• Welcome, Guest! We hope you enjoy the excellent technical knowledge, event information and discussions that the BMW MOA forum provides. Some forum content will be hidden from you if you remain logged out. If you want to view all content, please click the 'Log in' button above and enter your BMW MOA username and password.

    If you are not an MOA member, why not take the time to join the club, so you can enjoy posting on the forum, the BMW Owners News magazine, and all of the discounts and benefits the BMW MOA offers?

  • Beginning April 1st, and running through April 30th, there is a new 2024 BMW MOA Election discussion area within The Club section of the forum. Within this forum area is also a sticky post that provides the ground rules for participating in the Election forum area. Also, the candidates statements are provided. Please read before joining the conversation, because the rules are very specific to maintain civility.

    The Election forum is here: Election Forum

What grade of gasoline for my 1991 K75 RT ?

X

xcaret

New member
Here in western Canada we now have 4 grades of gas starting at 87 octane and up to 93 I think it is. The top 2 contain ethanol the attendant says. I remember reading something about ethanol being bad for EFI . I don't remember much of the article because at the time I had no idea ethanol was being added to our gas . My bike is a 1991 K75 RT .
On other bikes I remember switching from premium to regular to see if millage or anything changed ,and I didn't notice any difference .
Any advise will be appreciated .
 
Here in Georgia we have 93 octane with up to 10% ethanol. The non-ethanol premium is typically 90 octane. If I'm pretty sure I'm going to running most of the tank out and the K75 bike will not sit for a long period I just use 93. Otherwise 90 non-ethanol. Haven't had any issues. But as they say YMMV.


Sent from my iPhone using Tapatalk
 
What He Said, Mr X:

If U intend to ride your K75, then I’d say using “high-test” would be preferable for better performance & cleaner mechanicals.
If U don’t intend to go thru your tanks on some longer rides, get the non-ethanol with the highest octane.

Here in the Tenn River valley, “some” Murphy’s stations at Wal-Marts now have N.E. 93 Octane with separate Blue hoses, but some don’t... Ya just never know from one location to another (especially across state boundaries). But we tend to burn thru many tanks of petrol doing the CoddiWomple V 2.0. :buds

Use your best judgement; all will be Okay in the long run... ;)

Happy Trails whenever U can - Ciao!
HSV-Karen & HSV-Phil
USN-Ret'd —--&-— USAF-Ret’d
'09 650GS-twin —- '14 K-GT
'82 R100CS —-—— '75 R90S
’08 CRF230L —--— ’09 KLX250S
'16 R1200RS —-— ’05 Vespa 200L
 
In Canada, Shell V Power claims to have no ethanol. I was told the same about ESSO but found at least one ESSO premium grade recently which stated 10% ethanol. Rubber bits in old K Bikes tend to deteriorate with ethanol fuel. Hence I use, whenever possible, Shell V Power in Canada and attempt to find ethanol free petrol in the US, sometimes successfully, sometimes not.

I do not know about my ‘87 K100, but my ‘98 R1100RT, definitely gets better mileage with ethanol free fuel.

I have been meaning to getting around to ordering a kit from Bob’s BMW (but unfortunately I am a procrastinator) which replaces an old K’s tank rubber items with something compatible with ethanol.
 
BMW specifies 87 AKI (Octane) Regular fuel. A 10% or less mixture of Ethanol won't matter as long as the AKI rating is 87. Running a higher AKI/Octane rated fuel will *not* make your bike run better, and in fact Premium fuels (91 AKI) are not "better" because they are designed to burn slower than Regular fuels to prevent pre-ignition in very high compression engines and won't deliver as much power in a K75 - at least in theory.

If you can access non-ethanol Regular fuel then I would suggest you run it all you can for the protection of all the rubber bits in your fuel system: the mount for the fuel pump, in-tank hoses, and the external feed and return fuel injection hoses. Ethanol is very hard on rubber not designed for it, and the K100/K75 fuel systems were not designed with alcohol-resistant rubber parts.
 
GREGFEELER said:
If you can access non-ethanol Regular fuel then I would suggest you run it all you can for the protection of all the rubber bits in your fuel system: the mount for the fuel pump, in-tank hoses, and the external feed and return fuel injection hoses. Ethanol is very hard on rubber not designed for it, and the K100/K75 fuel systems were not designed with alcohol-resistant rubber parts.
Click to expand...

However, after market replacement fuel pump mounting dampers which are alcohol fuel resistant may be bought from Euromotoelectrics and Bob's BMW - and probably others.
 
Last edited:
GREGFEELER said:
BMW specifies 87 AKI (Octane) Regular fuel. A 10% or less mixture of Ethanol won't matter as long as the AKI rating is 87. Running a higher AKI/Octane rated fuel will *not* make your bike run better...
Click to expand...

For some reason I had it stuck in my mind the K75 has a higher compression ratio than it does. You are correct it there is no reason to run higher octane fuel than the specified octane level unless the premium is ethanol free ( Shell V-Power assuming it really is ethanol free) and the regular isn't. Even then it's your choice.


Sent from my iPhone using Tapatalk
 
PGlaves said:
However, after mraket replacement fuel pump mounting dampers which are alcohol fuel resistant may be bought from Euromotoelectrics and Bob's BMW - and probably others.
Click to expand...

Good point, and one I'm going to take advantage of as part of my fall maintenance of my fleet of K-bikes. :laugh
 
Paul,

Did you forget about the S you have stashed at your son’s house in Kansas?





:dance:dance:dance
 
You must log in or register to reply here.

Similar threads

J
Ethanol free gasoline
Replies
17
Views
2K
fmdualexhaust
fmdualexhaust
X
MY 1991 k75 RT sputtered and died .
Replies
5
Views
774
xcaret
X
X
price of a 1991 K75 RT when new ??
Replies
15
Views
2K
gregfeeler
gregfeeler
dfisher1
2023 F750GS issues
Replies
8
Views
3K
stormbringer
S
X
'91 K75RT where to hook my battery tender to ?
2
Replies
20
Views
3K
xcaret
X
Back
Top