's just easier to explain it that way. Petrol (or Gasoline as many of you colonials seem to call it) is a cocktail of various distillates and additives, likely none of which - even more confusingly, are actually real Octane (maybe in trace amounts). "Octane" rating is actually a rating comparing a fuel to a known fuel - iso-octane. This is confusing because actual Octane, which is very different to iso-octane, if added to fuel, would make pre-detonation worse. A rating of 100 means that the fuel mix you have, regardless of what it contains, has something like the same pre-detonation characteristics "knock resistance" as straight iso-octane; they might have achieved this by adding iso-octane, they might not. This is how you can get fuel that is actually better than 100. If fuel just had a number, and it wasn't called things like Super (here in the UK) or 'Premium', then it probably wouldn't be such a debated issue. It's in the Petro-companies interest to sell the expensive stuff though, I doubt high octane really costs much if anything more to produce. The long and short of it is: If your manual says use super/premium, or your engine is modified for more compression/advance use it. An engine hosed by pre-detonation is a cost way more hard to swallow than a few pence extra at the pump. Otherwise, use regular. For an engine designed for regular there's no benefit to using super, and the only harm it will do is to your wallet. ReelBigLizard fucked around with this message at 00:23 on Mar 13, 2012 |
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Mar 13, 2012 00:21
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Piston after knocking like a pro.
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Mar 13, 2012 00:46
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ReelBigLizard posted:If fuel just had a number, and it wasn't called things like Super (here in the UK) or 'Premium', then it probably wouldn't be such a debated issue. It's in the Petro-companies interest to sell the expensive stuff though, I doubt high octane really costs much if anything more to produce. I always figured it was supply and demand. Less people use high octane gas so less is made and it costs more. Same reason straight coffee beans cost more then ground up coffee. 
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Mar 13, 2012 00:48
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My new bike has a sticker saying I should use minimum 90 octane gas. I put in some 89 this weekend. Is it going to explode? 
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Mar 13, 2012 01:34
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Yes, run away from it.
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Mar 13, 2012 02:01
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Got home from work and torqued to spec all the fasteners I've been dicking with since I owned the Ape. Going to invest in a nice torque wrench soon...these Italian fasteners feel like cheese. I feel like I could just do whatever on my Yamaha, now I accidentally don't hit a caliper bolt perfect and it gets rounded on an edge just a bit. Weak. and tires:  
Mcqueen fucked around with this message at 02:34 on Mar 13, 2012 |
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Mar 13, 2012 02:27
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I used my bike to drive over my foot just now... That hurt!
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Mar 13, 2012 02:32
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Sir Cornelius posted:If you do this for fun and giggles, I'd recommend that you go a grade hotter in sparkplugs and advance your ignition timing a bit for 98 RON. But yeah, you wasted your money. I never got a manual with the bike, and the previous owner said he ran it on 98.  Took me a while to figure out I was just pissing money away. Mcqueen posted:and tires: You ... you rode home with the tire on your backpack? I salute you, good sir.
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Mar 13, 2012 03:08
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Rode 80+ miles this weekend after previously only neighborhood and parking lot riding . It was wonderful.  Rode to harbor freight to get a heat gun and some goo gone to make short work of removing the side decals off the 250. Pulled the stock bars off the CB and test fit the Euro bars. I like em. Going to be a pain to drill the holes though.
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Mar 13, 2012 03:12
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I finally took my Naked bike on the highway for the first time. I'm still relatively new, and only took it with fairings on a small 90kmh highway before the winter where I tore off the fairing. 120kmh seems to be where the windblast picks up. As people said, you just lean into it a bit. I still felt comfy and as safe as you can feel with nothing around you. It as apparently a windy day. The one thing I need to get used to is using my mirrors on the highway. They aren't big. Bit when I lean forward, they become much less useful. My neck muscles also aren't used to that much wind so shoulder checking is pretty hilarious since my body doesn't expect the helmet turning into a sail the moment I turn it. So I need to practice making sure I can keep track of what's going on around me using my mirrors and shoulder checking more. It was fun popping my highway cherry. One of those experiences you only get once. As promised Mr. Weird. Vetter bucket and all. (Bucket may change soon, but for now, everything works a treat.)  
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Mar 13, 2012 03:27
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Odette posted:You ... you rode home with the tire on your backpack? I salute you, good sir. Hahaha, I rode 50 miles there with 2 tires on my backpack. Kriega packs own folks, I highly suggest you get one.
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Mar 13, 2012 03:56
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Mcqueen posted:Hahaha, I rode 50 miles there with 2 tires on my backpack. Kriega packs own folks, I highly suggest you get one. I usually put them on me like life ring floaties. I actually got a discount because of it the last time I had my tires changed
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Mar 13, 2012 04:18
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Ziploc posted:I finally took my Naked bike on the highway for the first time. Looks drat good! After you see a Bandit without the fairings, it makes you wonder why Suzuki ever decided to put fairings on them at all, they just look so good naked! The wind thing you'll get used to after a while. You wont even notice it once you get used to it.
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Mar 13, 2012 04:21
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Agreed for sure, coming from someone who just did the same thing to a fz6. I got used to the half faired look, but now that it's naked I love it me. Looking at old pictures looks like my bike had an ugly growth on it. You should get a few more shots of that bandit.
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Mar 13, 2012 04:32
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