Bing CV Carburetors, Part 1 of 2 parts
basic mini-overhaul can be done with the carburetors in
place on the engine.
READ Article #6 on the R75/5
carbs....some really IS pertinent to all the CV carbs:
READ: http://bmwmotorcycletech.info/bingcv-2.htm That is Part 2 of the article you are reading now.
Below is a website in which you can enter your carburetor
model number, and get a chart showing all the component
The Bing CV carburetors are moderately complicated in HOW THEY WORK. BUT, there are only a moderate number of places in these carburetors where you probably could run into trouble in working on them. For the 'Newbie', I advise reading all of the carburetor articles completely through, even though you will not likely understand everything at first read. Once you have overhauled your first Bing CV carburetor, you will probably wonder what all the fuss was about.
NOTE: The float needle tips
tend to get faint grooves in them after a lot of miles and if a rubber-tipped type
the tip "rubber" material gets slightly harder, and gasoline tends to slowly (modern gasohol especially)
deteriorate them, and then the needle
tip does not seal well, causing the bowl to overflow onto
your foot. This can also happen if a TEENY MICROSCOPIC particle
of dirt gets into that float tip and mating seat area.....and
also if the float deteriorates enough. The
stock float and float needle probably should be replaced
every 30,000 miles. It is VERY common to see a carburetor overflowing onto your boot. Most Airhead owners have had the problem at one time or another. The fast fix is to turn off the fuel petcock(s), remove a bowl, and jiggle the float up and down with the fuel ON, to flush out any particulate matter in the float needle-seat area. It is important to keep the fuel tank clean, and as the tank ages, the interior reddish-brown lining deteriorates, clogs screens, etc. The rubber fuel hoses also deteriorate INternally, allowing teensy bits of rubber material into the carburetors, where they can cause float needle hangups, as well as plugging the idle or main jet. Use of aftermarket fuel filter(s) below the petcocks is almost a necessity now, with the aging bikes. Information on screens, filters, updates, etc., is elsewhere's on this website.
NOTE: Except for the earliest carburetors with no plunger on the float needle (no rubber tip on the needle either), if you accidentally left the teeny wire clip off the float needle and float, the chances are that the float system will work just as it is supposed to. You COULD, however, have a situation where the needle ‘stuck’ to the needle seat, and no gas flowed, that is one of the reasons why that wire clip was added to later carburetors. FYI, I used to purchase these wire clips about a dozen at a time, and I used to need one every few months when I had the shop. It is ever so easy to have one flip someplace while trying to install or remove to a new needle, and once they 'go someplace', they are near impossible to find. I used a 3 power magnifier on my eyeglasses, and always did the work on a piece of old white bed sheet! I tried magnets, some help, sometimes not.
On the EARLIEST carbs, the needle was all-metal. Bing had some problems and made several changes, approximately at the same time. The needle was changed to some sort of rubber-tipped type; the needle lower end was drilled, the needle got an internal spring loaded-plunger with a teeny hole at the bottom end, on the side, and the tiny wire clip was installed. Besides what was mentioned earlier, I ALSO believe that Bing incorporated the spring loaded plunger so that the fuel level sensing was more accurate, and so the needle would wear LESS, as less pressure was needed to close the orifice off, but more was available. That is, the LEVERAGE is such that as the fuel level rises, the pressure on the seat increases rapidly, compared to a very small fuel level increase. This is difficult to see, and a nerdy point anyway.
I also believe that as the plunger tip wears, which it does and the wear shows as a ring, the needle, being loose-enough in the vertical well area it fits up into, could cant sideways a bit. That MIGHT allow the grooved fuel shutoff needle to hang-up ever so slightly in the SEAT. Since only the needle weight, plus weight of fuel, and maybe vibration, etc., was going to be moving the needle downwards to let fuel in, Bing incorporated the clip, so as the float assembly went down as fuel level dropped, the float assembly positively pulled the needle off the seat.
NOTE: Replacement of a float needle SEAT is rarely needed. Detailed information is here: http://bmwmotorcycletech.info/bingcv-2.htm
****That clip is not used on the models 64/32/1-20; but it is possible to install them though.
The later float needles lower end has a spring inside and a tiny plunger, and the plunger has a tiny hole in it, that the wire clip fastens to this end part, and the plunger rotates easily.... some may find it a more than a little bit of an annoyance reassembling these. When installing the float, float pin, float needle and that tiny wire clip, they must be installed as an assembly, a bit tricky, especially if the carburetor is right side up, but doable. I suggest a white sheet under the carbs, in case you 'loose' that wire clip or needle. I highly recommend that you order SEVERAL of these wire clips when you order floats and float needles, as they are SO easy to lose. ALWAYS replace the float needles when replacing the stock float and vice-versa. When the float needle tip gets bad, the carburetor will leak on your foot, the mixture gets very rich, and the mileage goes way down.
***A very rare problem is a float
needle that seats irregularly, yet a new needle,
sometimes someone even replaces the needle seat, does not
fix the leaking. INSPECT the float tang...it
needs to be flat and NO irregularities in its approximate
center where it contact the bottom of the float needle.
This is very rare since most people have to replace
floats long before this wear is noticeable.
BMW dealers prices are generally
CHEAPER than Bing prices.....and you can NOT depend on
Bing USA parts being of the same quality as the BMW sold
parts. Be careful! .....and do NOT use
Stromberg diaphragms!...except in emergency.
Do NOT!!!...use anything but BMW Dealership or Bing Agency furnished BMW diaphragms:
You may run across articles that say that you can substitute Zenith Stromberg diaphragms, used on some Volvo's, ETC., for certain Bing diaphragms. You also may find that if you do this, they may work OK>>>BUT, MAY work marginally. There are differences, in material/thickness that do NOT seem consistent. The Stromberg CD150 diaphragm does physically fit the 32 mm Bing CV; and the CD175 does physically fit the 40 mm Bing CV. DO NOT USE THESE....unless in emergency.
With some Airhead carburetors BMW does not offer just the diaphragm, and wants you to purchase the slide with the diaphragm attached. This may occur with the models where the diaphragm is attached by a pressed-on nylon ring. If you want to, you can purchase the diaphragm from BINGUSA. You CAN pry the ring off without breaking it ....if you USE VERY HOT WATER, EVEN BOILING WATER, to soften and expand the ring. Be gentle, do not try to open the ring too far.
I recommend you
do NOT get carburetor rubber parts from BINGUSA; get them
only from a BMW dealership, they will be correct color
and type of rubber, etc. It would be better if you obtained the diaphragms from BMW dealerships too. BMW dealers prices are generally
CHEAPER than Bing prices.....and you can NOT depend on
Bing USA parts being of the same quality as the BMW sold
parts. Be careful! .....and do NOT use
Stromberg diaphragms! except in emergency. I have a few reports that seem to indicate that Bing themselves, or places that sold them saying they are Bing parts, might have substituted Stromberg diaphragms at times. NO PROOF, yet.
Many diaphragms have a downward facing tab that fits into a small recess in the slide itself. Diaphragms have a somewhat larger downward facing tab that fits in a corresponding slot in the top of the main carburetor body. Tabs and slots must line up during the actual fitting of the parts, and it is easy to accidentally rotate the diaphragm when putting the carburetor top back on. When assembling the diaphragms to the slides, be careful that you assemble things concentrically and carefully. If the needles are still in place, be extra careful not to bend them!!! Tighten the top of the carburetor screws evenly, coat the threads and underside with a WEE tab of antiseize, and do NOT overtighten..
With the central jets parts assembled, some care and wiggling may be necessary to install the slide and needle assembly in order to get the needle into the lower brass tube area. NOTE that many have initially assembled the atomizer jet wrongly. In the Bing CV carb, that atomizer must stick UP INTO THE CARBURETOR THROAT. If you assemble wrongly and then put a wrench and some force onto the central jet assembly, you can destroy your carburetor.
The central jet assembly top-most piece is a tubular brass part with some holes (this item is called an atomizer). This loose part (as you begin reassembly) fits directly above the tubular part called the needle jet. This atomizer must stick up INTO the carburetor throat, and only ONE end of it has the correct diameter to allow it to fit up into the throat. A problem can come about if one has the slide, diaphragm, and its wiggly needle already in place in the carburetor, and you now try to install the central jet assembly. First, be sure that the black rubber O-ring on the central jet assembly is in good condition,... if questionable, replace it, and use a wee bit of silicon grease to help its installation, AND on the outside of the O-ring (I also place a WEE bit on the threads of the jet assembly) so the jet screws upwards easier. Clean things, including the cavity, first. Regarding the mentioned potential problem: When installing the atomizer, ETC....be VERY careful that that the proper end fits into the throat, and that the needle does not catch the edge of the jet....you might not notice, and then screw the jet upwards, bending the needle...or worse yet, applying too much force and breaking the threaded carburetor boss. NO excessive force is needed here!!! SO, if the slide with its needle is already in the carburetor, be especially careful installing the central jet assembly.
Slides are reinstalled into the carburetor clean and dry, and the lower jet assemblies that the slide needle fits down into, really should, ideally, ALREADY be in the carburetor!! If you are careful, see above paragraphs, you will be OK.
When assembled correctly, the slide, which has two holes at its bottom, off center,
will have those two holes facing the cylinder
head. Slides work OK even when fairly well
worn. Bing has been offering some slides
with O-rings. They are quieter, in a few instances of
Rather often the brass atomizer part
that sticks upwards into the carburetor throat does not
fall downwards and out when the central jet assembly is
removed, or does it later when you are not looking!
Use a toothpick or similar to gently dislodge
it, or a tiny screwdriver carefully on the top side, to push it downwards. It is easy to lose these parts, so do
NOT! Remember, I recommended an old piece of
white sheet under the carburetor if on the bike. Once in
awhile, that brass atomizer part does not seem to want to
go into position...it is usually just a wee bit of crud on
it or in the carburetor body hole. Insert the
atomizer as squarely as you can after cleaning the hole and
atomizer, and it will install OK. Remember that ONE
end is slightly smaller than the other, and only that end
CAN fit. As always, be sure all parts are clean when re-assembling the carburetor.
One should remove only the necessary
parts, then spray into all the jets (pilot jet, mixture
adjustment hole, bowl jet, central main jet assembly),
etc., with a strong
carburetor spray, and let sit awhile, then spray again in
every direction possible through those holes. I prefer Berryman B-12,
in a version
called 'Carburetor and Choke Cleaner' for this job.
This is a very strong solvent mixture that actually
dissolves most all of the deposits from gasoline, which
many other spray solvents do not. Common brake cleaner spray is BAD, as it is not powerful, in fact it is quite mild for cleaning. You might
consider spraying all the metal pieces, then flush with a
common spray brake cleaner or equivalent. I do
recommend removing the central jet assembly, it tends to
get crudded up, often with 'black' stuff. Be careful,
as has been cautioned above, when replacing. There is an O-ring on it that must be in good condition. Same for idle mixture and idle pilot jet.
Some Bing carburetors, such as the
R60/6 and R60/7, use an acceleration
jet assembly in the central assembly, these parts all come
out mostly at one time, same as those carburetors
"ENRICHENERS"...yes, a whole choking section on this subject:
pieces are easy to mix
up and get installed backwards...or get the left and
right carburetor enrichener parts mixed up. A good rule is to
do both left and right carburetors at the same time. Your
bike could ALREADY have them wrongly assembled!
enrichener parts orientations:
The brass shafts that
operate the enrichener are stamped in the inner ends, L and R for Left and Right carburetors. The stampings can be a bit vague, see above photo on the right. Some late models (well after early /5 CV carburetors) rotating thick metal discs have an elliptical hole, and 4 smaller holes, one of those 4 MAY be a
bit bigger, and some may have one or two blind hole depressions not drilled at all. The holes MUST be clean/clear! There are
numerous types of the discs, some will not be machined
with the elliptical hole through the disc...and different
holes sizes and arrangements and even a special large brass washer plate may be seen, that is, later versions may have a brass thin disc on the other side of the thick disc, it is not shown here.
If you were to have the LEFT carburetor enrichener unit off the carburetor, and put it in front of you, upside down...that is...you are facing the inner (disc) side...and oriented so the round protuberance of the outer casting is TO YOUR RIGHT, and the LEVER is UPwards to its stop...about 1:00; THEN, the elliptical hole of the disc is roughly opposite the upper left casting screw hole, say 11:00....and the 4 tiny disc holes are roughly to the lower right....say 5:00.
For the RIGHT carburetor enrichener unit, as in these various photos, for the SAME orientation of casting and lever...the disc is REVERSED...that is...the 4 holes are to the UPPER LEFT, and the elliptical hole is to the lower right.
Here are some photos that will further explain things. These are from RIGHT SIDE carburetors.
The above photo, marked
Yes, you could press it all apart and fix
Just below is a photo of a CORRECT
Later model Bing
CV carburetors have two-piece cable levers.
It is possible to WRONGLY install the two metal pieces. It is annoyingly
EASY to overlook this, and you won't notice until you have
the carburetor fastened to the engine. Lever parts can be installed upside down AND/OR reversed in
position. In BOTH Left and Right carburetors,
the part that has NO notch (no slot)
for the installation of the cable wire, goes onto the carburetor enrichener or throttle shaft first, and note the enrichener here with its offset facing the
carburetor body. The outer part, that DOES
have that notch (slot),
can be installed wrongly, flipped-over if you will.
Install it such that the notch does NOT
face upwards during cable operation. Here are photos of how the later
model levers and springs look when
installed properly. Note how the short tang end of the enrichener spring fastens to the top, and further notice how that spring is on top of the enrichener lever, not the underside. To see why I install them this way, actuate the choke and note that the spring is not interfered-with by the lever, etc., as it moves.
This below photo of the controls side is from a LEFT side late model:
NOTE that for a
smooth AND PROPER enrichener operation, the enrichener needs to be
faintly lubricated, cables good, and operating lever cable
lubricated (IMPORTANT or cable can break strands!)... and if you have them, the T barrels under the
fuel-tank where the one cable from bars splits into two, in good
condition. There is an O-ring internally on
later enrichener models. I lightly silicone-grease that O-ring.
In one early version of Clymer's manual that I saw, in the early
section on how to start your motorcycle, Clymer's has the
operation of the choke lever (on the early models where
said lever is on the clamshell of the air cleaner housing),
BACKWARDS. The truth is that the
lever must be HORIZONTAL for the choke to be OFF....and
DOWN for choke ON (starting). Clymers fixed this in later versions of this manual, although I did not check all sections of the manual. Maybe I had something to do with fixing that first mention?!?
The enrichener (choke) is held to the carburetor body by 4 screws. These screws are infamous for loosening, and the gasket can then get sucked-in a bit, and the carburetor not work correctly, even with the choke lever off. If the carburetor is still on the motorcycle, I recommend, that once the throttle and choke cables are removed from the top of the carburetors, that you loosen the carburetor adaptor clamps and rotate the carburetor to allow the tightness of these 4 enrichener screws to be checked. If loose, either tighten; or, remove and use a wee drop of Loctite blue on the theads and then reinstall and tighten them. They CAN be tightened without rotating the carburetor, but it is typically a big hassle, even with several types of offset screwdrivers. If you wish, you may use the faintest possible smear of some sort of NON-silicone gasket sealer on both sides of the gasket. REALLY faint! Gasgacinch; Permatex Form-a-gasket (non-hardening), etc. NO RTV HERE. The reason is not to prevent leaks directly, but to help prevent the gasket from sucking-inwards, which then DOES cause leaks. I do not use any such sealants, but I do, during overhaul, make sure the cover and body it fits to are FLAT, with NO proud metal. I surface the cover, disassembled of course, on 220 grit paper; and, use a very fine file, very carefully, on the body mating area.
***Do not remove the throttle butterfly valves unless the shafts are really worn or leaking, as they are O-ring sealed, the screws peened, and the shafts can still be leakproof with a fair amount of side play due to the presence of the O-ring. To test for leaking, spray the shaft area from the outside of the carburetor, where the throttle lever attaches, with brake cleaner, while engine is idling. The idle speed must not change. If you do change the shaft O-ring, DO coat it, a bit more heavily than faintly, with silicone grease. They will then last almost forever, and operate smoothly. If you DIP the carburetor into a cleaning tank for any period of time with the usual harsh carburetor chemicals as used by professionals, you will HAVE TO replace the shaft O-rings. If the shaft is removed, then you must decide on the screws, to replace or not, to peen or Loctite them.
butterfly can be put in backwards. Do
NOT!!!! That is why I previously said to mark
the butterfly!..top, rear...or similar. This is a
CRITICAL point. HOWEVER, I highly recommend you check yours, as maybe they are already installed wrongly!
The fitment of
the lower edge (and the sharp shape at that point) of the
butterfly is critical where it comes close
to the the idle passageways holes at the carburetor
bottom. Putting the butterfly in backwards will
eliminate any chance of proper off-idle throttle
performance. This is doubly
important with a dual plugged machine in which the
butterfly is more closed at idle. If you
install a butterfly wrong, you will NEVER have a good
stable idle. When installing the butterflies... as you slowly tighten the two
screws, you must lightly
press the butterfly with a finger, into the main carburetor bore,
to align the butterfly...it is important that it fits the
bore very evenly, and for minimal clearance (shine a light
through the carburetor as you look from the other side). You may have to unscrew the IDLE STOP screw at the throttle lever some, to close the butterfly valve enough for a proper look-see.
The needle jet, which looks like a
machined brass tube of two basic diameters, and is often
marked with a number, such as 2.64, 2.66 or 2.68, fits with
the small tube portion upwards and its slightly curved
[internally] end downwards. Above that part is the
atomizer, which is a machined brass part of three differing
diameters, the slightly
smaller diameter goes upwards and fits through AND
INTO, the carburetor venturi (throat), and its
lower portion has the holes. On RARE
occasions this part might not seem to fit and does not seem
to want to poke up through the carburetor into the venturi.
If the smaller diameter end is up, the side-holed end down,
this is correct, and you may have the part slightly tilted,
or, tilted and under a tad of too
much pressure from the 10mm wrench area below. You
can install that atomizer by itself, and hold it IN the
throat, perhaps using a toothpick to get it properly into
position and then fingers to hold it in the throat, as
you assemble the lower parts.
The central jet assembly O-ring, with
the faint smear of grease, will reduce friction, and you
should be relatively gentle on the force you use on the
10mm wrench, just barely tight. Antiseize or silicone
grease on the brass threads make for less
corrosion and seizing possibilities. Remember that
the carburetor body is made of a soft and not overly strong
material....zinc probably. The danger is in cracking that
central carburetor boss. I grease the threads
VERY lightly, silicone or anti-seize. Those
that over-tighten the central jet assembly, and fail to use
a lubricant or anti-seize, are asking for seizure, years
When replacing rubber O-rings which you must push over threads, you might have the thought that the threads might cut the O-ring...yes, they could. The slightest cut will eventually expand to a wide cut or break, and leak. A simple way of avoiding that possibility is to not only grease the parts with a very THIN layer of silicon grease....but to FIRST wrap a single layer of any sort of tape around the threaded part, and THEN slide the O-ring over it! I use my smooth thumbnails to push the O-ring into position, sometimes using a teeny SMOOTH, totally NOT SHARP, dental hook, especially for the last bit of movement into the groove for it.
When installing or removing a slide needle, the early common type of needle is the twist/push-pull/turn type. For them, the proper method is to clean them and your fingers, so they both are clean and dry, and grip the needle tightly with thumb and forefinger, and rotate left or right, pulling slightly downwards or pushing upwards. EACH 90 degree rotation will allow ONE needle notch of change (if also pushing or pulling). UNDER NO CIRCUMSTANCES BEND THE NEEDLE. Rotate one direction, then the other, as required. Some may find that a thin piece of leather will help. NEVER use pliers!!! ONE (1) 90 degree rotation per so-called needle position!
Be sure both carburetors have the needle sticking out of the slide the same amount. Use a caliper, and measure closely. ***I HIGHLY recommend that you check the slides/needles for distance, to be sure they are the same, as well as to write down the distance, BEFORE removing or installing or changing the needle position. You cannot 'see' the needle position on the early style, it is done by feel, and having a measurement (you need to be accurate to maybe +- .015") may save you some considerable hassles. I measure them with a common vernier caliper. You can measure the underside of slide-to-tip distance, or, the distance from top of slide assembly 'tube' to needle tip. Needle position (there are typically 4 positions available) is measured from the top slot position of the needle. Most needles are in the #2 or #3 position from the top.
The other, later type of needle is not held in by the hidden clip in the same manner. There is a screw in the top of the slide. Remove the central screw from inside the slide, and turn the slide over. The needle should fall out the top into your hand, with a little clip on it around one of four positioning slots. Later needles may be aluminum, and if the clip grooves are worn enough so the needle can move up and down with reference to the clip, easily, replace that needle! NOTE!....The SLIDE needles should be replaced at the 60,000 mile intervals I recommend, or tad sooner, and always with the associated needle jet. There is a particular problem with the aluminum or similar needle material on some 1985+ models, in 32 mm size. There may be some other carburetors with this problem. The NEEDLE grooves WEAR, due to the type of metal used. If the groove wears enough, the needle will not deliver the properly metered fuel. Watch for this, it is little known. Replace the needle and the clip! You can get weird symptoms, even backfiring, if things wear enough. Check BOTH carbs!...they do not, for whatever reason, wear at the same rate.
The carburetors should be mounted
squarely to the motorcycle. View from the top, and a few
feet to the rear of the bike. Do NOT tilt the tops
towards, or away, from the motorcycle.
CARB TOP STAINS (and lean mid-range mixtures SOMEtimes)....and leaky top plugs:
Fairly often I see carburetor top stains where they join
the body of the carburetor. The tell-tale sign is a brown
(usually) stain around the diaphragm joint interface,
caused by some tiny gasoline weepage. I was never
bothered by this, as the 'problem' is sporadic and
minuscule. However, Oak
sent me (in 1984!!) a bulletin he made up describing this
situation as not necessarily being caused by the lack of
the diaphragm acting as a seal, but rather that the
compression of that diaphragm was insufficient for a
COMPLETE sealing. He recommended removing the carburetor
and flat sanding the carburetor top itself, with 220 grit wet type paper,
kept wet with water,
figure eights, carefully, until the groove, which he said
was 0.155 to 0.156 inch deep in the troublesome carbs, is
reduced by about .007 inch. He said to shoot for a final
depth of about 0.147 to 0.150. Remove all grit. I have done
this to several carburetors, and it DOES stop the staining.
Frankly, few of you have the gauges to measure this, so you
could try just a few
figure eights. TEN is appropriate, LIGHT medium pressure. Do them EVENLY. Once the fresh sanded surfaces
are evenly fresh all the way around, that is likely
enough. Do not overdo this. Clean and reassemble.
LEAKY TOP PLUGS:
HARD STARTING, maybe ONE carb
does not work well initially, then works OK after engine running
& throttle opened:
If you have done most everything, and you have problems starting the bike, consistently hard starting, or maybe ONE carburetor is acting up, that cylinder not firing (maybe even until engine warms a bit) and throttle is opened.....check that the enrichener was properly installed, no matter if the dot-dimple on the shaft looks correct.....and if still a problem.... see if the butterflies were properly installed. Not only is this to include loosening the screw whose bracket keeps the shaft in place, but loosening the butterfly screws (a problem if peened, if not, when tightening, use Loctite BLUE), and be sure the butterfly will completely seal to the carb bottom (idle rpm screw loosened A/R).....and tighten things again. If the butterflies are reversed, you will never get proper operation.
If you have a R75/5 that is particularly a bear to start (or, one carb is not working at startup), and everything else checks out fine, be SURE to check the slides, to be SURE they are BOTTOMING fully, and not hung up slightly. Install the springs above the slides. This problem is rare, but has been seen on them, and VERY rarely on later carbs. Polishing the slides and inside carb body can help. There is a very complete article on this website about R75/5 carburetor problems: http://bmwmotorcycletech.info/earlybingR75CV.htm
Sometimes there are complaints of hard-starting bikes. The owners have checked everything, including valve adjustments, compression pressure, spark plug wires and caps, coils, everything....and the bike still does not start OK. Check the slides on CV carburetors, be sure they are fully bottoming.....there is a spring on top of the slides on some models, to help with this.
ON all models, and the Independent float KITS too;....the floats are adjusted by bending the tab that the float needle (and wire clip, if used) attach to. I have found a TINY screwdriver does this OK, and seems to work better than unwieldy long nose pliers. Do one carburetor at a time. BE GENTLE AND CAREFUL!!...do it evenly too...not at one edge, which bends the tang on an angle you don't want. In other words, keep the tang flat and square. It is spring-y, so eyeball your work. After making a small change... turn gas on, lift float gently and SLOWLY with protectively gloved finger, until the gas flow JUST stops. At THAT point where the gasoline JUST stops flowing, the top of the stock floats are to be parallel to the lower body of the carburetor. I allow as much as +- .020 inch. I have done some fine-tuning by playing with the float level, I suggest you do NOT. Some folks find it easier to lift the float until the gas stops flowing, and then very very gently lower it until the gas JUST flows. This MAY well be the preferred method, as it eliminates the effect of the spring loaded lower tip on the later type float needles and eliminates any play in the pin and hinge holding the floats in the carburetor. For the KITS, the adjustment is the same, but the measured distance is .412" from either lower arm edge to the body.
I have information on this website ....originals of some Bing documents, some of marked-up copies, crude, but useable...all of various Bings sheets on installation and adjustments of the independent floats KITS. Here is a hyperlink: http://bmwmotorcycletech.info/bingindependent.htm
Be gentle and careful about doing any
bending. Float level affects richness-leanness and gas
NOTE and HINT: On earliest models the band clamp at the carburetor throat inlet should have its adjustment at the TOP...or, at least not at the bottom. The models most affected are those with the plastic tube having slots in the band-clamp area. If the band adjustment is not above the bottom, the breather output oil may drip on your foot, depending on if there is a slit or not on the tube; this was particularly so on the earliest models.
Additional information on Bing CV carburetors will be found at http://bmwmotorcycletech.info/bingcv-2.htm
to 12-07-2002: mostly
© copyright, 2014, R. Fleischer