fork damping problem

[Guest]

hi stripped cleaned rebushed and sealed the front forks on my sei refilled with 345cc of dexron refitted the forks way to soft measured the viscosity of dexron around 7-8w. flushed them out again and refilled with 20w motul fork oil went for a ride all good now done around 600 miles and the damping seems to be too soft again topping out over speed bumps my first throught was that valve must be stuck so drained the oil seemed very thin when i checked against what was left in the bottle there is a big difference the roads around here are bumpy and me and the wife are no lightweights so oil takes a pounding but 600 miles any one else had this happen? I am going to try different brand of oil any suggestions?

[Oldman]

PJ1 Fork Oil. I don’t use ATF in my bike, I’d rather just use fork oil, and I can get PJ1 20 wt. from the guy down the road. Never had a problem with it. Are you using any air pressure in the forks? Maybe try increasing it to the max, 6 lbs., and see if that helps.

[Guest]

cheers i can get pj1 down the road i've been running 14psi and have no problems on compression of the forks just on rebound a lack of damping been looking at the anti dive that even on max seems weak so will change the oil and will give it another try can you refill oil through the air connection save struggling with the springs again!!?

[motor22]

I just switched to ATF and I run 12-14lbs front 65-75lbs rear and love it. It is a slightly harder ride but I get minimal dive and she handles great. It does sit higher but that gives more lean room for the twisties. jmho

[Ed Z]

Possibly what is happening is the oil is getting aerated (lack of anti-foaming agents) thus causing it to become less viscous... I don't recall the volume of oil, but 345 oz seems a bit low (will need to check on that one)... Also, did you bleed the air out of the forks prior to putting the spring back in.??? What I do is to add the new oil and then compress and extend the fork several times (slowly) until dampening is consistent over full travel... This insures all air is bled out of the damper... Then reinstall the spring and end cap...

[Guest]

thanks for your input guys got the 345ml from the cymer manual. Today the bike had stood for a couple of days and also colder this morning and wasn't so bad, so poss foaming/ bad oil, I won't be using Motul again. got some 20w pj1 to go in tomorrow will see how that goes. Off camping with trailer next week so good test thanks again for your input, cheers Paul

[Ed Z]

Just be sure to bleed the air as described above...

[Guest]

change the fork oil on saturday it came out full of air and runny , I went for a good run before. I think I have found the problem, earlier I noticed that the boots on the anti dive units had perished so ordered some more, on back order arrived last week so fitted them when the oil was out, removed the phillips scerws in bottom to clean them and found one side had spring and ball in other did not these look like a valve so only one side working properly and over working the oil the other side just whipping it full of air? anyway I use the bike for work everyday so had to go back together vast improvement with new oil just hope the ball and spring arrive before we go on holiday.