@6by9: I know, I clearly stated B+ V1.2
@joan: As I said, at least with bmp085, I've don't know for other modules. The bmp085 is at 3.3V, no risk here. I love the word benign...

Thats what I did. Thank you guys, great forum. So, to summarize for future people having this issue: If you're on a B+ V1.2, Raspian, Kernel 4.4 and want to enable the second i2c-bus, the i2c0 or i2c-0, because you want to use two bmp085 or bmp180 and won't try the XCLR trick, you've to do the follo...

Ok, tried that: pi@raspberrypi:~ $ sudo raspi-gpio get BANK0 (GPIO 0 to 27): GPIO 00: level=1 fsel=4 alt=0 func=SDA0 GPIO 01: level=1 fsel=4 alt=0 func=SCL0 GPIO 02: level=1 fsel=4 alt=0 func=SDA1 GPIO 03: level=1 fsel=4 alt=0 func=SCL1 GPIO 04: level=0 fsel=0 alt= func=INPUT GPIO 05: level=1 fsel=0...

@Massi: I'm aware of that.

So I tried again, rewired everything correctly, with the pullups in the correct place.

Without success.

On "i2cdetect -y 1" I get my 77, but not on "i2cdetect -y 0".

A gpio readall gives me ALT0 for pins 27&28. Is that a good sign?

So what you guys want me to do is this:
@Massi: I do not want to do that XCLR trick, results seem to be rather mixed and slow... But thanks for the pullup heads up...
@joan: I already added pi to i2c, just didn't think about...

Sorry to dig this out again... I'm on a B+ and want to read from two BMP085 barometric sensors. After reading this whole thing and a lot of tuts I added "dtparam=i2c_vc=on" to config.txt and ensured "i2c-dev" is in /etc/modules. When I wire the bmp085 to i2c1 I get the correct "sudo i2cdetect -y 1" ...