Dual-Independent "alcohol-proof" Float Kits
A Bing, NOT BMW product
Copyright, 2014, R. Fleischer
The MAIN advantage of these kits is that you do not ever
(probably) have to replace the floats. That does NOT apply to the float needles, of which there were two basic types, and the VITON tipped ones have the easy to lose
fine wire clip, same as on the stock carburetors, that insures
positive float needle operation.
If the original floats (which DO AGE) are really bad, and or the float needle is bad, things will certainly improve with PROPER installation of these PRICEY kits!...and THOSE are likely the HONEST and TRUE reasons that SOME find improvements with these kits!, including fuel mileage improvements.
Adjustment of these float kits is more involved than with the stock floats. These kits can have real nasty problems, so read all of this article.
Here is an introduction to these kits, and I will get much deeper into them after this section.
These kits were originally sold with reddish-brownish plastic bowls. Those bowls have been known to develop cracks, often microscopic, that cause weeping of gasoline. The latest Bing Independent kit bowls are zinc metal, similar in material to the original stock bowls. They are EXPENSIVE, and NOT available from BMW (BMW carb parts prices are often MUCH cheaper than Bing's!!).
****NOTE:The old method of turning the carburetor upside down for adjusting the float level is no longer used for the STOCK one piece white floats...but it IS for these Bing dual independent floats! At least per Bing's instruction sheets. However, by using one's finger, carefully, one can adjust the float bridge of these Bing kits, whilst on the bike...and Bing's latest sheets reflect both methods of adjustment. Note that adjusting even the stock floats using the upside-down method is very tricky, particularly with the sprung tip type of float needle. Best you do NOT use that method.
independent float conversions, here are some adjustment
With carburetor upside down the most outward part of the brass hinge unit, the top of its flat area, should be 10.5 mm and parallel to the base. AND...BOTH of these arms MUST be parallel to each other. For the old model 55 carburetors this was 8.5 mm. Once in operation, one could remove a bowl quickly, and the center area to top of the fuel should be very close to 1-5/32". NOTE that after first installing and adjusting one of these Bing independent float kits, they must be RE-ADUSTED after maybe a dozen hours of riding. This is because the float needle breaks in, and the effect of fuel on the needle and float. Quite frankly, I think the BRASS also tends to change a bit, something to do with its hardness and tempering grade I suppose. It is important that the spring loaded plunger on the float needle be in good condition, and the spring inside it not sacked out, or the mixture will be variable due to changes in the fuel level.
http://bmwmotorcycletech.info/bing-tech-bulletin-1984.pdf This is the original 1984 dated bulletin describing the new kit.
The original kits used metal (zinc casting) bowls. Later, Bing began shipping the kit with plastic bowls, of a dark-colored material. Those sometimes developed microscopic cracks, typically vertical-running in a corner. Later, Bing went back to zinc bowls. The zinc bowls were rather costly to purchase from Bing if you needed to replace a plastic one (and they stopped making plastic ones).
Bing promoted their new float system for transverse to direction engines, and for special industrial engines and ultra-light aircraft, etc., that had special inclination performance requirements. It is my belief that these kits were developed originally for small aerobatic aircraft, and only later Bing decided it could sell many more, perhaps at a handsome profit, to motorcyclists. As noted, I have the original Bing engineering bulletins on these kits, from the early 1980's...and most are clickable well above.
Bing furnished, through its Bing Agency International in the USA, another bulletin that explained how Bing wanted you to think about the kit's operation, using a glass of liquid as an example, as liquid sloshed back and forth, with acceleration and deceleration, and how, supposedly, this worked on BMW bikes (BUT....remember, our carbs are rearward and angled, NOT a transverse engine!
Bing said that there is a lean-ness, then richness, power changed, and you subconsciously added more throttle to compensate. I say: take this with a grain of salt!
"My Airhead motorcycle came with the
twin independent float conversion... why do the gurus
"hate" them? I also would like to
know what IS the proper procedure for adjusting the float levels
on carbs with this conversion, assuming I am going to do it
(and other inquiries.....)
Primarily, there is the lack of an BOWL "overflow" that has "guru's" (and may BMW?) most
upset. All the stock CV Bing carburetors, as delivered by BMW, have
an overflow capability at a vent port on the carburetor body, which is rather high up, This is in addition to the tiny diameter vertical 'overflow' (vent) pipe coming out of the bottom of the bowl. Neither of these may prevent some flow into the left cylinder, especially if the bike is on the side-stand, and the float needle is leaking a fair amount of fuel into the bowl, that is, at a much higher level than designed....or; thinking about it another way, the float & its float needle are NOT shutting off the fuel, as the float bowl level rises to the proper preset amount.
I passed on what I knew about this kits as far back as 1984, and I later did articles on these kits, including discussing the original engineering behind their development, which Bing would very probably prefer I not post. NOTE that BMW never installed them,... it would hardly have cost them anything...there are several reasons they did not, and I discuss most of them in this article.
While I am often considered as one of the so-called "guru's", I actually have nothing too much against use of these Bing Independent Float Kits, or alcohol-proof kits, or however Bing Agency in the USA presently advertises and sells them. Just be sure your petcocks work properly (don't leak internally either) ....and are in the OFF position (horizontal lever position), if using the side-stand; OR using the center-stand. Pay attention to my advice to always turn off your petcocks when the engine is off (Bing ALSO cautions this). This is especially important if using the side-stand. ****OFF is NOT "auf"!!!! if your petcocks are so marked.****You will have to adjust the flimsy float bridge in the kits a few times, perhaps only twice. Usually, after that, they settle down and are reliable. You will still have to replace the float needle now and then, perhaps 30K-60K intervals, same as with the stock floats. The twin independent floats in these kits seem to last forever in any type of gasoline or time and miles (NOT so the float needle).....but the adjustment brass-looking bridge is thin, flimsy, and is poorly heat treated. It is possible that this was done on purpose, to be fair about this. That brass-looking bridge needs to be adjusted properly at first install, and then once or twice more after being in use for awhile. Bing says readjust (implying once) after 5 hours, I say this is not enough, and should be checked again after maybe a month or more, and then maybe at yearly....or even longer, intervals; typically they are OK after they settle down.
BMW dealerships generally charge LESS for Bing carburetor parts than Bing Agency does, but the dealerships may...or may not... stock the independent float kit parts (as they are not BMW parts)...although the FLOAT needles are the same).
Details:At this point, if you have not looked at ALL FIVE bulletins/etc, links at top of this article, NOW is the time to do so. Read them at this point, before proceeding.
CAUTION!If you are not familiar with Bing carburetors, you need to know that the thin round metal rod that holds the float bridge to the two carburetor support bosses, goes into, and is removed from, the support bosses from only one side. The rod is KNURLED at ONE end. The OTHER end goes in FIRST. When removing the old rod, remove it knurled end first; using a very thin rod at the NON-knurled end, and a very tiny hammer or even the plastic handle of some tool as a VERY light tapping-impact tool!!...be GENTLE. You can devise a very thin rod for use as a punch, by grinding a nail, remove sharp end or reshaping it.
Under NO CIRCUMSTANCES put much force on that float rod. When installing a rod, tap it in or squeeze it in very gently. Remember: install the NON-knurled end of the rod first. That way, the knurled rod end goes into the knurled boss end, lastly.
Be truly careful. You will have a VERY bad day if you break a boss.
Be careful to avoid miss-adjustment of the bridge....it could then cause rubbing, or uneven, even angular, float operation. If you miss-adjust the bridge, you can get all sorts of problems, from flooding to mixture problems. This is NOT a difficult job, just be slow, cautious, careful.
Be careful about the two vertical float pins in each
float bowl....those pins have been known to be bent, and
need gentle straightening...otherwise the floats might stick at
the bottom (more, later on....).
I have also seen some floats with
poorly peened tubes in the floats themselves, and easy to fix.
Here are some hints from my own work on these:
First, turn the carburetor upside down.
Adjust the tab on the bridge piece and the arms themselves, so
5. If the carburetor is OFF the bike:
The part of the arm to look
at for the parallel-ness is the BOTTOM of the arm, as viewed as if the carburetor
was ON the bike. BOTH arms must be equal and parallel.
For 5. and 6: When using a small screwdriver, you bend the tab against the steel retaining pin. You will see
what I mean when you try to figure out how to bend the tab. DO NOT BE HAM-FISTED.
7. Note: A little known problem with the individual independent floats themselves is that there really is a top and bottom to SOME of them. Bing ignores this. Because of the tight fit at the bottom combined with the slight upward slope (and very close to the bowl rod) of the bottom of the 'new' float bowls, the floats CAN, sometimes, 'stick', to the bottom of the bowl. They can also stick at the bottom if the pin is bent even slightly!! Usually, but NOT always, this 'potential problem' does not cause a problem due to the motorcycle vibration during operation.
I suggest you be careful to install
the floats on straight up pins. Another thing to watch for is that the center metal
pipe area (that is part of the float itself) is such that the
broad-rivet head of that pipe is DOWNWARDS, towards the bottom of the bowl. It is possible to actually 'feel' this float grabbing at the bottom, especially if the rounded larger head area is up (or pin bent), instead of properly down...which raises the floats very slightly off the floor of the float bowl. I had one bowl that I saw that this was exceptionally poor....so I installed the floats rivet pipe head
downward, and I put a very small and very thin washer over the bowl's
8. http://bmwmotorcycletech.info/bing-tech-bulletin.pdf has a sketch, near the bottom of the page, of the float bridge adjustment with the carburetor on the workbench, upside down. The RIGHT end of the arms (the two arm ends MUST be parallel) have a wider area on the right-most part of those arms. You could describe it as wider by a small amount. The UPPER surface of that wider part must be not only be parallel to the carb base body, and both arms even to each other....but the DISTANCE from this upper surface arm part to the carburetor base must be 10.5 mm...which is 0.412 inch. This covers all the CV carb models used on our Airheads (there is a different specification for ONE model of Bing not used on the Airheads....it is listed on the sketch above, for model 55 carburetors, where the distance is 8.5 mm).
9. After some hours of use, reset the bridge if needed, at the least do check it. The bridge will change its adjustment slightly due to its heat treatment (I THINK),....and some settling-in of the tip of the float needle.....and teeny changes in the internal float needle spring parts, etc. You will probably do this with the carburetors attached to the motorcycle, rather than remove them to the workbench. Mind my previous comments on how to do this with the carburetor ON THE BIKE.
NOTE that you WILL have to change the float needle now and then, perhaps at 30,000 to 60,000 mile intervals, and rechecking adjustment is mandatory at that time...same as a stock carburetor. The adjustment of these twin independent float kit units is, as you have seen, more time consuming than the simple adjustment method of the stock floats.
The lifting of the float bridge to see the exact contacting of the float needle pin plunger end is tricky. Certainly, no matter how done, you must be VERY gentle with the fingertip....to see the correct adjustment.....and to NOT distort the brass bridge. It might be a lot easier for you to turn the gas on and lift VERY gently to the point the gas JUST shuts off, then lower your finger to the point the gas JUST starts flowing. That is the parallel point....or should be. Be careful with that bridge. It is flimsy, and if you lift at one arm with any real pressure, you can distort it.....and both arms must remain parallel to each other, as well as the final adjustment being parallel to the carburetor body.
10. Once installed and in operation, one can turn off the fuel petcock(s), remove a bowl quickly to avoid excessive fuel getting into the bowl, and the BOTTOM of the BOWL CENTER AREA to the TOP OF THE FUEL should be very close to 1-5/32". This was for a 40 mm Bing CV carburetor. I have not checked a 32 mm. When I do, will post it here.
Copyright, 2014, R. Fleischer
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