Just tried a kxf 14 chain slider on a kx250 91 swingarm ,which would be closer to a 87 than a f model, no holes match ,than I tried a 05 to 08 kx 250 2t it was closer, you would make the 2 back holes work by drilling and tapping new threads ,than again the 91 could be different from the 87 ,I have seen a guy use a plastic cutting board on a late kx f , because they eat chain sliders and guides for breaky even the tm stuff is a lot better, but I seen them gone in 50 hrs . Kawi has the angles in a way that eats them up? Plus the material is too soft.