2008 yz250 is the bike. I am a vet A rider doing mostly single track in the north east with some fast trails. I am 5'10" 195lbs without gear. What fork spring rate would you suggest. Currently running 4.4N with 4mm measured preload and 1.6kg ics springs my tuner suggested. I am thinking I should be at 4.6N or possibly just add a little preload to the 4.4 as they dive a little much under hard cornering and the front feels vague.
Unrelated question, I had drilled the free piston with 4 3mm holes but did not remove the upper o-ring seal. Should I remove the o-ring next time I rebuild the forks or leave it. Im thinking I should because it's still gonna build air pressure because the air cannot escape those holes under a fast movement of the piston. This could make a spike in dampening even if the piston doesn't break. Thoughts?
That's what i was thinking 4.6N as that is the rate I run in my wp closed chamber KTM 250xc forks. His reasoning was the 1.6 ics spring adds to the overall spring rate so you need one rate lighter with KYBs. The way I see it though the 17psi in the WP bladder does the same thing adding to the main spring rate so why would it be any different?
The ICS piston moves relatively slowly compared to the front wheel. The holes you have now are excessive to requirements. One would have been enough. Keep in mind that the original design had none. Removal of the upper o-ring will benefit by reducing drag more than anything else.