Filler style


Premier Member
IBA Member
I'll never ever fit a key locking flush mount filler cap again. Top quality unit that it was it robbed usable fuel space out of any and all tanks if its not mounted in some sort of short neck Say 50mm long. . And it leaked up through the lock barrel. ( if you want to strap a swag on top of the tank then you.ll understand some load problems) hence short necks for the caps. Lockable flush caps are much larger diameter and need to be considered in a tank design. Like how it fits with the bike on the side stand and what fuel volume your not going to get . And then the screws. Tapped holes or nuts and washers. gaskets both sides? etc
Just think of how much space the stock cap on a main tank takes up. Needing a key to access the things sucks too.

I've dropped my ST at speed onto the right side on a very uneven surface and didn't rip the filler neck off. Dropped it another time into a low brick fence and the tank neck took all the weight of the bike. No dramas.
Maybe because my tanks are rubber cushion block mounted at 4 or 6 points depending on the bike.
I bend my filler necks as one part not cut and welded. And I keep the design so the neck is well within the side profile. All that helps.
Oh and a filler neck gives you some notice of almost full with a bit of wriggle room before the fuel is splashing out of the tank.

Ive used Jaz tanks in the past but these days Li like a tank designed for that particular bike. But I'll never use a flush mount cap ever again.
This is not going to break loose:

The tank is really nice - good workmanship, but YES, it will break! The welds will hold because the metal is thicker. The sheet aluminum will tear. Think about it. A 600lb bike falling against an 8" inch tube, acting as a lever, will rip the tank or split the tube. If the bike is moving at any speed, the force and torque applied will be in tons instead of pounds. I think the calculation is something like the force of impact increases with the square of the increase in speed. A lot depends on whether the filler tube is hit square or with a glancing blow.
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In the kind of impact you describe, all bets are off.

My point was that the filler neck isn't a particular vulnerability ... The 1/8th" aluminum is tougher, and less likely to break than the skinny steel of the OEM tank.