Tank filler hole

[Tim213]

Hey guys, I’m getting ready to cut the hole on the skin for the filler tube and don’t want to mess it up. Since the top skin is already riveted I’m looking for advice. Ive read that others have cut the hole then when tensioning the tank down it moves and the holes no longer is centered. I have used lipstick on the tank rim and have marked the correct center for now but don’t know if I should cut the hole there or not. Any ideas that worked are greatly appreciated.
Thanks

[Battson]

Hard question.
I managed to get my holes within about 1mm, or 1/24 inch, however the one which was slightly off centre still smoked almost immediately.
Things always move around a little. Even the most perfect hole will let some water into the wing, when you park in the rain.
I used a neoprene layer under the wing skin to seal up nice and tight around the filler neck.
One option is using a doubler plate over the top of the wing skin, which you can match drill after the tanks are installed to their final position.

[rv8bldr]

Hey Tim

I posted how I did it last spring here (https://bearhawkforums.com/forum/bea...9842#post29842) . It eventually made its way to one of the editions of Beartracks. I'm going to do the same thing as Jono and use neoprene under the wing skin to keep out water.

Cheers

[Tim213]

Thanks guys for your suggestions, Battson I do plan to follow your advice and place a seal around the filler to seal up the tank area. Mark I followed your method and it worked well. I cut both filler holes today and the fit afterwards was superb. I made the first three tank straps and put them in and all seems good so far. So again thanks for helping curb my concerns about an incorrectly cut hole. More progress made today so thanks!

[rv8bldr]

Excellent! Always glad to help.

[PaulSA]

Here's a thought. Make the hole slightly larger than necessary so the exact fit isn't critical. Then make an exact size ring about 3/4" wide and with (say) 1/8" clearance. Cut a piece of neoprene or old inner tube to make a seal and sandwich it between the ring and the skin. Attach with rivets or (better) screws and nutplates