Front fork oil

10W-40 engine oil or medium weight fork oil, 180cc instead of 150cc will do the trick. Atf is way to thin.

I'm attaching a snapshot from the Rider's Manual -- the factory was pretty nonchalant about fork oil grades.

Don't forget that experimenting with fork oil quantities is also experimenting with your secondary air springs ...

Previously ashley_cutler wrote:

10W-40 engine oil or medium weight fork oil, 180cc instead of 150cc will do the trick. Atf is way to thin.

See service release N3/12 suggests 180cc of oil, if I remember correctly, I have used this on MK3 with medium weight fork oil and a 13mm front brake conversion and ride on the A34/M3 Winnal interchange during rush hours with the rest of the idiots, yes, I am over 15 stone so the front brake takes some abuse and still does not bottom out.

Similar on my 850 MK3,with 13mm conversion master cylinder, BUT WITH AN OIL FORK grade 20 and in duet with luggage it works very well if all the elements of the fork are in good condition of course.

it makes a loud "clack" noise when I put it one the centrestand and the front forks extend to max

That is caused by a design flaw introduced when they drew up the forks and forgot about the anti top out, this is created by the oil trapped between the top and bottom bushes after the top bush covers the holes in the stanchion. The damper rod is too short and the damper valve reaches the top of the damper rod before the holes are covered.

2 fixes

1. Fit longer damper rods, this increases the travel of the forks at the expense of allowing the bushes to get too close to each other and the excessive clearances ,compared to modern forks plus wear, then allowing the legs to jam. With more work with relocated holes in the stanchions you can correct this by getting the hydraulic bump stop to work earlier but way too much work.

2. Fit longer top bushes, if they are the right length then you lose very little fork travel and you lose the clunk.

I agree with John, though that loud clack is a sure sign that the damper top hat nuts/bushes are beginning wear and will eventually allow the oil to bypass the new hydraulic bump stop.

If you do all the mods while the forks are in bits replace those top hats with a pair made of cast iron from RGM they don't wear out as quickly.

I use semi synthetic ATF D111 and all the mods above plus the RGM alloy damper body.

Regards,

Dave

I have been using an rgm covenant fork kit for years. Combined with progressive springs and 15W proper fork oil it makes the world of difference. I have been known to watch the forks going up and down out of sheer pleasure, when safe to do so of course.