my first bimmer...

[bilbob]

Ello all
Just taken in my first BMW, r1100s. To say it's a learning curve might be understating it....
First mistake was putting regular unleaded in it... I'm assuming (hoping?) this is causing such roughness!
Anyway, I'll have plenty of questions, including... How do you mount a phone to it? There's no spare handlebar... And when out in the sticks, and super isn't available, what do you do?add an additive? Ride very gently?
Anyway, I'll find my way around, but they'll be another flat twin buzzing around north Yorkshire this summer...

[SP250]

Other than when I was caning my 11S at the Nurburgring or on a trackday, I have used nothing else but regular unleaded 95 octane.
Yours might need the throttle bodies balanced if its really rough / vibrating.
Also if it is low mileage, or hasn't been run in properly they take 20,000 plus miles before they smooth out and stop consuming oil.

[bilbob]

Hmmm... I'm at a bit of a loss to start, as I don't know what constitutes 'rough' on one of these...i come from a triumph triple, and that's far smoother. I particularly noticed it when cruising in top, at a*fair* pace, opening the throttle wide caused all sorts of roughness....
Any advice welcome
Oh, It's done 27k...

[fontana]

Hmmm... I'm at a bit of a loss to start, as I don't know what constitutes 'rough' on one of these...i come from a triumph triple, and that's far smoother. I particularly noticed it when cruising in top, at a*fair* pace, opening the throttle wide caused all sorts of roughness....
Any advice welcome
Oh, It's done 27k...

You say your first mistake was putting regular unleaded in it.
So what made you assume that this was causing a running problem.
Did it run better with super unleaded ?
What you describe in regards to running certainly isn't my experience.
I think the advice already given is highly recommended.
In the meantime, check all the simple stuff like spark plug(s) not loose, caps and HT leads etc.
I once had what you described on an old Guzzi.
When I checked, one of the plugs had worked it's way so it was hanging on by a thread

After I screwed it back in it was fine.
BMW's are smooth for an air cooled twin.
Your issue doesn't sound right to me.

[bilbob]

Hmmm... I'm at a bit of a loss to start, as I don't know what constitutes 'rough' on one of these...i come from a triumph triple, and that's far smoother. I particularly noticed it when cruising in top, at a*fair* pace, opening the throttle wide caused all sorts of roughness....
Any advice welcome
Oh, It's done 27k...

You say your first mistake was putting regular unleaded in it.
So what made you assume that this was causing a running problem.
Did it run better with super unleaded ?
What you describe in regards to running certainly isn't my experience.
I think the advice already given is highly recommended.
In the meantime, check all the simple stuff like spark plug(s) not loose, caps and HT leads etc.
I once had what you described on an old Guzzi.
When I checked, one of the plugs had worked it's way so it was hanging on by a thread

After I screwed it back in it was fine.
BMW's are smooth for an air cooled twin.
Your issue doesn't sound right to me.

From memory, I seemed to recall these BM's used super unleaded, and knowing I'd just put a tankful of regular in after picking the bike up, I assumed it was that. And yes, with the super in, it was smooth*er*, not smooth...!! If these are meant to be smooth, then it definitely ain't that!
I'll do some more checks at the weekend, but I kinda hope a spark plug isn't hanging out...!
MOT is due at end of April, so I might just get the mot guys to do a balance on it at the same time.
FWIW, it's a 2001...

Cheers

[SP250]

Mine's a 2001 as well, with 33,000 on it now.

It won't be as 'smooth' as your Triumph triple, but the only vibes I get are a slight tingle at 70 ish.

Doesn't need super unleaded, although they are a bit better using it.

[Mitch1100]

Check that the little black throttle body vacumn caps aren't missing.

[dave the german]

Always used ordinary unleaded on my BCR - it was recommended to use 98 in the 12s and it did seem to make a difference although the fueling on my 12 was crap until John told me about the TPS re set!! Should be even better soon with the PC fitted!!!

[Ben]

Hi, my S has done 90k miles, always on reg unleaded without a hitch. If super is making a difference I am at a loss. The only time mine ever got any excessive vib/rough running was at about your mileage and it was the valves. Sorted them and not had to touch them since. But check the balance first.

Nice colour that s. Happy running

[bilbob]

Nice colour that s.

How'd you know what colour it is ?

I've done the throttle bodies, better, still not great, but better... Valves will be next, once I got the clutch fixed as per my other thread in technical...

[fontana]

Hi, my S has done 90k miles, always on reg unleaded without a hitch. If super is making a difference I am at a loss.

As I understand it, super unleaded doesn't make the kind of difference you notice when riding.
It's more to do with how much better it is for the top end of the engine.
Reduced carbon deposits in particular.
That's just what a mechanic once told me.

[Humbug]

From the owner's manual:
Recommended fuel grade Super Plus unleaded (98 RON/88 MON)
Fuel grade, usable with power - and consumption - related restrictions Super unleaded (95 . RON/85 MON)

From that I would assume you lose both power and increase fuel consumption.

[slparry]

My K12GT gets noticeably better MPG with 98/99 Unleaded, but only when on a long journey. So when I'm doing the motorway slog up to Glasgow from North Wales I use Shell V Power etc

The RT was the same too, I guess newer generation engine with all their knock sensors and fancy computer timings can make a use of such elixir's. The S's have quite high compression ISTR so that's probably why it's "recommended"

[SP250]

My 2001 bike owners manual states super (premium) grade fuel - min octane 95 (RON) or 85 (MON).
Not 98 octane.