[2bikebill]

There was a clunk when I pulled my bike onto the centre stand today. (G5, 10,000 miles). It seems to be coming from the top of the LH fork, and I can make it do it by rocking the bike back & forth on the centre stand. Seems to be when the fork bottoms out, but I can't make it do it when it's not on the stand, even through the fork's full travel, Bike seemed to be handling ok on the way home, just a short run into town.
Any thoughts?
Thanks,
Will

[barenekd]

How's the oil supply in the forks? It sound like one leg may be a bit low so it's not working the full distance in rebound (Extension).
You can put the bike on the center stand, pull the caps and check the level of oil in each fork. This is mainly to see if you have an even amount in each side.
On the other hand, while fiddling with it get some fork oil and change it. It's gotta give you a better ride!
Bare

[2bikebill]

I changed the fork oil just 100 miles ago. I did check it today and there's plenty of nice clean oil in both sides.
Perhaps it preferred that grey sludge that was in there before.....

[Ducati Scotty]

How much oil did you put in?  It should be 200ml for G5/B5 and 195ml for C5.

Scott

[Arizoni]

Have you checked out the center stand to make sure it is tight to the frame and doesn't have any overly loose fits on the rotating parts?

Sometimes sounds seem to come from places other than the one that's causing the problem.

The only other thing I can think of is some wear inside the fork tube.
When the bike is sitting on its wheels there is a torque inside the fork leg that loads up the bearings against one side.  When the bike is on the center stand with the front wheel lightly touching the ground there is almost no torque being applied to the fork leg.
This could allow the sliding tube to centralize itself in the worn bearings and any movement could allow the tube to "clunk" against the bearing when a small load was applied to the wheel.  (Does that make sense?)

I don't know what would cause this to happen now because if it were the case, it should have been building up progressively over the years.
That is to say, it shouldn't have come on suddenly.

[barenekd]

The shop manual sez 265ml. I think the G5 would hold more than 5ml more than the C5 as it has about an inch more stroke. I'd add maybe 40 more ml of oil in the forks. I have heard that 265 is too much, but it sounds like 200 isn't enough.
Bare

[2bikebill]

My owners manual says 200ml so that's what I put in. That's significantly more than was in there from new, so I doubt the exact amount is critical. Less than 2 inches showed on the dipstick previously - now there's 4 or 5 inches showing.
That does make sense Ari - the noise is definitely from the area at the top of the forks, and it occurs on the upward movement when I rock the bike, as the forks reach the completely uncompressed position. This only happens on the stand - I can't make it do it at all with it off the stand, even rocking the bike violently through the full travel of the forks. But it hasn't happened at all before today.

[Ducati Scotty]

The service manual and owner's manual don't agree for the G5.  I would say 200 is a minmum to cover the works but you could go a bit more if you want to make it stiffer.  40ml sounds safe to me. 

The C5 fork is shorter and tended to blow seals at 200ml so that's why we go with 195ml.  I don't think thats' documented andwhere but on the Indian forums.

I took a G5 apart recently and it only had 150ml in each leg.  It felt much better with 200.

Scott

[2bikebill]

I'll certainly try a bit more oil, but the 200ml I put in is a lot more than I drained out! There's something gone wrong in there methinks. I'll give it a run tomorrow and see what the local bike man thinks... 
Thanks all for the input chaps.

[chapel]

Hi there,
Did you just drain the oil out from the top or did you disassemble the forks completely? Also, what weight oil did you use?
Greg

[2bikebill]

The G5 has cap nuts at the bottom of the forks for draining the oil. I removed them and let it drain out - nasty grey sludge! I re-filled with 200ml of Silkolene SAE 10 fork oil.
Actually - I'd forgotten this - I did have a problem getting the LH cap nut off - it just turned in both directions. Something inside was turning with it. Eventually I used an impact wrench (well - a tight spanner and a whack with a club hammer - same principle) and that shifted it. Now I'm wondering if something was dislodged with all the previous turning back & forth of the stuck cap nut? The diagram in the workshop manual isn't all that helpful in seeing what's connected to what.

[Ducati Scotty]

It's connected to the damper rod and it's not uncommon for it to turn.  An impact wrench is the usual solution.  Don't worry, you didn't hurt a thing.

Scott

[2bikebill]

Thanks Scott, that's reassuring.
This afternoon I took the bike to our local bike mechanic - a long time rider of Enfield trail bikes. He said the forks were "topping" and it's nothing to worry about, since it doesn't happen on the road, only on the stand. I told him I'd changed the oil about 100 miles ago, and he thought perhaps I should try something heavier in there, although he agreed the damping is fine as it is. The SAE 10 I put in the forks is certainly a lot thinner than the (not very much) grey sludge which I drained out. Perhaps it took the 100 miles to work through the system. Anyway, I'll try something a bit thicker. Not sure whether to go for 15w or 20w. Is there that much difference?
 Thanks for your input Guys. I'm greatly relieved that it's nothing to worry about and I can carry on thumping....

edit - just remembered your definitive fork oil thread from last year Scott, which I had saved. Thanks again for that - I'll try 15w oil next I think...

[Ducati Scotty]

Since you say SAE 10w I'm guessing you're using motor oil.  You should get some fork oil at a moto shop.  It's made for doing just this job.

I have 10w fork oil and it was a little thicker than what I pulled out of there.  I notice fork oils tend to look a little thicker than motor oils of the same weight.  Try some 10w fork oil.  If that seems a little off go 15w.  There's a big difference between them.  Only costs a few dollars/quid to try a few.

Scott

[2bikebill]

No I am using Silkolene fork oil. I've ordered more of the same, but 15w. Strange that this clunking started soon after changing from what looked like thick grey sludge to something decent...