The screws holding the filler cap...

[audiomick]

I'm in the process of fitting a ring on the filler cap to hold a tank bag. In the process, I've become aware that the original screws are apparently alternately long and short, i.e. 3 of them are M5 x 16 and 3 are M5 x 25.

Does anyone know why?

There is probably a perfectly sensible reason, but it just seems a bit weird at first glance...

[PJPR01]

If I recall correctly, the plastic receptacle into which the threaded inserts are embedded has that sort of "ridged" structure, hence the alternating length of the screws...I think looking at the bottom of the plastic would reveal more clearly...

I only noticed that same issue when I took the filler cap and screws to "blacken it" to make it look more "Scura like"...I do love the darkness and every silver screw exposed just needed to be blackened!  

[Scud]

3 screws hold it on, and three are essentially decorative. I assume the 6-hole pattern is an industry standard and Moto Guzzi only needed 4 screws to attach to the tank. I say 4, not 3, because there is a fastener under the lid.

...and as for blackening bits on a Scura... that is important work. 

[audiomick]

20 minutes ago, Scud said:

...three are essentially decorative...

Well, I hope the manufacturer of the tank bag knew that. Four screws holding the ring, and two of them in the short holes. It's one of these....

https://www.hepco-becker.de/tankring-lock-it-inkl-tankrucksackgegenhalter-fuer-moto-guzzi-scura-le-mans-ballabio-coppa-italia-cafe-sport-sport-naked-sport.html

 

Incidentally, the kit includes spacers that put the ring high enough to clear the chin pad. That means, on mine, no chin pad, there is nearly a half an inch breezeway between the bracket and the top of the tank. When I get the lengths of the spacers and screws worked out so that it sits down close to a tank without a chin pad, I'll post it here.

 

PS: I have absolutely no doubt that blackening bits on a Scura is the single most important thing in the entire universe.

[Lucky Phil]

1 hour ago, PJPR01 said:

If I recall correctly, the plastic receptacle into which the threaded inserts are embedded has that sort of "ridged" structure, hence the alternating length of the screws...I think looking at the bottom of the plastic would reveal more clearly...

I only noticed that same issue when I took the filler cap and screws to "blacken it" to make it look more "Scura like"...I do love the darkness and every silver screw exposed just needed to be blackened!  

One of the issues with fastener surface finish be it for colour or corrosion protection is it doesn't last and ages. Part of the reason all my bikes get the titanium fastener treatment. Titanium is not only light and strong but the surface finish remains in brand new out of the packaging condition for ever. Some owner in a hundred years is going to appreciate that.

 

Phil