fork bottoms easily...

86 VFR 700.

The fork bottoms very easy. Especially when braking. The anti dive doesn't seem to have nearly the effect it did on my VF500. I was going to change the oil in it with plain ATF. Before I do is this normal or a sign of worn fluid? Can I just drain and refill without dissasembling the forks?

 

Yea you most likely need to change the fork oil. If you change the fork oil you might want to think about changing the seals as well. I have never done a 84 before but I increased the viscosity for my 02 to decrease dive. I went from a 5wt to 7wt, all I had to do is take the forks off the bike and remove the cap at the top and drain the oil. Make sure you keep an eye on how much came out, because you will want to put the same amount back in . There are several youtube videos that go through the process, hopefully this helps a little bit. I know that my brothers sv1000 fork oil was so bad that it would feel like he had a flat tire, the once clear oil was brown when it came out. The bike only had about 18k miles on it.

 

First, you'll need to firmly support the bike before removing fork caps.

Measure the length of the springs, and compare with new specs. Sagged too short needs replacing. If replacing, i've had good results with Progressive brand springs on VFRs.

Yes, you should try flushing and replacing fork fluid, using fork-specific (not ATF) 10wt oil. You can either use volume measure (cc's) when adding new fluid or height measurement (6" below top of fork with springs out and forks compressed. Best practice is to remove forks from bike and wash out after disassembly, and fresh, clean fluid should improve the anti-dive action as well as damping.

 

Do you use any air pressure in the forks? Having a couple PSI in each leg may eliminate the bottoming.

 

You can increase the effect of the "air spring" by adding a bit more fluid too. Try 10cc's at a time.