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Old 04-29-2013, 10:25 PM   #2
Boxer Metal
Mad Scientist
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Joined: Nov 2003
Location: Chico, California
Oddometer: 3,521
Originally Posted by jjwithers View Post

I just rebuilt a R75/5 from the ground up and added the Siebenrock piston/cyl kit that supposedly is a 20% increase in power. + Lightened flywheel.

My R75/5 carbs were a bit too worn and the choke was leaking a bit and i couldn't get a good idle.

I got a set of Very good condition 32mm carbs that were from a R80GS. I took them apart and cleaned just a wee bit of crud out.

While they are apart, I'm wondering if I should leave the jetting and needle positions the same?

Or should I put the R75 idle/needle/main's in the new carbs?

The bike will supposedly be close to a R90 in power due to the piston kit but I'm not sure how the jets will effect or help/hurt the bike.
Ultimately, i want something reliable.

Does anybody have the Bing guide for jetting?

Thanks in advance.

Replace the following;

Slide needles BMW #13 11 1 337 692
#266 slide needle jets BMW #13 11 1 261 702
#45 idle jets BMW #13 11 1 336 924
#135 main jets BMW #13 11 1 256 612

That should be a great starting point if not spot on.
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