98 vs 95 E5

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CharlieVictor
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98 vs 95 E5

Postby CharlieVictor » Mon Apr 15, 2019 8:22 pm

I have read a few times that 98 octane rated (we call it SP98 in France, for "super 98") is not recommended for our old steeds, twin shocks airheads.
Yet 95 octane gasoline is now available with at best 5% ethanol (E5), and more and more frequently E10...

What's your take on this?
Am I better off for my R100S with the highest octane rating I can get, or with a lower octane rating with a bit of ethanol?
1978 BMW R100S "Naked"
1999 W650 RS "Twin with a kick"

Mjolinor
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Re: 98 vs 95 E5

Postby Mjolinor » Mon Apr 15, 2019 9:20 pm

Do you think that the higher octane has no Ethanol in?

Petrol companies are not obliged to state Ethanol content on fuel that is over 95 octane as long as it is 5% or less.

I think that only Esso and BP will state "no ethanol" in their 97 octane and that statement seems to be somewhat blurred.

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CharlieVictor
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Re: 98 vs 95 E5

Postby CharlieVictor » Tue Apr 16, 2019 6:58 am

So what you saying is, 95 will do fine?
1978 BMW R100S "Naked"
1999 W650 RS "Twin with a kick"

Mjolinor
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Re: 98 vs 95 E5

Postby Mjolinor » Tue Apr 16, 2019 7:16 am

So what you saying is, 95 will do fine?
No. I don't know. Certainly from the view of the Ethanol it makes no difference. Even if the manufacturer says E0 it can be up to E5 before they are breaking any rules.

There are other reasons for using higher octane. My last Smart car gave an increase in MPG that was greater than the price difference between the two.

It like buying a mobile phone contract, confuse and conquer.

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CharlieVictor
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Re: 98 vs 95 E5

Postby CharlieVictor » Tue Apr 16, 2019 8:19 am

Okay I see your angle.
Well I'm not concerned about fuel consumption really, not on a 5L by 100 kms bike... But the information available is somewhat confusing: Type 247 engine not designed for high grade gas, low grade gas bad for engine because of ethanol... I guess I'll have to try 95 for two or three fill-ups and see if there is any difference...
1978 BMW R100S "Naked"
1999 W650 RS "Twin with a kick"

Mjolinor
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Re: 98 vs 95 E5

Postby Mjolinor » Tue Apr 16, 2019 9:12 am

Also remember that "High Grade" back then was over 100 octane. Fuzzy memory but 5* = 102 or so maybe.

The ethanol aint really that bad apart from the bits it buggers up and those can be replaced with ethanol safe parts now anyway.

What you cannot avoid is that if you use fuel with ethanol then the carb dismantling and cleaning period is reduced by some orders of magnitude.

I haven't got to a time between cleaning but I am heading towards once a week for the float chambers off and clean them. That nasty white stuff will completely bugger your carb if you let it build up, no way back from that but a replacement carb.

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CharlieVictor
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Re: 98 vs 95 E5

Postby CharlieVictor » Tue Apr 16, 2019 9:21 am

Thanks.
1978 BMW R100S "Naked"
1999 W650 RS "Twin with a kick"


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