Restoring a 1972 fibreglass Bultaco fuel tank

[David Lahey]

This Bultaco model 80 Sherpa T tank looks like it has seen a bit of action in its time.
I'm planning to use it on a Sammy Miller frame Bultaco I'm building.
What you see here is after about three hours of removing the layers of paint, to expose damage and repair work.
I used Acetone and many scourer pads to get the layers of one-pack paint off. I didn't want to damage the gel coat of the fibreglass, so I didn't use sandpaper to remove the paint.
Removing the one-pack paint revealed a few old crash repairs and areas of a stress-cracked coating that could be gel coat or two-pack paint.
My next step is to work out if there is two-pack paint on there or not.

[Gary Mc]

Hi David, just a query on the success of your fibreglass Bultaco tank repair, did it need the fiberglass repair or just the top coat of paint. I have a Bultaco Tiron fibreglass tank that needs a similar repair
Cheers Gary

[David Lahey]

Hi David, just a query on the success of your fibreglass Bultaco tank repair, did it need the fiberglass repair or just the top coat of paint. I have a Bultaco Tiron fibreglass tank that needs a similar repair
Cheers Gary

Hi Gary I didn't show it but the rear section under the seat had been repaired very poorly in the past and I've had to grind all those repairs away to do them properly so it will fit the frame and the seat. I'm waiting on a custom-made seat to arrive so I can do the repairs in a way that the custom seat and an In Motion seat fit properly.
The fuel-holding section had existing external polyester bog repairs that are visible in the photos. Most of them have been done well. I'm going to do a few more bog repairs in areas that had been damaged since the previous restoration.
By trying different types of paint stripper, I worked out that the red surface is gelcoat. I still haven't finally decided on how to deal with the fine cracking in the gelcoat but I'm thinking that when I line the fuel section with epoxy resin, the tank walls will become a lot stiffer than they are now. I'm leaning towards veeing out the cracks to the depth of the gelcoat and filling the vees. I'm not keen on trying to spray gelcoat

[Bully fanatic]

David try some 2 pack primerfiller to fill the cracks in the gel coat after you have sanded them as well as you can. Use it over the bog repairs too. It will handle any paint over the top of the primer. Use a guide coat over the top so you can see where needs to be sanded more. Black always works well.