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EARLY R75/5 BING CV CARBURETORS
.... problems........ including idle problems.

http://bmwmotorcycletech.info/earlybingR75CV.htm

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© Copyright 2018, R. Fleischer

INTRODUCTION:

This article deals with problems with early versions of CV carburetors used on the R75/5. This includes getting the bike to start and to idle correctly as best possible.

A basic mini-overhaul can be done with the carburetors in place on the engine. This may be enough. Three articles, the one you are reading, and http://bmwmotorcycletech.info/bingcv.htm  ....and http://bmwmotorcycletech.info/bingcv-2.htm are not just about how to overhaul Bing CV carburetors. These articles are specifically designed to fully inform you what you need to know, as an Airhead owner/rider, about Bing CV carburetors.

While it may appear that the information in the below article does not apply to the later carburetors (except for information as to how the /9 & /10 and later carburetors are different from these /1, /2, /3 and /4), that is not so! The information in this article should be read by anyone that also works on later model CV carbs ...as some things are good to know ....such as about the springs that might be added, changes in parts, and problem area.

Before working on the R75/5 carburetors to cure what might seem to be carburetor problems, such as high or irregular idle rpm or inability to properly adjust the carburetors, it is important that the engine valves be set correctly, & the ignition timing be correct. Be sure there are no vacuum leaks at the throttle shafts.  Be sure the hoses between carburetor & cylinder head are tight & not leaking vacuum (spray with any volatile solvent ...must not be idle rpm changes). Never work on carburetors unless you are sure all else is OK!

This remainder of this article is only available for Airheads Beemer Club members. Please Log In..or..Click Here to join the Airheads Beemer Club, after which you will enjoy access this article and all members only content of the ABC web site. 

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The Dell'Orto Carburetor
BMW R90S Airhead motorcycles, other bikes, & some cars!
(Also covers Dell'Orto functions & operation; especially for needle/slide types.)

http://bmwmotorcycletech.info/dell.htm
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© Copyright, 2017, R. Fleischer (my portions only)

There are many sketches and drawings in this article. Allow time to load if you are on a slow connection. There are comments from me scattered in the article, note particularly that near the very end of this article is considerable information from me on adjustments for the R90S carburetors.

References:

In black and white:
http://web.tiscali.it/abosco/moto/carb/dellorto/dellorto.html

http://www.ducatimeccanica.com/dellorto_guide/dellorto.html

http://www.ducatimeccanica.com/dellorto/dellorto_manual3.html
That is a link to page 3 of that manual (you can modify that url for the home page or other manual pages), showing the fuel level adjustment. See also section 2, in the generic Dell information well below.

http://www.ducatimeccanica.com/dellorto_jetting/dellorto_parts_book.html

http://www.guzzitek.org/documents/carburateur/DellOrtoMAJ01.pdf

Besides the main article, below; which has my notes, etc., in it, you may want to overload yourself (?) by reading these two articles, which are from the DellOrto manuals themselves. These are .pdf files, so are very usable.

http://bmwmotorcycletech.info/dellorto_manual_features_and_tunings.pdf

http://bmwmotorcycletech.info/dellorto_manual.pdf

If you can stomach all this reading and absorb and understand it all ...you could become a DellOrto expert!

Be sure to see the information on the floats, it does pertain to Airheads, this is in section 3.2.2. See also near the very end of the long article below that you are reading, where there is my information on the pump setting and float setting, as pertains to BMW Airheads specifically! There are hints there too!

The following information article came from, I was told, the .startwin.com site, and was sent to me in a zip file, which I have unzipped, modified, and put below. I have been unable to find the author or person who might, or might not, have copyrighted this information, so as to gain official permission to place it here. This article, whatever its original source, now appears to be public property. I tried to make sure about that, so, on 10-06-2003, I sent e-mails to van Star Twin Motors, the Startwin.com folks, asking about use and copyright. There has never been a reply. I last viewed their website in November 2017, and there is nothing about the carburetors.

I have added my own comments to the article prefixed by ***, and underlined. I have corrected many typographical errors and misspellings in the original article ...and changed to U.S. type English spelling and usage. I have also eliminated some in-article hyperlinking, etc. There are places that my comments now are not all that clearly identified, as I wished to eliminate red color I used in earlier versions of this article, which resulted in gaudiness and an unprofessional look to the article; so this latest version generally uses asterisks and underlines for personal comments by me as well as for normal emphasis. I have also modified how the original's photos are formatted and placed, and added borders, and I also prevented wrapping of text around the photos.

The following informational article can be quite useful for those trying to understand how any carburetor works. While the information does not deal directly with Constant Velocity carburetors, it does deal with needle & slide carburetors, & a vast percentage of the information applies to all types.

 Gr000035  

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The Bing Dual-Independent "Alcohol-proof" Float Kit
>>>A Bing, NOT a BMW-sold-nor-installed product!

© Copyright, 2014, R. Fleischer
http://bmwmotorcycletech.info/bingindependent.htm
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The MAIN advantage of these kits is that you will likely never have to replace floats. That does NOT apply to the float needles, of which there were two basic types. The VITON tipped ones have the same easy-to-lose fine wire clip as on the stock carburetors. That clip insures positive float needle operation when the needle should be leaving the needle seat and allowing fuel to flow into the bowl.

If the original floats (which DO AGE) are already really bad, and/or the float needle is already bad, things will certainly improve with PROPER installation of these PRICEY kits! Installation is, however, somewhat tricky.  IN MY OPINION, installation of these kits when the old parts were worn, often considerably, is the HONEST & TRUE reason that SOME find improvements with fuel mileage after installing the kits.

Adjustment of these dual-independent float kits is more involved than with the stock floats. These kits can cause $$$$ problems, so, please read all of this article.

Introduction to these kits:
(I will get much deeper into them after this section)

I do NOT recommend Bing so-called alcohol-proof independent float kits for everyone. HOWEVER; if you are willing to fiddle with these, & understand the limitations & cautions, they are OK with me. Bing published, many years ago, that they gave increased mileage & performance due to stability of the fuel level during turns. I somewhat agree, but mostly only in an airplane or with serious racetrack use where the bike is leaned to truly extreme angles. These independent floats were originally advertised as being for engines where the carburetors were facing more left and right than on our Airheads...& more or less fore & aft. One must think about the way the floats are hinged & operate, & then you will see that Bing's old claims for our bikes were hardly reality. As to their NOT being affected by 'alcohol'; ....that may be true. But, as seen in my Bing article where I get into extreme long-term testing of floats in alcohols, alcohol-laced fuels, and a LOT more, ....alcohol is not the REAL problem that seems to cause deterioration of the floats, particularly a weight increase, and probably also the small center-of-mass change.  

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Bing Carburetors that pee gasoline onto your boot; or,
weep or leak onto the floor of your garage.....
How to do the Bing Dance!
Fuel foaming from vibration, particularly on GS models.
Float needle seat replacement.

http://bmwmotorcycletech.info/Carburetors-that-piss.htm
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© Copyright 2012, 2017, R. Fleischer

For float testing in depth: http://bmwmotorcycletech.info/bingcv.htm

For actual fuel level measurements & information on replacing float needle SEATS:
http://bmwmotorcycletech.info/bingcv-2.htm

It is very important to turn off the petcock(s) when you park your bike. This is so even if you have a late model Airhead that has the fuel-shutoff solenoid valve located on the inside of the cover over the starter motor (many have been removed, but the same caution applies). It is exceptionally important if you park your bike in a garage where there is a source of gasoline fumes ignition ...such as a water heater, ETC. We do NOT need to hear about BOOOOOM! We don't want fires, either!

Bing carburetors are commonly known to leak in several ways. The most common is fuel dumping on your boot from a grossly overflowing carburetor, typically from a side vent. Sometimes there is just a slow weeping or a slow leak from the very small hole in the bottom of the float bowl.

IF the leak is ONLY a tiny bit of weeping or leak from only that small hole in the bottom of the carburetor:
Remove the bowl, clean the outside bowl area with fine picks, solvent, etc. Use a taper tool of some sort, & give the folded-over pipe a modest whack with the tool & quite small hammer, with the carburetor bowl top surface down onto a flat hard surface such as a thick metal plate. This will re-seat & re-stake the tiny pipe. Only in quite rare instances have I had to seal the pipe interface.

There have been rare instances where that tiny pipe has split from frozen water in the bowl. If so, the pipe must then be replaced....unless you feel a bulging wallet ....then you can purchase a new bowl.

Similarly rare, there have been instances from another small but slightly larger pipe. This is the one coming downwards from the carburetor main body, that dips into a bowl corner "well". It also splits from water and freezing. This causes problems with the choke (enrichener) operation.  That pipe can usually be fixed by soldering a larger pipe over it, but be very careful in your work, and do notice if the downwards pipe has any side holes, if so, those must be maintained in operation.

The Bing Dance, Part 1:

1. Motorcycle is outdoors, or, otherwise away from flames, etc. Perhaps you are on a trip. Don't do this in your garage unless it is quite safe from water heaters that might ignite fumes, etc.

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Bing Carburetor FLOATS
and...FLOAT NEEDLES...
As used on BMW Airhead Motorcycles

http://bmwmotorcycletech.info/bing-floats.htm
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© Copyright 2015, R. Fleischer

Float needles:
Bing carburetors FLOAT NEEDLES, whether the pure slide type carburetor, or the CV type carburetor, both as used on BMW Airhead motorcycles, come in several varieties. In general, TWO present-day available versions will fit all the Airheads carburetors. Very early carburetors had a solid metal needle. That needle was available in more than one 'style', but for all, there was NO rubber tip nor a Viton tip, tip was simply part of the float needle. The later type of needle, that most of Airhead owners have, is similar to the photograph below. The needle shown in this photograph has a spring loaded plunger with a hole in it, with the easy-to-lose wire clip, and RED tip material. GRAY-BLACK tipped material will also be seen. I suggest purchasing the stock type needles from your BMW parts supplier, and not Bing themselves.

The all-metal needle used on early models is a different size, and will not properly fit later carburetors, and, vice-versa. Be sure to get the correct needle. If you want to install a Viton-tipped needle in a carburetor that used the Bing all-metal needle, you can, per Bud Provin (TheNickwackettGarage.com), who says to use the very common float needle used on many old Amal carburetors, as used on old British bikes. The part can be found on a simple internet search, for float needle 622/197; or, as 013, 622/197.

Bing float needle late style

What follows in this article is extensive information on the various floats; and, also some information on  gasoline problems, and a brief bit on storing gasoline. 

This article INCLUDES detailed reports of testing that went on for many years, specifically from 2003 to 2015.  

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