The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: guyom on August 24, 2018, 09:03:58 AM
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HI ALL i am back again :
question 1: if you let the fuel line opens when you go for a beer, is there some fuel on the ground = YES OR NO ?
On my R65, this is the case :
so i changed the float needles... but nothing changes...
so i changed the floats... but nothing changes...
so i changed all the seals... but nothing changes...
so i changed the membranes... but nothing changes...
so i tried different setups.... but nothing changes...
so i carefully inspected the carbs for cracks.. but nothing changes...
SO ? ideas ?? hahaha... i am close to buy new carbs after spending 300$...
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Don't drink as much beer or close the fuel line and drink more beer! ;) ;) ;
FWIW
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haha yeah for now i have to switch off the line otherwise i can have just a sip... ;-)
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Guyom,
Check your fuel lines for leaks. If the outer cloth is wet it is time to replace with new 7mm tubing.
Test that the fuel shuts off completely when you lift the floats by hand with the float bowls removed. The fuel flow should stop when the line on the float is parallel to the bottom of the carb body. It should not require any significant force. If it still drips after setting the level the float needle seat ma be damaged. Some people have had luck polishing the seat.
Others have mentioned problems with the overflow tube in the carb float bowl being cracked or loose. Set the float bowl on the bench and fill it with fuel to test its integrity.
Good luck,
Brett
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HI Carott ! thanks for answer.. i forgot to mention that the line is also new... new filter also.
Indeed, the bowl are full of fuel so sounds like the needle does not stop fuel even new with new floats... i will check the seat of the float and polish it a bit with a dremel... (soft polishing ;-))
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also got another question (yeah, leak is just one problem, got 2 problems on the carbs) =
One carb does not return to idle when i turn the throttle but stay high... (2500-2800rpm) i have to turn the idle screw to decrease the rpm and then put the screw at normal.
Is it a diaphragm problem?
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On the seats I have always used a sharpened wood pencil with a little fine valve grinding compound on the tip.
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thanks sounds softer that my dremel idea ;-)
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The idle hang up problem can be carb related or it can be a sticking ignition advance. Given the issue you have with carb flooding there's a fair chance that the idle hang up is carb related so I wouldn't attempt to resolve it until you have a reliable fuel level and the idle mixture correctly tuned.
When idle hang up is carb related it's usually that the idle stop screw is opening the butterfly to far and bringing the transfer ports in operation when they shouldn't be. Why should the idle stop screw be opening the butterfly too far ? Possibly to compensate for an incorrect idle mixture either too lean or more likely in your case too rich.
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HI ALL i am back again :
question 1: if you let the fuel line opens when you go for a beer, is there some fuel on the ground = YES OR NO ?
I once sent a fairly intemperate letter to Bing on this very topic (yes it was that long ago in the time before emails). They replied "We do not make petcocks, we make carburettors. When you leave your bike, turn the petcocks off."
Never had a problem since, although quite why the Germans cannot design a needle and seat that works as well as the Japanese manufacturers is somewhat beyond me.
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Are both carbs doing this, or just one ??
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hi All thanks for your answers. So if i well understand : I have to turn the line OFF ;-)
And no just one carburetor : the left one. Also i added pictures of the set up of the new Floats ? are they correct like that ? thanks
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another one for the float needle
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Been 8 years since I had the carbs apart . Looks like the floats may be installed up side down .
Correct me if I'm wrong .
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haha well the carb is up side down, i read that the bottom of the float should be horizontal to the body of the carb... sound good... however in 5th gear = the motor cough meaning not enough fuel in the carb i think.
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Well, your floats are properly installed, But they are weighting on the needle and the little spring on the needle is compressed. So the needle closed BEFORE the float where parallel to the base of the carb...
You have to check the float level with the carb in position and fuel petcock open. Lift the float and check when it gets to stop the fuel flow. if the float is parallel to the carb base, it is OK.
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Agree.
While it's possible to do them upside down you have to be aware that the float valve has a spring load pin. Upside down is a method given in some books but it's no longer recommended.
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great ! Thanks to all ! so i can continue my investigation about a potential leak and idle !
G
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I was just reading a similar thread at bmwmoa and one of the posters reminded me of how I fixed my leaking bing once.
The fitment between the bowl and float must be very very close on these carbs because I managed once to tweak the float carriage ever so slightly once on reassembly. From then on it leaked continuously. The float was literally sticking/binding on the bowl. Eventually I deduced this and VERY gently tweaked the float sideways back to better center and the leaking disappeared.
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thanks i will try that too make some test and leak looks to stop... after 15 minutes... so i will try to fix the idle now.
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I fought a carb leak on one carb for a while. Finally found I had a pin hole from corrosion in the bowl. I was close to the over flow tube.
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My understanding is that the bottom of the float should be parallel to the body of the carb, but the carb should be held at a slight angle like it is mounted on the bike, not parallel to the ground. See Boxer2valve.com (Wunderlich) for the video on rebuilding the carbs on a r 90 to see what I mean.
FWIW