Round 6, FOAK: 1982 Kawie KZ550 C3 LTD Restoration Options Options

I did manage to change the tire and the bike is up and running! This
ole hoss breaks down all the time due to age and if something is
running right then a little speed and vibration is all it takes to
make something start leaking oil or gas or air out of the tires.

I now have my choice, should I change the chain and sprockets or fix
the fuel leak and upgrade the whole fuel system?

Will repair the fuel system next. The bike leaks gas when it sits.
New repair kit for the vaccum tap, new carb kits and carb cleaning.
New fuel and vacuum lines to the tap.

I do know that the tank has some rust in it, should I apply one of
those inside-the-tank coatings? Should I add an extra fuel line
filter to catch all of the rust before it arrives in my newly-cleaned
carbs?

Four sets of carb gaskets cost about a hundred bucks. Tap kit is
about twenty. How much does the tank sealing material cost?

<duck for cover>

Thanks in advance,

Biker Dude

 

Look up electrolysis. It works and I'm sure that krusty the uninformed
plagerist will say other wise. THEN look into a tank liner kit...I
wont recommend any as I've not HAD to use one. I just braze up the
leak adn quit worrying about it...but I have skillz wit a torch.

 

Yes, absolutely.

Google for it. Look for something called Kreem, There's something else
called POR-something or toher. And here in the UK we have Petseal, which
has just been used to treat a tank of a bike I'm restoring. From memory,
about £25-30, so 45-50 bucks?

 

I'm going to add a note of caution about the tank liners, they don't
last forever - we had herself's GN250 tank lined with Flowliner a decade
or so ago. I exhumed the GN last week for winter commuting duties and,
when I opened the filler, the lining was flaking off. No idea if the
tank was usable or if the lining could have been removed as I just
replaced it with a spare tank.

In fairness to the lining, it did last more than 10 years and, having
removed the tank from the bike, I reckon the tank would have been
unusable years ago as the underside of it was unbelievably rusty. When
the current tank starts to look rusty inside I'll get it lined as well
and that should see out the rest of the bike.

 

I suppose 10 years is pretty good going. One thing I have noticed is
that the coating is heavy - my TS250ER tank has added about 30% in
avoirdupois, I reckon.

 

Oh yeah - I was annoyed when I saw the flaking then had to think about
when the lining had been applied... can't grumble at more than 10 years,
especially when I saw how rusty the outside of the tank had got.

The lesson I'll draw from that is that although the inside doesn't rust
once it's lined you can't guarantee the underside isn't rusting. I'll
just need to remember to pull this tank off come summer & de-rust the
underside. Or swap it for the NOS GN tank on the shelf.

Come to think of it, I've unscrewed the tank badges but they are still
stuck fast to the tank. I suspect there isn't much structural integrity
under the badges.

Not bad for 14 years as year round commuting wheels followed by a
further 5 years as winter hack. Not sure I'm looking forward to pointing
out to herself that she's owned that bike more than half her life.

I was going to get the Laverda tank lined as they are notorious for
rusting out the front corners but the tank is so vast it would need a
couple of kits and I dread to think what that would weigh.

 

Notorious weak spot on a lot of tanks, that. Water trickles down
behind the badges and gets trapped. The Kawa GT550/750 fours suffered
from it. I used to take the badges off mine every year ot two, and
dollop a load of grease beind them. Never had a problem.

 

Bad form and all that, but something occurred to me just now - I think
this was the first time we had put the bike away with an empty tank.
Wonder if sitting with a tank full of petrol might have prevented the
peeling?

 

No idea. Ask a materials specialist?

 

Maybe. You have to consider the effects of long term exposure to
alcohol upon epoxy.

You can build an airframe from fiberglass or carbon fiber, but if you
want to
carry gasoline inside an integral composite tank in the wing or
fuselage, you have to use epoxy to bond the fibers together, because
alcohol will gradually eat up the traditional polyester resin that's
been used since the 1930's.

Volatile alcohol additives are the first fraction to self-distill out
of stored gasoline.

But, if the tank is empty, rust will start finding its way through the
epoxy tank liner.

Did you know that the pressure vessel of the Apollo command module was
all
epoxied together to make a very strong, lightweight structure?

We had to go to extreme degreasing of the surfaces and then abrading
them with Scotch Brite abrasive pads to get the epoxies to stick to
the parts that we were bonding together.

We had to prepare a test specimen with every joint we bonded together
and it was pulled apart on a tensile strength tested to prove its
strength.

Of course you cannot get inside of a motorcycle gas tank to abrade it
evenly, unless you want to sandblast it inside.

So the Kreem kit gives you some acid to etch the inside of the tank,
and how long you allow the acid to work and how you neutralize the
acid and dry the tank out will determine how much oxidization starts
on the inner surfaces before you get around to pouring the liquid
epoxy into the tank...