The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: beemer on August 12, 2009, 04:41:48 AM
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Iv'e noticed that in my Haynes manual it says to adjust the air screw, turn till closed, and unscrew 1/2 turn,most of what i see here are saying 3/4 open?is this for older bikes/carbs?mine is a 83 LS.
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The Clymer manual has a very nice section of charts regarding the various BMWs and their carburetors. Per this manual, the 1983 R65LS, with 32mm Bing CV carbs #64/32/335 and 336, should be, "Mixture adjust screw opening from full closed 3/4 turn out." No notations of differences between UK and US bikes.
Hope this helps you, Beemer. Monte
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The Clymer manual has a very nice section of charts regarding the various BMWs and their carburetors. Per this manual, the 1983 R65LS, with 32mm Bing CV carbs #64/32/335 and 336, should be, "Mixture adjust screw opening from full closed 3/4 turn out." No notations of differences between UK and US bikes.
Hope this helps you, Beemer. Monte
Strange how these manuals seem to vary!!!i set up my carbs with 1/2 out as in the Haynes manual and it's running fine,strange eh!!Julian.
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My carbs are running a bit rich, and I have a quick question to make sure I have things correct. Does turning the screw in lean the mixture?
k_enn
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Yes, turn them in to lean out the mixture, turn them out to enrichen the mixture .
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My carbs are running a bit rich, and I have a quick question to make sure I have things correct. Does turning the screw in lean the mixture? k_enn
Are you running rich at idle or further up the fuel circuit's food chain? Unless it's a rich idle concern with black-ish smoky exhaust and rough idle, the air mixture screw may not produce the adjustment tweaks needed.
If possible, go for a decent length ride and just before you get home, try to shift into neutral, kill the engine and coast into the garage. Plug reading time. The condition of the insulator will give you a good idea as to correct, or not so, fuel/air mixture. More info, please.
Monte
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It seems to be running a bit rich all the time. I can definitely smell it in the exhaust not just on start up, but also at the end of a ride. A secondary indication of richness is that it will not start (in any temperature condition) if the choke lever is opened much more than an eighth of an inch, and even once started will not run if the choke lever is opened more than an eigth of an inch. This secondarily indcates to me that the mixture is as rich as it can handle.
There is no heavy black smoke on start-up, but there is a moderate amount of lighter colored smoke for a few seconds after start up. Start up can be difficult at times -- it cranks and wants to catch but fires up with some difficulty. If I open the throttle more than a little bit (one quarter inch to three eights of an inch of movement), it will not fire up and ceases to ignite the fuel.
When warmed up, it idles at spec rpm, but there is a bit of roughness in the idle but it does not stall. Until warmed up, it will not idle on its own and the throttle must be tended to manually.
I rule out the choke being stuck, the cables moves freely to the point where the choke lever is as open as it will go.
Runs fine at riding speeds.
This is not a sudden condition, but one that has been gradually getting worse this season. While the starting has only gotten a little worse, the smell of a too rich exhaust and intolerance for virtually any choke use during any conditions has worsened noticeably
k_enn
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After reading your description of the operational problems, I'm going to suggest that the, "getting worse this season" issue just may be the enrichener (choke) itself. The enrichener circuit is actually a small carburetor within the Bing. Even has its own throttle cable. Owners have had problems related to the gasket and O-rings inside the choke's mechanicals that are similar to yours.
Unless you have a large buildup of silt in the needle/needle jet/atomizer circuitry -due to an air leak or faulty air filter- I would not think the idle air circuit is the culprit. The gasket and O-ring parts are quite economical and the service is simple although you do need to remove the carburetors.
That's my $0.02 worth. Anyone else have a fault diagnosis, please chime in. K_enn needs to ride [smiley=thumbup.gif]
Monte
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I'm going to defer to my elders opinion, however I did learn a nifty little trick this past weekend that had plumb eluded me before.
With the engine at idle pull up on the throttle cable of each carb one at a time and see what it does. If the rpm increases then it's probably OK, if the rpm revs, then slowly falls off then you may have a diaphragm issue. If it doesn't rev at all or dies you definitely have a diaphragm issue. I didn't see where you have changed the diaphragms.
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The 1/2 turn out on the mixture screw is basically to get one in the ballpark - as we say. BMW tweaked with the jet sizes and jet needle positions on all the carbs on each model over the years, and your results may vary a bit. I think that mine are somewhere between 1/2 and 2/3 turn out on my 82
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Thanks for the help guys.
One additional point I did not mention in my earlier post -- once the bike is started and running for about a minute, it will start right up without any problem. If it has been ridden until it is up to normal operating temperature and then I stop, it wil start easily (for up to several hours after I stopped). After a few hours, it gets hard to start again.
Before I tear into the carbs, can anyone point me to an exploded diagram of the carbs? Thanks.
k_enn
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Well, we've totally hijacked Beemer's original thread even if the tangent is related. :-[
The link is from the Bing website. I'm still betting it's a problem within the enrichment circuitry and hardware. Monte
http://bingcarburetor.com/pdf/MOTORCYCLE%20CV%20EXPLODED%20VIEW.pdf
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Well, we've totally hijacked Beemer's original thread even if the tangent is related. :-[
The link is from the Bing website. I'm still betting it's a problem within the enrichment circuitry and hardware. Monte
http://bingcarburetor.com/pdf/MOTORCYCLE%20CV%20EXPLODED%20VIEW.pdf
I will forgive you Monte! ;)
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It seems to be running a bit rich all the time. I can definitely smell it in the exhaust not just on start up, but also at the end of a ride.
k_enn
You have worn needles / main jets. Inspect the taper of the needles on a piece of glass pane and you will see where they have become grooved. My 2¢
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Another fairly simple check. Good call, Rich. Earlier Bing needles were brass and were susceptible to uneven wear patterns in a relatively short period of time. The new ones that came in my overhaul kit are steel.
This steel on brass -the needle jet is brass- could also create a wear issue for the jet. I'd be less prone to suspect a main jet as being worn out, as Rich offered, but they are inexpensive and simple to replace.
Monte X [smiley=2cents.gif]
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Phorqs,
Interesting diagnostic for carb diaphragm issues. I just performed the procedure and both sides rev'ed and stayed, but one side was definitely "smoother" running than the other. Note I just completed a minor tune up and sync'ed the carbs with a TwinMax. She runs great, but I've been suspicious of the carbs since they are all orig on my '79.http://www.bmwr65.org/htdocs/yabbfiles/Templates/Forum/default/undecided.gif
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Here on R65.org, it's been the Summer of Love Not Lost On Carbs problems and concerns. I imagine you've been lurking about before you actually enlisted but the Tech section threads have been full of Bing overhauling, tweaking, tuning and bashing.
If not for the mutual support and advice, we'd probably all be riding Hondas by now. ;D
PS: Jack, think your smiley emoticon got jacked.
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Jack reminded me of a procedure I learned for checking carb diaphrams: temporarily remove the tubes between the air box and the carbs (yeah, they're just held on by the other tube), start the bike, and have somebody blip the throttle up whilst you stand behind the bike where you can see both slides move up in unison. Or not.