KYB Fork Spring Rate Change

I have a 95 KX250 with 43mm diameter KYB forks. I am looking to increase the spring rate but I am finding that only .38kg/mm and .40kg/mm rated are available off the shelf. I need a spring rate of 0.50kg/mm. Has anyone ever tried this on these forks?

I talked to a custom spring shop about fabricating a spring with this rate. They were going to hold the O.D of the spring the same and let the extra wire diameter be on the I.D. of the spring so the spring won't rub the outer fork tube. The problem with this idea is that the steel stamped spring guide will no longer fit. I am also concerned that the plastic cartridge will now rub in the spring I.D.

If any body has experience with this upgrade, please chime in.

Just in case someone else may benefit from this topic, I will provide an update. I ordered a set of customs fork springs from Cannon Race Craft. They were able to hold the I.D. to match the OEM spring so all of the fork's internals can still be used. There was enough clearance on the outside to let the extra spring coil thickness to fall there. I have the new springs mounted, but I havent't ridden them yet. I plan to inspect the springs after a couple of rides to make sure they are not rubbing the inside if the fork tube while riding.

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