Bing rebuild + tuning. Choke problem.

[clouseau]

Hello,
I'm new to the forum and the R65 for that matter.  When I purchased the bike, it was running great.  I never had to use the choke.  The guy I bought it from told me I didn't have to.  But shortly after the purchase, fuel began leaking from the right carb.  So I decided to rebuild them.  They weren't in that bad of shape at all except for the slide needles which were badly corroded and the slide needle shaft had tons of gunk in them.

Now since the rebuild, I can't get the bike to cold start w/o holding the throttle open and the chokes are absolutely pointless.  They don't help and the plates are not on backwards (I triple checked).  I balanced/tuned them with the Twinmax and the bike runs smooth with no power loss through the entire powerband, but every once in a while it will die at a stop after being well warmed up.

I spoke with Bing about the round plastic cap about the size of a dime on the top of the carbs.  Mine are loose and visibly rattle when running and Bing said they definitely need to be sealed or they will suck in air, so that is next on my list.

Any ideas on the cold start/choke situation?  I've double checked to plugs and they are both a light brown color.

Thanks!
Joel

[Bob_Roller]

First off, welcome to the forum!!

Sounds like you are new to BMW bikes, normal starting technique is fuel on at the fuel tap, full 'choke', no throttle input until the fires and 'catches' .

I would have to go with possibly of a clog somewhere in the 'choke' system.

Not knowing your mechanical expertise, I'll have to start basic, any chance that the 'choke' assemblies got swapped between carbs, they are side specific.

You didn't mention what year your bike is, so there's differences between the '78-'80 models, and the '81 and later models.

When the 'choke' lever is moved, do both arms on the carbs move as well ?

Are the 'choke' cables adjusted correctly, on the '81 and later bikes there is a cable 'splitter' under the tank, possibly a cable has become dislodged in there.

How far did you take the carbs apart ?

[nhmaf]

Welcome aboard !

Chances are very good that we can help you solve the problems - or at least not make it any worse !
 

First, you'll really have to solve the top cap sealing issue first before you go any further as leaks there can basically throw many things out of wack.   Once those are sealed airtight, you should go back over the carb adjustments and synching, etc.  But first, some more questions:

With your "carb rebuild" - did you take the bowls off and clean them out with carb cleaner and were able to blow air through the enricher circuit/jet?  The enricher circuit fuel pickup is in the bottom of a corner of the bowl, and there is a brass tube/jet inside the "web" of the bowl - see this thread here for description and pic:

http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1240083062

Please let us know the model year of the bike (or the engine, if it is a transplant).  Also, there are some numbers on the body of the carb on the inner side like "64/32/303" or similar, which can help us determine proper setup.  Lastly, does this bike have a "stock" exhaust system, or an aftermarket 'performance' type exhaust?

[clouseau]

Thanks for all of the replies so far!

1982 R65LS 46,000 miles.
64/32/325-326

I marked the choke plates during breakdown.  I'm 99% sure they are in with the correct carb.  I made sure to adjust the same amount of slack for both choke cables and they seem to be moving in unison.  However, if I move the handlebars from left to right with the choke full on, it will retract. Binding?  All springs have been replaced.

**Interesting note**
After the rebuild, I took it to a BMW guru to have him tune/sync it.  He did it all by ear.  But it didn't run or idle correctly afterwords.  After some inspection, I noticed the right choke sticks halfway open.  He didn't notice. Some guru. That's when I bought a Twinmax and did it myself.  Even with new choke return springs and additional dis-assembly, the choke would not return on the right carb, so I just loosened the nut just enough to allow full movement and used locktight on the nut.
***

I used carb cleaner (Berryman) and blew out every orifice and then followed with compressed air from a can and made sure air was flowing through them.
It was almost a complete disassemble save for the butterfly valves. I didn't want to get involved with that and they still felt fine.
Yes, the bike has aftermarket exhaust but there are no markings of any kind on them, so I can't tell the brand.  They are louder with larger outlets than the stock.

Finally, another thing the guru did was remove the fuel filter stating that he never uses them and there is one in the tank anyway.  I went with it for a couple of weeks, but something told me to get one.  Well, this bike has been repainted to silver from red and there were specs of red in the old filter.  Almost immediately with the new filter I can saw a few red flakes.  So no filter in the tank, I can safely assume, and probably some flakes floating around in the float bowls.  

I'm half tempted to disassemble again.  But first, sealing those caps.

Thanks again for all the help!
Joel

[montmil]

The red flakes you are seeing are probably bits of the original fuel tank's "liner" as it disintegrates. Inline filters are a really good idea on these vintage scooters.

You may have an interior hang-up within the right side "enrichener". There really is no choke on the carb but an enrichening system that is like a small carburetor.

Remove the carb and disassemble the offending "choke" components. The ghetto fix of loosening and gluing the nut won't get the carb working correctly. You should see a small "pip" on the end of the enrichener shaft. Also, the teardrop-shaped opening in the carb disc should be "up" in relation to the top of the carb body. When the interior disc is correctly installed, this indented mark will be adjacent the "bump" in the disc housing. Clear? Go look...

Also check the choke cable for length and the adjuster end on the carb body.

Black silicone adhesive works well to seal the loose carb top "caps".

Post back with your findings.

Monte

[vestandpants]

used this site when I overhauled mine years back:

http://www.gunsmoke.com/motorcycling/r100gs/carb_rebuild/index.html

[nhmaf]

And, the 82 LS has the oft-hated "cable distributors" or splitters, on both the throttle and choke cables (splits the (1) cable that connects to the throttle or choke lever into (2), and these are located under the fuel tank.).
This is another possible source/location for cable binding or having a bent/frayed end hanging up inside the housing of the cable splitter, which is a bit like building a ship in a bottle to take apart and put together again, but with patience it is do-able..  It might not be the cause of your sticking choke arm on the carb, but it is another item to add to the list of possible culprits.

If you don't already have one, the Cymer Manual for these BMW airheads has a pretty good section on dis-assembling and reassembling the carbs with lots of pics.

[Lucky_Lou]

Hello and welcome
If the carbs have a plastic plug on the top it makes 81 on, there is a spring under the top body check its in one piece as its quite fine they have beeen known to fail Pre 81 have no plug or spring my brothers bike a 81 r65 used to start without choke till he replaced the very worn needles then he found the enricher jets in the carb bowls were blocked sounds like a simular problem to yours.
Lou
ps the gunsmoke link is very good

[clouseau]

OK, thanks so much for all of the input.

 I am going to seal the tops and take them apart again and blow out again.  I know some tank debris got through.  I am also going to check for binding in the cabling.  FYI, the right choke/enricher return is not cable related as it binds up when cable disconnected.  

A question that may be related to the cabling...
Don't the LS models have shorter & lower handlebars?  If so, I am 99% positive I have non-LS handlebars and wouldn't that affect the cabling concerning length?

I will get back with the results!

[nhmaf]

clousseau -

The US-market R65LS models came with fairly high&wide bars, as that is what the marketing guys figured that we wanted, even on a cafe-style of bike - pretty dumb, but anyhow - if your bars have about 4.5" of rise and pullback and are quite wide, then they are stock US market bars.  The euro/Canada bikes came with the low narrow bars.   I had the US bars on my bike, but as I am tall (6'2") I felt like I was riding a kid's tricycle with those bars on this bike, and couldn't lean forward into the wind.  I bought some new euro bars and ended up giving my old bars to another guy on this forum who had the short bars but needed the long ones because of a back condition.

If you change bars, you will have to change the upper brake line and likely the clutch cable.   Depending on if you put the euro bars on or another type of bar that isn't quite as low/narrow, you might get away without having to change the upper throttle cable (from throttle to splitter) and the upper choke cable (choke lever to splitter), but I had to do so with the LS euro bars.

[montmil]

used this site when I overhauled mine years back:

http://www.gunsmoke.com/motorcycling/r100gs/carb_rebuild/index.html

Joel, Do you have either/or both BMW manuals? Clymer and Haynes both have good photo-documented disassembly and rebuilds of the Bing CV carbs.

Gunsmoke good! We like pictures.

Here's a couple others that I have downloaded to my personal Neo-Clymer:

http://www.largiader.com/tech/carbs/
http://www.ibmwr.org/r-tech/airheads/carb_rebuild.shtml

For the insomniacs among us, there's always Snowbums tomes.  

Monte

[clouseau]

Yep, I acquired the Clymer before the rebuild as well as all of these online articles posted. I really tried to do my homework before I defiled a perfectly good running/starting bike.

Thanks for the handlebar info nhmaf!  It just seems that every LS I see has the cafe style bars and mine doesn't, but I like the feel of mine just fine.

BTW, here's the condition of the slide needles before rebuild.

[montmil]

Now that's nasty looking! My jet needles were worn pretty well but were still their original color.

[trolle]

Can't keep wondering about the sturdiness of our bikes. Seeing something like the above, I wonder if I am getting anal when I am hunting for something to renovate, adjust or exchange to get that tiny fraction of extra power or better sound.

greetings from a grey morning in the north

[Justin B.]

The ones in the carbs in my '81 R100 looked just about like that.  I'm almost ashamed to say that I chucked them up in a drill and cleaned them with a Scotch-Brite and used 'em!  They were slightly pitted but they appear to work fine as I get over 40 mpg and it runs like a champ.  I did order new needles (which I have) and will replace them someday, probably when I replace the jets...