Should BING carbs have holes in the top?

[Tony_Pattison]

hi, just bought a 1982 R65. Rode it 95 miles home and had no problems.

I noted, once safely home, that the left hand side carb didn't have a BMW sticker on the top of the dome part, while the right hand one did. The very top and centre of the left carb looked like someone's been working on it, so I peeled off the BMW sticker/label  on the right hand carb, just to see what the left hand one should look like. This is how I found that beneath the BMW label/sticker there was a hole. This hole (on the right hand carb) is about 1cm in diameter and looks to go into the vacuum chamber. It has no thread on it, but looks like it was manufactured that way.

So, is this how the carb (right hand) is meant to be? If so, why doesn't the left hand carb have a similar hole. And surely, there needs to be a vacuum  under the dome part, so should there be an insert in the right hand carb, to fill the hole (rather than having a small BMW badge stuck there).

thanks in advance

Tony

hopefully, you can see pictures of what I mean by going here and looking in the album :- http://photos.yahoo.com/tony_pattison  

[seniorchiefSS]

I have owned 4 airheads. all with Bing carbs. none of them had the hole you show. the top of the carb has a factory seal cap on it that should never be removed to my knowledge. maybe the po popped it off and took the cheap way out to fix it. but only the person who put the sticker on can tell.

[Rob Valdez 79 R65]

It looks like there was once a factory plug in there, but was removed for some unknown reason...

Plug it up, or get a replacement cap.  Should be cheap from someone's pile of carb parts.

[Ed Miller]

Good grief, the factory cap is indeed missing.  The Bing agency will replace them, though I don't remember how much it costs.  Probably less than the price of putting a kid through college.  The carbs need it.  I guess they are sort of peened in, maybe with a custom made anvil.  

Good luck,

[thrang]

I'd repalce the carb dome, they are not much s/h, but since they are only about £25 ($50ish) new from Motobins I'd just buy a new one.

[Justin B.]

Being a cheapskate I would probably grind down a low denomination coin and JB-Weld it in place.  Maybe do both and use a couple of those new buffalo nickles - that would look unusual!    Cost?  $.05 plus a couple bucks for the JB-Weld, which everybody should have anyway...

[Tony_Pattison]

thank you all for your responses.

Justin B you're a man after my own heart. Turns out that a UK 1p piece is an almost exact fit, so I thought I'd epoxy one over the hole. And put one on the other carb for decoration (one heads one tails).

I'll probably leave the replacement top fitting to my list of winter jobs.

thanks again

Tony

[Baffo]

I epoxy'd mine all over after finding out they moved around and were the cause of stuttering etc
.

[Tony_Pattison]

thanks again to everyone who replied.

I've epoxied a UK Penny over the hole, and a 1982 (year of first registration) Penny on the left carb (to match).

Must admit that I haven't noticed a lot of difference in the engine performance. Still pops a bit on the right side in overrun.

New pictures here:- http://photos.yahoo.com/tony_pattison

have fun
Tony

[Ed Miller]

A guy named Lance, at the tech session at Chief Joseph, said that there was another seal beneath that cap, so that the diaphragm isn't exposed to atmosphere even if that top cap is missing.  I was surprised, but he seemed impressively knowledgeable as far as I could tell.

[Tony_Pattison]

Ed,
that would make sense, as I noticed no difference after having sealed the hole with an epoxied penny. And that I rode the bike (complete with hole) over 90 miles at a constatnt 60-65 mph.

thanks
Tony