3 replies [Last post]
dBDawg's picture
VBMWMO #8575
Joined: 01/18/2013
Posts: 53

I'm rebuilding this carb and was wondering what I should buy for jets. There are a couple different sizes I'm not sure where to start. The only thing I can guess is that I may need the 35mm because the old ones are approximately that long. Just not sure what I don't know and if they should all be the same or a combination of sizes. Thanks

  • bmw_r11_-_carb_-_14.jpg
Darryl.Richman's picture
VBMWMO #6285
Surf City, USA (Santa Cruz, CA)
Joined: 10/27/2006
Posts: 2185
Jet sizes

The parts book lists all of the jet sizes:

Position    Default Size   Alternate Size
idle        35             40
transition  65             --
main        70             75, 80

These positions are from left to right, as seen from behind the carb.

If you can't get new jets, you can try to fix your worn, oversize jets by buying a fine drill set, finding the right diameter bit, and then soldering around it while it's inserted into the jet tip. The sizes above are in 100ths of a mm. There are gas jet drill bit sets that cover these sizes.


VBMWMO Webmaster,--Darryl Richman

dBDawg's picture
VBMWMO #8575
Joined: 01/18/2013
Posts: 53
Thanks a bunch, Darryl. I

Thanks a bunch, Darryl. I wasn't getting that out of the manual I have, but I am at the mercy of google translate. And I guess I just have to laugh at my inexperience with the sizing designation, but now I know.

Thanks again

Ian R11
Ian R11's picture
VBMWMO #8148
Yorkshire uk
Joined: 10/22/2011
Posts: 202
Saying what works for one of

Saying what works for one of these carbs may not work the same in another, I have two carb bodies and get different results with the same jets swapped from one to the other.

Also the fuel available to you makes a difference, locally we have 5 to 10 percent ethanol and found the larger of the jet sizes available work best. I eventually used a combination of old and new and have jets measuring .45, .65, .8 fitted. Ideally a set of jet reamers with .05mm increments would be useful for setting up these carbs if you can find some, I never did.

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