Fork top bolt question...........

[TimClarke]

P3050012.JPG (97.17 KiB) Viewed 2112 times

I attempted a fork oil change today but backed off as when I went to undo the fork top bolts (the ones you remove to pour the oil into the forks) they werent allen bolts as i initially thought but some sort of odd "star" style bolt. I'll have to buy a socket for them and before I do I'd like to know exactly what it's called so i buy the right one please??

[Morini Jen]

Hi Tim.

Sounds to me that they need a Torx bit or screwdriver. They are widely available.. Screwfix, Halfords, Machine Mart etc..

[morini_tom]

If you mean the small screw in the top of the fork top nut, i’ve always found it slow and messy to get oil in via that hole. I tend to just undo the whole top nut (one side at a time) and pour the oil in. With the bike on the centre stand it’s fine to do one at a time without the need to jack the front up too.

Also allows a check of the springs and fork internals, and setting of oil level by distance from the top (air gap) rather than just relying on volume going in.

[Steve Brown]

This is always the challenge with bikes this old. Unless they've been unusually well cared for they can throw up all sorts of head scratchers when you find one of the 47 previous owners has been 'creative' with maintenance and repairs. Or is just an unqualified bodger. Qualified bodgers like me are worth believing in.

[Morini Jen]

Actually, looking at the photos of Tims bike in the auction, the fork top nuts aren't the same as the ones that have a small countersunk screw in the top.

(The photo of the K1 Sport top yoke is of Tom's bike when it was up for sale)

[Steve Brown]

The top pic is of the type as in the older forks. The hex socket in the top had a countersunk screw that was a slotted type originally. I suspect his were replaced at some point with 'something close', like BA fitters used to do with windscreens replacements till they had that nasty incident at umpteen thousand feet. The original screws spring loaded a ball bearing on a seat, as a check valve.

[Morini Jen]

Well, I never knew that. I'm not familiar with the older style ones. Thanks for that, Steve.

[TimClarke]

Actually, looking at the photos of Tims bike in the auction, the fork top nuts aren't the same as the ones that have a small countersunk screw in the top.

(The photo of the K1 Sport top yoke is of Tom's bike when it was up for sale)

Ah that was silly of me - I should have taken a photo. I'll take one in the morning - when you look at the top of the fork there is a sunken bolt that initially looks like an allen bolt but it's actually a wavy/torx style bolt and there is a countersunk screw at the base of it as well. It doesn't look like a replacement if you know what i mean it looks like it's been in there forever. It looks like it's ally as well not steel hence my keenness to get a really well fitting socket to get it out!

[TimClarke]

If you mean the small screw in the top of the fork top nut, i’ve always found it slow and messy to get oil in via that hole. I tend to just undo the whole top nut (one side at a time) and pour the oil in. With the bike on the centre stand it’s fine to do one at a time without the need to jack the front up too.

Also allows a check of the springs and fork internals, and setting of oil level by distance from the top (air gap) rather than just relying on volume going in.

Yes, that makes sense and that's what i will try and do cheers

[TimClarke]

Hi Tim.

Sounds to me that they need a Torx bit or screwdriver. They are widely available.. Screwfix, Halfords, Machine Mart etc..

Cheers, yes they look like torx but maybe a bit "wavier" but that ma be because they have been roughed up a bit in the past!

[TimClarke]

Hi Tim.

Sounds to me that they need a Torx bit or screwdriver. They are widely available.. Screwfix, Halfords, Machine Mart etc..

Cheers, yes they look like torx but maybe a bit "wavier" but that ma be because they have been roughed up a bit in the past!

Here's a picture!

P3050012.JPG (97.17 KiB) Viewed 2114 times

[AntietamClassicCycle]

Looks like a standard M12 hex bit to me. <shrug> It sometimes helps to loosen the top pinch bolts before attempting to remove the top plug.

[George 350]

The top caps in the picture would originally had a (slightly tapered!) hex which took a 12mm hex key. The taper on the hex is so the cap would come out of the casting die.
As for the small M6 c'sk screw in the centre, as has been mentioned, there should be a small spring and ball bearing under it so acts as a 1 way valve.

[Steve Brown]

They just look like worn hex to me, rattle gunned maybe? Or imperial/worn keys used?
Mdina may have new or used items available as these forks were used on other Italians Ducati especially. If new are available I'd get some and use informed bodging techniques to get the old ones out. As Charlie says too, slacken the top yoke pinch bolts first.

[George 350]

And if you go for replacements, make sure you specify the thread pitch you need! Both 1mm and 1.5mm pitches were used.
If Mdina have no stock, classic ducati might well have.
See: https://www.classicducati.com/products ... ork-plugs