Reader of Aprilia Rs 125 Tuning Paul emailed to ask this question:

Hi John

I’m having a bit of a problem with my forks if i go over a bump or pot hole in the road i can here a clunking noise coming from the forks sounds as though they are bottoming out but not sure would you have any ideas

Thanks

Paul

I told him that I didn’t know the answer, but I would ask around. It appears that this problem is caused by the headstock, but the problem might be caused by the brake caliper being loose. First check that the rubber bushes on the brake caliper are in good condition and that there is minimal play in the caliper.

If you are confident that the problem is not being caused by the caliper, check if the headstock bearings and top yoke nut are tight. The stem and yoke bearings might need replaced, but the problem could also be caused if the stem threads on the top yoke are damaged. If the threads are damaged, it would cause the top yoke nut to come loose, even after being tightened.