I think my bike uses the 140mm measurement too.
I removed my forks for the oil change, but I did not remove the cartridge. I just drained the oil, filled the forks with kerosene and pumped the hell out of the rod. I changed the kerosene a few times and was surprized at how much shit came out of the tubes.
After the kero wash, I turned the tubes upside down and pumped the rod until all the kero was out of the forks and cartridges. That was 10k miles ago and I've had no problems with the forks.