Bing 64/32/11&12

[Al_C]

The flat top 32mm Bings on my 78’ R65 need a full overhaul but I have a set of Bing 64/32/11&12, if I jet them the same as the flat tops any reason why they wouldn’t work on my R65?

Thanks in advance

[Barry]

Welcome

No reason at all in principle why dome top Bings wouldn't work on your 78.

The idle jets would be the same size anyway and the mains. The only practical difference between the two types of carb is the arrangement for guiding and lifting the slide so there's a chance you might need to experiment with the needle position but I'd start with the same position on both carbs. 

Beware of copying jetting from later R65 81-85 model carbs because the very different intake system resulted in changes to the jetting.

I'll be interested to hear how you get on.

[Al_C]

Thanks for the informative and quick reply Barry.

I have a long journey ahead of me with this one.
I got it running, just but it’s a bit of a barn find and requires a lot of service/consumable items as you would expect.

[georgesgiralt]

Hello,
The most important thing in a carburetor is the diameter of the passage. I bet it is the same on both models ;-)
Then comes the piston various cuts but I bet this make that much of a difference on a beaten old BMW engine... If they are different.
So if you install the same jetting as the previous carbs, you'll be good to go, maybe not the best gas mileage, but ....
Keep in mind that the needle position may need to be altered for the bike to pull properly.
Have fun !
P.S. : I, for one, would remove this huge fairing which is a big air resistance... But maybe you bought the bike for it ?

[Al_C]

Thank you for your reply!

I am totally with you on the the fairing, first thing I removed, took me ages to get that and all the associated brackets off!  It revealed a lovely slim rust free machine underneath👌🏻
Next to come off were the panniers which a previous owner had decided to colour code, great paint match but poorly executed.

After getting it running albeit poorly I am now in the process of going through it front to back touching every part and overhaul where necessary.  Next step will be to get it to pass my countries fit for road test(MoT) then to decide on what’s next.  I think the bike has been painted at some point including the frame as it is so rust free, unusual for something this age where I live so it’s not a 100% original bike.
Also to do the bike some justice it deserves and engine refresh but that may need to be next winter if I keep it.

[georgesgiralt]

Good.
Start with a full fluid change (include the forks. you'll be surprised what you find there...) and pay a thorough attention to the brakes.  The hoses may be factory original from 1978....  Do not forget to grease the bearings in the wheels, swinging arm, and steering.
Then ride it and see how she goes. Then decide what .....
As per the panniers, if they are from BMW, they pop up often on the second hand market for not that much...
Welcome to the Club !!!

[Barry]

Thank you for your reply!

 I think the bike has been painted at some point including the frame as it is so rust free, unusual for something this age where I live so it’s not a 100% original bike.

At first I thought your bike was the original silver beige colour which is a correct option for that year.  The lack of pinstripes on the tank and what looks to be a slightly darker shade than the original silver beige suggests it has been re-painted.  The front fork legs would have been bare alloy rather than black.

[Al_C]

Rock n Roll Friday night.
One down one to go.

[georgesgiralt]

May I suggest that you renew at least the needle jet, the needle and the rubber ? That would make your mileage way better and the bike more responsive.
Depending on the body exact situation, the rubber on the axe may need replacing, also.

[Al_C]

May I suggest that you renew at least the needle jet, the needle and the rubber ? That would make your mileage way better and the bike more responsive.
Depending on the body exact situation, the rubber on the axe may need replacing, also.

All rubbers and gaskets replaced.  I haven’t changed the the needle jet as yet but watch this space

[georgesgiralt]

Perfect !
The needle vibrate into the needle jet and wear it off. When you get the new needle and new jet, check the play the new needle has in the old jet and vice/versa...