The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: montmil on August 10, 2008, 12:12:00 PM
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Might someone explain the small, rubber "button" on the very top of the Bing carburetor chamber? What does it do or not do? Thanks in advance, Monte
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I believe it seals a hole in the top of the dome (of the "dome top" vs. "flat top" scenario).
What the hole is for, I do not know.
I am pretty sure the inside needs to be sealed from the atmosphere, though.
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First of all, that plug should be a metal disc, not rubber.
It is not uncommon for the original metal part to loosen up, the Bing Agency even has a shop charge for this repair.
If it comes loose, it doesn't seem to present a problem, as we have had a few posts here where riders had a loose plug, and finally got around to repairing it by using a small coin and some adhesive.
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First of all, that plug should be a metal disc, not rubber.
It's either rubber or a hard plastic. Sure not metal.
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OK, I'm going to try to answer my own question about the Bing plug. Is that kinda like talking to yourself? Grandpa said it was OK as long as you didn't start answering yourself... Uh, I'm answering!
Couple Sundays ago, a few of us airheads went for an early morning ride of just over 100 miles. Mostly went "the cowboy way". That's how we refer to Texas' Ranch Roads and Farm-to-Market back roads. No rush, mon!
We did have to giddy-up to about 60 mph on a highway leading to our nice country breakfast. This is where I noticed an anomaly in the R65s engine ops... After just a couple minutes at 60 mph, the engine revs would kinda drop off. I'd drop down to about 50 mph and the issue would resolve itself. Back up to 60 for a few minutes and it's repeating itself. Hum. My buds are rapidly disappearing over the horizon. I'm not gonna get any biscuits if I don't pony up and catch 'em.
So. A few day pass and while I'm messing with my oil pressure LED install -that's a whole other story- I removed the rather depleted RTV silicone that was slightly covering the Bing carb top plugs. Most of the old junk was not even adhering to the carb. Earlier, a local R90 guy told me that the silicone was a common "fix" for the carbs. So I used some black RTV and re-did the "fix".
This morning, I was out running errands on the bike and planned my circuit so that I would end up on our city's outside highway loop where I could test the new glue.
It worked! Ripped along at a blazing 60 mph well past the point where I had experienced the earlier power sag. Obviously, the caps really need to seal the carb chamber from the ambient atmosphere. Cheap fix. Happy camper here.
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That's a good thing to find out, that a loose plug will cause problems !
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It's still sad that you still can't get over 60 mph, though... [smiley=evil.gif]
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Yeah, I have to keep mine down to 60mph just to not attract attention... :(
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Do 60 on the freeway here in Feenix and youll quickly get runned over! The carb tops really need to be air tight. I just wonder if there is not a more permanent fix?
rich
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The repair, testing and parts manual that I got from the Bing Agency, doesn't show the metal plug not available by itself, looks like it's going to be a 'homemade part', if you want a metal replacement part.
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I think one could put just about anything on top that they want - a coin, a roundel of the appropriate size (I don't know of any), and do any additional sealing on the inside...
Do these dome-top carbs have a large spring between the top of the slide/diaphragm and the dome-top? The flats do not. (just curious)
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The 64 series / dome top carbs have a spring in there.
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It's still sad that you still can't get over 60 mph, though... [smiley=evil.gif]
Oh, it'll git well over 60 mph without breaking a sweat. And the Vapor digital speedo and tach accurately tell me how far over! It was simply the 60 mark that generated my original Bing Top question.
Justin, you little devil you.
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Glad you found the problem so quickly - it toom me a few months to come up with the same answer on my R75/6. The gap between the disk and the carb body was large enough for me to insert a fingernail. Gel epoxy has worked fine for me - although I was not very neat putting it on.
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Glad you found the problem so quickly - it toom me a few months to come up with the same answer on my R75/6. The gap between the disk and the carb body was large enough for me to insert a fingernail. Gel epoxy has worked fine for me - although I was not very neat putting it on.
I'm beginning to think about a couple shiny silver dimes as Bing koozies. ::) The scooter is really much better behaved now that I "filled in the gaps".