TOPIC:

curious how much kreem or por 15 does it take to line tank? ty

A 20 liter tank = 236 ml (1/2 of a pint) POR-15 Fuel Tank Sealer.

www.por15.de/Complete-Kits/Cycle-Tank-repair-Kit-20-l::12.html

The kit is the way to go.  It comes with a gas varnish remover, and a derusting solution.  And don't be fooled into thinking that you can seal over rust, because that's a fool's errand.  Derust to the greatest extent possible before sealing.

While ago, I sealed my tank with POR-15. I have late model KZ tank with 21.7 L capacity. My tank was somewhat in bad shape, so that may be the contributing factor.

I first had to work all the rust off using Evapo-Rust. I used around 3 Gal of that stuff. And because of my working schedule, I had my tank soaked on all side, which was laying my tank on right, left, top, bottom, front and rear side, for at least for a day. After I was satisfied with the result, I then followed the instruction that came with the kit. I believe the kit came with a pint of the actual coating material. When I was done, only little came out from my tank. I poured the entire can into my tank.

With that being said, if you have smaller tank, should be more than enough. I believe my tank is one of the bigger tank Kawasaki came out with, so even at that, you should have enough material to cover the entire tank.

Don't rush. read the instruction. Take your time. BTW, after you coat the tank, make sure you have somewhere you can store the tank. It smelled like diesel fuel and it will stay that way for next two weeks or so(I live in Hawaii but the weather didn't help. Hot or cold, smell will be there for some time), even after the coating has dried.

Somebody should come up with a custom rubber bladder that fits inside the tanks. You’d have to do away with the sending unit and overflow pipe and it would have to come up over the filler tube. And somehow mate with the petcock.
Hmmm, a thousand bucks should cover it.

I've used Por-15 on a few different tanks previously, and I think the key to getting a good seal is 1) derust really well, and 2) get several good thick layers of coating down on the inside.

Regarding 2), what I do is dump in the full can and then start flowing the sauce over the tank interior.  The hardest area to coat is the hump that sits over the frame backbone.  Watch inside the tank as the sealer flows, and concentrate on getting good coverage all over the inside.  Twist, turn, and flow the paint all over the inside, building layer upon layer until you have at least a couple of good 100% layers down.  Then, dump out the excess paint through the petcock opening.  Something in the range of half the can will come out.  After this, there will still be a good bit of sealer still inside the tank, so keep turning and flowing it inside the tank until it fully kicks off and stops flowing.  You should be able to get at least one additional complete coat inside the tank before this happens.  

Por-15 cures from soaking up moisture in the air, so it will take a few days to fully harden.  Don't be in a hurry, let the sauce harden at it's own good time before dumping gas in the tank.  And needless to say, don't seal over your petcock or fuel sending unit.  Make some plugs for heavens sake.  This should go without saying, but it's surprising how many people don't take the time.