FOAK: Best way to clean the inside of a steel motorcyle tank?

You folks are and endless supply of kindness and good will and now I
return to ask your advice:

Old tank, the debris from it is plugging up the carbs.

Some methods: fill tank with diluted muriatic acid, drain and flush.

Fill tank with diluted naval jelly, drain and flush.

Fill tank with acetone, drain and flush.

Fill tank with 50/50 chlorine bleach and water, drain and flush.

Any others?

Thanks in advance,

Biker Dude

 

1) Evapo-rust (available in Canada, don't know where else) is rather
'green', stronger than other mild acids but still save to pour down the
drain, although it is re-usable. Have used it twice on 20-year old
tanks that had mild rust including loose rust - it took about three
hours each, just plugged up the holes, put two litres in (cost $20),
propped tank at various angles for 20 minutes each, after each rotation
gave it a shake with a two handsful of small smooth river stones (from
the dollar store). About to try on some thick rust, looks about 1/8"
inch thick. After emptying the evapo-rust, used a few capsful of methyl
hydrate to dry, re-attached petcock (evapo-rust can hurt rubber seals)
and filled immediately with fresh gasoline. If that doesn't work am
going to try 2).

2) Electrolysis, small dumb battery charger, chunk of old iron, washing
sode, water, plastic tub. Only disadvantage I can see is that one may
have to re-paint an external tank afterwards. The left-overs are also
flushable.

 

Two litre bottle of non diet Coke and a handful of M8 nuts. Good old shake
around and leave the juice in there for a few hours, moving it around.
Works every time.

Just flush it all out properly with water afterwards and let it dry in the
airing cupboard of an evening.

 

First drain it and dry it out. Remove the drain tap assembly.
Then insert a beermug full of fine gravel, fit the fuel cap and shake
until your arms hurt. Take a rest and repeat twice.
Empty out the gravel and shite, rince with petrol, dry out then treat
with tank sealant.

 

Buy a Kreem gas tank sealing kit.

It contains phosphoric(?) acid for removing the rust and a liquid
epoxy for sealing the etched surface so it won't rust as quickly as if
you'd just left it bare.

If you google back in rec.motorcycles.tech you will also see
references to a similar product called POR-something or other.

 

A nice dollop of ordinary petrol, several handfuls of nts and bolts or
nice clean gravel, replace tank cap, attach tank safely to a small
cement mixer, and let it churn and rotate for half an hour or so.

Remove nuts and bolts or gravel, flush with clean fuel, inspect and if
necessary repeat.

 

I've had pretty good luck with a POR-15 tank treatment.

Three step POR-15 process:

1) Soak and rinse with lye to get out the hydrocarbon glop.

2) Fill with phosphoric acid solution and something like sheet
metal screws to knock off rust and loose liner. Soak, shake,
repeat as ambition dictates then drain and rinse.

3) POR-15 liner. Slosh around in tank, let sit for a while, then
drain.

The kit comes with better directions. This is from memory.
Watch out not to expose paint that you care about to the
various chemicals. Definitely remove the petcock(s) before
starting. Watch out for POR-15 and aluminum. (seems to
attack it).

POR-15 is supposed to work better than Kreme. There are
other treatments around too. I suspect the preparation part
would be the same for all.

 

In message

If you don't fancy DIY there's a chap that advertises in the VJMC
Autojumble mag that can apparently return the inside of the tank to
shiny bright metal again, I'll dig out his number if anybody wants it.

 

Many people will suggest a mechanical method of getting the crud out and, in
the past I would also have suggested "a handful of mixed nuts and a good
shake".

However, while this was fine for bikes of the mid-80's and earlier, which
tended to be made of thick-gauge steel and have a simple hole for the
filler, later bike tanks are usually made of much thinner steel and have a
neck in the filler.

This means that anything (nuts, stones, etc) you put in the tank can result
in embossing the surface (dents from the inside) and will be a bastard to
get them all out. I know two people who fell into this trap. The first
tried to sand down the small bumps and ended-up with a tank that was covered
in holes like it had been hit with a shotgun. The other ended-up with a big
dent in the side, as it hit the wall while he was trying to get the last
stones out. This had to be filled and each of the raised bumps had to be
knocked-back with a pein and filled, before the whole thing could be
repainted. The result was a mess and he bought a s/h tank and started
again, this time using 8mm nuts, with the idea he could fetch them out with
a magnet-ona-string; forgetting that the tank was made of steel...

 

And morphing again.

 

Well duh...very easy to spot, just look for the absolute lack of any
real knowledge.

 

Projecting *again*?

 

Nope oh ignorant nazi pedarast.

 

1/4 fill it with sand & shingle, strap it to the back of a flatbed truck and
spend the day offroading in it.

 

I thought that would be a requisite before you even start working on the
tank

 

With the electrolysis you don't have that issue. Though you will wear
out a prob or two. 8^)

 

Drywall screws seem like a good idea until they wedge themselves in
the corners of the tank. Then they are a right pain to remove.

For chemicals, I like the phosphoric acid because it changes the
remaining rust into a protective hard grayish-black layer.