New member and fuel efficiency

[roryjohnson]

Hello Everybody

My name is Rory, I just bought my first BMW R65 1980, very happy with it! However, Im a bit worried about the fuel consumption. My first tank full of regular unleaded ~13 litres only got me 150km, riding in the city and one long excursion at ~ 100km/h with a passenger.
Is this the normal consumption??

Also - Im finding it pretty tough to get started in the morning. It seems to get flooded quite easily, takes ages to start, and then tries to conk out when i stop at the traffic lights, unless I keep giving a little gas. Any suggestions / tips etc?

Thanks! happy to "meet" you all

Rory

[Bob_Roller]

Welcome Rory, I'd suspect the carbs need looking at, any idea if the previous owners performed any maintenance on the bike .

The bike's 31 years old and a good chance that nothings been done to them .

[Graeme]

Does it have an LS front end? Twin disc's.

[unibober]

Nice LSU hoodie!  I as well would suspect that the carbs need a rebuild or a balancing.  Are you using the choke with throttle as that seems to cause problems. Beautiful bike ya got there.

[steven m]

Nice bike.  Re your fuel consumption, keep in mind only half the gas tank feed the carbs!  The other side never drains.  I think BMW made some lame excuse about it being an emergency reserve.  Ha ha.  As far as starting goes, I usually put it on full choke and crank it with no throttle to prevent flooding.  After it starts, I let it run for about 15 seconds and then pull it back to half choke.  Still no hand throttle.  Ride normally for a block or two and then turn off the choke.  Air cooled engines tend to be a little cold blooded...

Of course a good tune up and carb balance is a good idea.

Steve

[nothing]

Regarding the hard starting, it sounds like your valves need adjusting. If you haven't done so since buying the machine, do it before riding another kilometer.

[Graeme]

I usually put it on full choke and crank it with no throttle to prevent flooding.  After it starts, I let it run for about 15 seconds and then pull it back to half choke.  Still no hand throttle.  Ride normally for a block or two and then turn off the choke.  Steve

Works for me.

[Barry]

Welcome Rory,  

Nice looking bike.

Not being able to think in km and litres I converted your numbers to 32.6 MPG Imp which is not too good.

You should get 50MPG imp or more on a decent run as long as your not flat out all the time so as others have said the carbs probably need looking at.

As well as a general clean I would check that the jet sizes and settings are stock, replace the O rings and carefully inspect the needles/needle jets which are known to wear.

As for starting in cold weathers most owners need full choke to start then back off to half choke as soon as it fires then off altogether pretty soon after.  It s normal to need to hold the revs up with the throttle until the engine is warmed up, say at least a couple of km. There would be something wrong if it would idle straight after a cold start.

[roryjohnson]

Dear All
Thanks a lot for all these helpful comments and suggestions, I'm going to take it to my local and have the carbs checked out.
As far as I know, the guy I bought it off more or less took the whole bike to pieces and rebuilt it, after a long stink in someones garden/garage. He seemed to know pretty well what he was doing, however he didnt mention if he had worked on the carbs.
Thanks and nice to meet you all!
Rory

[Darwin_R65]

My bike is close to reserve around 225kms sometimes 210, sometimes 265kms out of a tank on my 1981 R65. I run premium unleaded which in Oz is 94/95 RON.

John

[nhmaf]

~45 mpg (US gallon) is normal for stock tuned R65.
IT sounds like it is definitely time to adjust the valves, install new plugs and checkout the carbs  (also check that the air filter is clean).

[tvrla]

I get the impression it's running fine once warmed up?

That being the case, the o-rings are probably fine, but the main jet atomizer could be plugged up.

I'd also suspect the floats are getting heavy, allowing the fuel level to ride high. As a quick check, pull a float bowl and measure the fuel height - it should be about 12mm from the top edge.

And the third item to check would be the slide needle and needle jet - the two rub against each other and over time the orifice enlarges and the needle gets smaller allowing much more fuel to flow. You can't really tell by eyeballing, either measure or replace.

By the way - beautiful bike! It looks just like one I sold a couple years ago (and still miss).

[Lucky_Lou]

~45 mpg (US gallon) is normal for stock tuned R65.
IT sounds like it is definitely time to adjust the valves, install new plugs and checkout the carbs  (also check that the air filter is clean).

I recall the thread .."Post your mileage" and for what ever reason the UK bikes were all returning 50+ mpg i know theres a difference between US and Imperial gallons but not enough to explain the variance.
That said if you dont know the history of the bike i would definitely do the valve clearances rebuild the carbs and check the timing (is it electronic ??) a set of points and plugs wouldnt go amiss also change all the fluids.I bet Barcelona is quite nice if you need a hand i will pop over, if they ever get the snow off the runways that is...
BTW nice scooter.
Lou

[Dizerens5]

Rory I see your bike has the flat-top Bings. I've run my 79 on both flat-tops and dome-tops, both apparently in good condition and correctly set up, and found the flat-tops gave consistently better fuel mileage. Don''t know why.

[Barry]

Imp gallons are almost exactly 20 % bigger than US gallons so it's easy to convert US MPG to Imp MPG by just adding 20% :-

40 MPG US = 48 MPG Imp

45 MPG US = 54 MPG Imp

50 MPG US = 60 MPG Imp