rebuilding sum carbs

Bruce Frey · Post by **Bruce Frey** » Sun Mar 04, 2007 3:32 am

I suggest that you contact Eckard Sieg.

Sieg-Neustadt@t-online.de
+49 (5072) 1740

Eckard is a carb specialist who attends both Veteram events. I have bought rebuilt carbs from him in the past. He speaks good English.

There is another carb specialist who came on the scene a couple of years ago that I have no experience with.
If you look on Ebay.de you may fime some repops of his. He does business under the name of phonograaf (or something similar)
Martin Schumann
Kla_Mot_Te@yahoo.de

Good luck,

Bruce

Darryl.Richman · Post by **Darryl.Richman** » Sun Mar 04, 2007 7:54 am

The slide in my Sum was quite loose and rattly, too. It wasn't possible to set the idle this way below about 1200-1400 rpm, or it would stall out.

The slide is quite simple, and I had a new one turned on a lathe from brass stock. It's much heavier than the aluminum original, but it seemed to work well. (The bike was only run like this a few times and then completely torn down for a restoration.)

Fortunately, my carb body, though worn, was not far out of round.

Barry Robin · Post by **Barry Robin** » Sun Mar 04, 2007 9:22 am

two very good places to start- thanks bruce! and even if he says no, he'll know who to ask...

darryl-your slide was aluminum? i still have my original 1931 in there-and it's made of bronze! heavy little sucker, that.
-b

Darryl.Richman · Post by **Darryl.Richman** » Sun Mar 04, 2007 9:39 am

Yes, mine was aluminum:

Barry Robin · Post by **Barry Robin** » Sun Mar 04, 2007 10:28 am

my, darryl, that's a lot of parts you have there-i may assume they're all now together.
funny to compare your R12 carb against my R11; the earlier ones like mine have the float bowl top in bronze, as is the end cap to the slide housing-and mine isn't a plate with screws...it's one big bronze screw cap that's threaded onto the (threaded ) housing. all very plumbing fixture in approach.

i see that your float tickler is still there; mine fell apart a few months ago and needs to be replaced-know anybody who has a spare one for sale?
-b

bmwmyplace · Post by **bmwmyplace** » Mon Mar 05, 2007 6:01 pm

Hey Darryl those little "eared" covers for the air cleaner , have you seen them for sale any where.....if not I will have to make them as I only have one

Regards Peter

Darryl.Richman · Post by **Darryl.Richman** » Mon Mar 05, 2007 8:47 pm

Sorry Peter, I haven't seen them for sale separately. I bought the whole repop unit from Blue Moon 5 or 6 years ago. Maybe 7.

Barry Robin · Post by **Barry Robin** » Mon Mar 05, 2007 9:41 pm

peter, you might want to try vintage imports in new jersey-they usually have them.
they also pop up on german ebay often enough...

-b

VBMWMO · Post by **VBMWMO** » Mon Feb 15, 2010 2:51 pm

hello all-
is there anyone who can still rebuild sum carbs for the R11/12? the slide on mine is so loose that it needs to be resleeved.(and it wouldn't hurt to have it gone over in general)...
i'm located in ireland but can post it anywhere.

i had heard that there are a couple people who can do it blindfolded, have parts-and can diagnose it too! hans raadstak is one, i believe-but i can seem to get ahold of him...(hans? you still out there?)

fourteen thousand sum carbs out there and no body's fixing them anymore, not even vech?!

sheesh!

Vintage BMW Motorcycle Owners