Only under extremely hard braking (back end floating or coming off the ground) I set my sag for 14mm free and 28mm with me on in full gear when i measured last.. The suspension feels great but i know I am bottoming out. would adding oil help to prevent this? The bike has not felt this good in a while so i hate to mess with it but i do nto want to bottom out the suspension either. BTW it is a 2005 zx6r with zx6rr forks with 20mm penske internals and oil at 110mm with 7.5wt oil.
I would venture that unless you need to use more braking, leave it alone. Have you tried less brakes, they only slow you down you know...
I accidentally tried this very same thing by mistakenly adding approximately 20mm of oil in each leg and ended up with an extremely unresponsive front end. Essentially the forks were approaching hydraulic lock in the bottom 20% of their travel and chattering as I approached full lean on the brakes. According to Traxxion ideally you're looking for 20mm unladen and 35 laden. Can you subtract preload until you get close to both these numbers? It's quite possible that it's just a single bump somewhere in one of your braking zones that's sucking up all that travel, and you're okay the rest of the time. Also don't forget to factor in stiction when measuring sag, it can account for close to 10mm on some forks.
i wouldn't run a tighter sag than that cuz you want the fork to be able to have travel for dips/rebound. i would go up slightly in spring rate rather than adding oil if the bottoming is really causing a problem for you.
You can add oil up to the maximum oil level (minimum air space) specified in your manual. It's supposed to affect only bottoming resistance at the last bit of travel. If they still bottom, the correct thing to do is get stiffer springs.
thanks for the response guys. I would only add a little oil at a time, say 5mm to start. i have the zip tie and it is always at the bottom of the fork leg when i get back off the track. I will double check the sag number tomorrow to make sure the springs have not gotten weaker over time. ill post up what i find. BTW does anyone know what rate springs i should have being about 190-195 in gear?
For your weight with that bike a good start would be a .95kg spring although some might prefer a 1.0 to go towards the stiff end of the scale. It's almost impossible to get a well damped fork that won't bottom excessively without the proper springs for your weight so get that sorted first.
Russ.....if you like the way the forks are working and the only issue is bottoming, add 2 cap fulls of oil to each fork or 1 WD40 cap full (similar volume). Problem solved.
I think i will be getting new springs. i measured the sag taking stiction into account and got 18mm free sag and 33mm with rider. the rider is fine but the free sag is a little high meaning softer springs. I am going to try the .95 and see how they work. thanks for the info guys. much appreciated. maybe the 20lbs i gained since buying the bike has something to do with it
+1 Adding oil will progressively add dampening to the end compression travel. It's a pain in the ass but when you get it right you'll be happy with the results. You don't want to run out of travel when your braking and turning in because if you hit a bump when you're out of travel you'll more then likely end up crashing. Be patient, take good notes, and do a search for suspension set up guides on this website.
Agreed! :up: also, try to get the total length of the fork fully extended( bottom) and mark your fork tube.
