The forks appear to be mechanically very similiar on both bikes. However the 1JK model has
air valves fitted to the fork caps. This allows the forks to be pressurised giving a level
of pre-load to the forks. Unfortunately these caps have a slightly different thread to
that on the 1XL model and so are not interchangeable.|
I have not measured the spring rates on the 1JK model but I would imagine that, inline with most Japanese specification bikes, they are of a lower rate than the 1XL model.