Happy to be corrected but I don’t think the forks do much in the way of affecting the ability of the suspension. Maybe a rebuild on the damper would yield better results or an aftermarket job, such as the Wilbers that were advertised on here, sadly I think they were for a GSA.
Do you know how the front suspension/steering on an 1100/1150/1200 actually works ? Go have a close look.
All the forks do on an 1100/1150 is attach the handlebars to the front wheel. Hence why there are no fork "upgrades".
If you fitted forks that operated in the same manner as a "normal" bike they'd be fighting against the bmw front shock.
There are bikes with the front telelever removed and upside down forks fitted but that requires an entirely new front subframe especially made, and believe me, i've ridden one, it's not an improvement on the bmw setup, it's a backward step. .
There are bikes with the front telelever removed and upside down forks fitted but that requires an entirely new front subframe especially made, and believe me, i've ridden one, it's not an improvement on the bmw setup, it's a backward step. .