tech12

When I purchased my 1966 BSA A65 Hornet about six years ago it was in
a sorry state, appearance wise. The good news was that the oil that
encased it acted as a preservative and simply removing the oil
revealed a good bike underneath. The frame paint was fine and only
needed a simple polishing out using mild polishing compound. But the
fiberglass tank needed major work. The surface gel coat was a sea of
micro cracks. It appears that the bike had been involved in some sort
of accident where the primary side foot peg kissed the primary cover,
making a small crack that leaked oil. The welder fixed that. The
tank’s micro cracks were mostly on that same side, I assume from the
riders knees hitting it hard. So I took it to a fiberglass repair man
who laid a very thin layer of cloth on the surface and re-gel coated
the entire tank and two side covers. It looked better than new! After
riding it for a handful of BSA club rides the tank started to leak.
The tank was made up of a top piece glued in a vertical seam to a
bottom piece and the seam between the two pieces was leaking. The
“glue” had become soft in several places and allowed the gas leaks. I
dug out all the soft glue and reglued the seam at various points with
two part epoxy glue from the hardware store. I was careful to use the
longer curing, higher strength variety. All was fine for a year or so,
then different parts of the seam started opening up. Again I dug out
the newly softened glue and epoxied the seam again. Each time it was
at a new spot on the seam. On one repair I used the wrong epoxy (the
more pliable type for plastics) and it didn’t even last a week. It
seemed that I had to fix a leak every time I rode it.

In the mean time I built a new Rickman Triumph motocrosser with, you
guessed it, a fiberglass gas tank. The new tank was well made, by
Avon, the original Rickman fiberglass manufacturer from the 1960’s.
After using it for about a year or so it started to delaminate from
the inside. Now lets see-two fiberglass tanks and two leaking tanks.
Whats’ common?-the gas! It seems that the “new” gas loves fiberglass
as a source of food! I had the Rickman tank repaired but It seems to
be delaminating again despite never storing gas in it except to ride,
and internally coating it with the “correct” epoxy resin.

For the BSA I coated it internally with an epoxy resin based coating
especially developed for gas tank coating (Caswell). In fact, they
verified via e-mail that it was exactly for fiberglass tanks while
other coatings manufacturers nixed the use of their products on
fiberglass. Guess what- it still leaked.

I did a little informal survey, verbally and via the Internet, as to
other’s problems with their fiberglass tanks. Those who have in recent
times used straight race gas (no MTBE or alcohol) do not seem to have
this problem. Speed and Sport, who has imported and restored Rickmans
for over 14 years has never had a problem with the bikes that used
race gas. Others that have used race gas in the past and changed back
to pump gas have had the same problem as me after returning to pump
gas. The problem is the gas! And it will probably get worse when they
remove MTBE and replace it with alcohol or another nonnative to gas
product. The solution is not store or put gas into your existing
fiberglass gas tank. How do you ride it then? I haven’t a clue if you
want to retain the fiberglass tank.

My solution was to buy a new aluminum BSA Goldstar 2 gal competition
tank for the BSA that has the same basic lines of the original Hornet
tank. It is not a perfect copy, mind you, but makes the bike look like
a competition BSA A65 from the 1960’s. Speed and Sport is importing
them from England and the build quality seems good. The price is up
there but not really prohibitive. I paid nearly as much for the re-gel
coating of the original tank and side covers as I did for the new
aluminum tank. The cost is only a little more than a repaint of an old
steel tank. For the Rickman I am searching out an optional aluminum
replica tank made by the current Rickman company in England. It is
hard to fault aluminum as a gas tank. You must mount it well and
assure it doesn’t touch anything other than the rubber mounting
points. It requires polishing to look good. And you must never clean
the surface with anything other than mild soap and water (A friend
found out about how to etch aluminum with the wrong cleaning agent).
But it doesn’t rust, or get eaten by gasoline, or require expensive
paint jobs that get easily marred and it is very light. It does dent
but there are people who de-dent them usually without cutting them
open. With a little care aluminum gas tanks make a lot of sense,
especially for a race bike.