An old but good reminder of 2 stroke oils

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C George
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An old but good reminder of 2 stroke oils

Post by C George »

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Re: An old but good reminder of 2 stroke oils

Post by Jaguar »

this was news to me:
"When all of the two-strokes (the old days) were developed, they all used Castrol petroleum oil at a 20:1 ratio and found that 92-octane gas had the octane reduced to 72 with presence of that much oil. Modern oils won’t affect the fuel quite as much, but if you started with 86- or 87-octane regular fuel, you can see where you’ll end with a very low octane mix. "

I'd like to read something else that states that oil reduces octane.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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Re: An old but good reminder of 2 stroke oils

Post by KDXGarage »

Cool read. I have all the KDX owner / service manuals, and remember seeing one of them stating 20:1 or so. I think it was the KDX175.
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Re: An old but good reminder of 2 stroke oils

Post by C George »

Jaguar wrote:this was news to me:
"When all of the two-strokes (the old days) were developed, they all used Castrol petroleum oil at a 20:1 ratio and found that 92-octane gas had the octane reduced to 72 with presence of that much oil. Modern oils won’t affect the fuel quite as much, but if you started with 86- or 87-octane regular fuel, you can see where you’ll end with a very low octane mix. "

I'd like to read something else that states that oil reduces octane.
I've read other places where oil reduces octane but I don't recall it to be the 20 points that this person stated.
Maybe a few points.

I mixed up some premix for my chainsaw at a much higher oil content than usual and besides running like a champ , you could feel a
noticable difference in compression after restarting a few times.
05 KDX-220R / 06 KDX-225R / Maxima 927 / Millenium Tech / Ron Black / PC , FMF / Many 220 engine mods / 40 + yrs. of riding dirt bikes 🤟🤟
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C George
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An old but good reminder of 2 stroke oils

Post by C George »

A little more info on oil affecting octane.

http://corboatracing.com/octane-two-str ... y-outboard
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An old but good reminder of 2 stroke oils

Post by ohgood »

oil reduces octane ? hmm, that's weird, i would have thought it was exactly the opposite, since most of the modern oils have very high flashpoints. they're meant to lubricate, not to burn.


hmmm
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Re: An old but good reminder of 2 stroke oils

Post by shoe757 »

So if I switch from 40:1 to 1:40 I should gain at LEAST 12 HP from better ring seal right? Kidding of course :partyman:

Good read for first time 2 strokers! I've met a lot off people that adjust fuel mix to "lean" or "richer" the bike
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Re: An old but good reminder of 2 stroke oils

Post by Jaguar »

Petroleum oil burns along with gas whereas synthetic does not. So maybe that is why they say that "modern oils" (ie: fully or partially synthetic) don't affect the octane much.
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Re: An old but good reminder of 2 stroke oils

Post by C George »

Jaguar wrote:Petroleum oil burns along with gas whereas synthetic does not. So maybe that is why they say that "modern oils" (ie: fully or partially synthetic) don't affect the octane much.
That makes sense to me
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