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Post by Deleted on Jul 9, 2013 21:19:30 GMT -5
I recently put in a new plug in a stock 50 cc scooter. The old plug was a light brown and had perfect AF ratio. After running  octane for 2 tank fulls the plug looked rich, having some black on the thread top. The old plug was run on mid grade  . This reminded me of a car i had back in 2000. My new mustang had issues because i was running premium fuel in my V6 and the unburned fuel was blackening my o2 sensors. The same thing happened with the scooter plug. I wonder how many of you guys are chasing a rich condition which doesnt exist thats only a result of using the wrong gas? |
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Post by scootnwinn on Jul 9, 2013 21:22:50 GMT -5
I wonder too. The high octane I think is rarely needed. My Vespa runs much better on the cheap stuff
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Post by prodigit on Jul 9, 2013 21:37:17 GMT -5
I know that BP Premium gasoline has a product in that allows my bike to have 10% better performance. Some guy called it 'paint thinner', or if not that, some kind of substance that cleans the engine that also burns better than fuel.
I also know that using that fuel on scoots running lean, could give them a performance edge; I guess because the product is more flammable (and more expensive too) than fuel, that the perfect AF ratio will change too.
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Post by scootnwinn on Jul 9, 2013 21:44:46 GMT -5
High octane fuels are less flammable period. The higher octane indicates the fuels resistance to detonation not it's propensity for it.
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Post by CopperDeer on Jul 10, 2013 0:06:52 GMT -5
Haha yall two are so cute. But yeah, he is right, higher octane indicates a higher resistance to detonation and I believe might have something to do with combustion temp as well. That's why you want it for high compression / boost, to prevent pre-detonation. It usually is formulated no different as far as actual "combustability"? I've experimented some with toluene (a kind of / component in some paint thinners) in high performance cars, when I used to be into that sort of thing... I was under the impression it's just an octane booster not rocket fuel where a drop of it equals an ounce of gasoline. It can play a factor into A/F b/c too high an octane for the particular engine results in unburnt fuel it doesn't have enough compression to combust.
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Post by CopperDeer on Jul 10, 2013 0:10:07 GMT -5
So I suppose that's why the Tao Tao's, for example, love higher octane. The one I had at least had pretty high compression and was tuned lean, so it was perfect for it. In fact 87 would have probably destroyed the motor before too long.
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Post by prodigit on Jul 10, 2013 0:46:07 GMT -5
Scootnwinn, 1- You can say the same thing in a nice way. and I like you to respect your fellow people on this site! 2- I'm addressing the substance they put into BP Premium fuel, which is not related to gasoline's octane values. They only put it in their premium fuels, and it IS more flammable. If you're unsure of what you're reading, then you can always ask, but that attitude from you towards forum members needs to change! CopperDeer: On my ATM50 it makes very little difference to choose between regular, mid grade, or premium fuel. BP Premium is about the only one that has a higher energy ratio than the other fuels. I suppose there's more to their fuel than just higher octane. |
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Post by JR on Jul 10, 2013 1:31:33 GMT -5
Taking issue in public is not acceptable. Expressing an opinion is OK, people can have wrong opinions. Keep the personal feelings about other members out of it.
Higher octane fuels do take more to burn, that is why they do not ping (pre-ignition noises) and why it can leave carbon on a spark plug, unburned fuel carbon. Yeah they do put cleaners in the fuel I have no idea what the characteristics of them are, if they burn hotter at a higher compression or what.
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Post by scootnwinn on Jul 10, 2013 1:39:15 GMT -5
Is that better fixed the post at issue
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Post by Deleted on Jul 10, 2013 2:12:14 GMT -5
So back to the question...members who are chopping plugs thinking they are rich when in reality if they used the lower rating would not be chasing a demon that doesnt exist. How many use it just because they think its proper? 10.5:1 is not worthy of premium fuel and thats what I have in my motor.
Theres no BPs here where i live and for good reason. If there were we'd probably see how well that fuel burns right at the station level after what they did to this region. In any event I have conclusive proof that if you are running normal (good plug reading) at a certain grade of gas and you then switch to a higher octane and you see a change in your plugs color, the added octane isnt needed for your engine.
My guess why people seem to get a higher top end is a result of the lower engine temps and a cooler engine may allow a higher topend but the performance getting there from 0-? is impacted and slightly slower. Almost like using a size heavier variator weight.
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Post by pmatulew on Jul 10, 2013 5:12:21 GMT -5
On a related subject: Most fuel around here is listed to contain at least 10% ethanol. So it surprised me the other day to see a sign that stated that "Brand X" premium fuel did not contain any ethanol. Since alcohol has less energy per volume than gasoline I would think that adding or subtracting that 10% of the recipe would make a significant change in how the engine behaves.
Does anyone have a feel for other brands and grades that do or do not contain alcohol? And how your results varied?
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Post by prodigit on Jul 10, 2013 5:20:50 GMT -5
I've met a few fuel pumps of unknown brand that also seemed to have a 10% better performance, much like BP Premium gasoline. But most use about the same mixture.
I find Chevron is the worst offender, it's fuel holds A LOT less energy per gallon than any other brand. Shell is slightly better than Mobil. Citgo I tried once, I think it's between Mobil and Chevron.
Those are my experiences with their gasoline in South Florida. That being said, fuel composure changes with the seasons, and sometimes from week to week (depends on the temperature too). So it's very hard to track which one is better.
On average BP has the best value, and it's not only in Florida, but in Belgium too. So I suspect it's more like worldwide.
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Post by millsc on Jul 10, 2013 8:50:02 GMT -5
I don't read the plugs anymore i can tell by the way it runs sounds and smells if its rich or lean
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Post by Deleted on Jul 10, 2013 8:59:08 GMT -5
non ethenol is what I run and seems perfect. |
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Post by jerseyboy on Jul 10, 2013 11:18:40 GMT -5
[replyingto=scootnwinn]scootnwinn[/replyingto]Yeah,,you better pipe down around here!!!  Also millsc is right,,sound,smell,how it runs will tell you everything you need to know,,but you need to know how its supposed to sound,smell,and run first  |
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octane for 2 tank fulls the plug looked rich, having some black on the thread top. The old plug was run on mid grade 
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