Sealing My Fuel Tank With Red-Kote

So to start off, I picked up a second 1992 Kawasaki ZX-7 that I found on Auto-Trader. I was actually searching around for a newer bike when I came across it, but since I have been on the lookout for another one of these bikes for quite a few years, when the opportunity came knocking, I couldn’t say no. There’s just something about the front end of these bikes that really makes me smile.

Overall, the bike was in good shape for its age. The owner had done a bunch of mechanical work to it, cleaned out the carbs, changed the fluids and installed new tires and brakes so it would pass a safety. On top of that, he had given it a fresh factory quality paint job. The cost of the fairings alone, was worth the price of the bike. He had put a bunch of money into the bike with the intention of keeping it, but apparently his wife pulled the plug on the whole operation and told him to get rid of it. I could tell that he really didn’t want to sell it, but sometimes keeping the peace at home is worth the price.

Despite the fact that the bike was in good shape, when I looked inside the fuel tank, it was obvious that it was going to need a good clean out and maybe sealing. Not a huge job, and considering how rare these bikes are, I picked it up anyway. Cards on the table, I’ve never sealed a tank before, but I’m pretty mechanically inclined, so I figured it would just be another skill to add to the list. After doing a bit of internet research, this is the path I chose to take.

Step 1: Removing The Rust

To remove the rust in the tank I went with Apple Cider Vinegar and BBs. I found a lot of options online, but ACV provided the acidic content to loosen and remove the rust, while at the same time being environmentally friendly, so I could just flush it down the toilet when I was done. I chose to go with the BBs because I felt I could get a lot of them in the tank and they would get into all the small areas to knock off as much rust as possible. I picked up the ACV at my local grocery store for about $6 a jug and I got the BBs at Canadian Tire for $9 for 1500 of them.

To start with, I took one of the fuel outlet lines and ran it to the other outlet stem to essentially seal the tank on the bottom. Then I filled the tank with the ACV and let it sit for 24 hours. It took about 3 1/2 four liter jugs to fill the tank all the way to the the top. After 24 hours, you could already see that it had removed a bunch of the rust. There were chucks and bits floating around in the tank and the ACV had a slick rusty sheen on the surface.

Next, I drained out the Apple Cider Vinegar through a filter to get out the big chunks of rust. Then I put about four litres of the ACV back into the tank and added about half of the 1500 BBs. I shook the tank around for about 20 minutes to let the BBs knock off all the remaining rust. After that, I drained out the ACV, filtering it again and then proceeded to remove the BBs.

So, this part was a pain. Because I was doing a large sportbike tank and not a smaller dirtbike or teardrop style tank, getting the BBs out proved to be pretty difficult. The tank has a pretty odd shape on the bottom and so the BBs wouldn’t just simply roll out the outlet holes like I had imagined. On top of that, the top of the tank at the fuel opening, is turned back into the tank so the BBs wouldn’t just roll out of that end either.

I ended up spending about 3 hours refilling the tank with the ACV and then draining it out the outlet holes over and over again, each time getting 20-30 BBs out. As the number of BBs in the tank became smaller, the less came out with each try. Once I finally got it down to about 10 BBs, I just turned the tank over and kept shaking it up and down to get them out of the main fuel opening. If you’ve ever lost a pick in a guitar, it was kind of like that. Except way more frustrating. That last BB felt like it took forever. When I finally got them all out, I was pretty surprised at how much rust had come out of the tank.

The upside to using the BBs was that they did a great job at cleaning out all the rust. They’re small enough to get into even the smallest areas inside the tank and because there are so many of them it doesn’t take that long to knock off all the rust. The downside to using the BBs was getting them back out of the tank. Would I use them again? Definitely, just maybe not in this type of tank.

Step 2: Prepping The Tank

To prep the tank, I first washed it out with some degreaser and a little bit of water. I rinsed it a few times until it was clean and there were no bubbles forming in the pan when I drained out the water. I used a degreaser that I had in the garage, so I’m not sure where I got it or how much it cost.

Next, I used Muriatic Acid to etch out the tank and prepare the surface metal for the Red Kote. I picked up the Muriatic Acid at Canadian Tire for about $8. It’s pretty intense stuff, so make sure you wear gloves and goggles when you’re using it. Even a small drop splashing into your eye could send you on a quick trip to the hospital.

I sealed the outlet holes with old ear plugs and tape, put in a small amount of the acid, maybe 8-10 oz straight with no dilution, and shook around for about 15 minutes to prep the metal. When I dumped it out, it had a pretty dark orange colour to it, meaning there was still some rust in the tank even after the ACV and BBs. I then rinsed the tank with distilled water a few times and let it sit to dry overnight.

The next day, when I looked inside the tank there was quite a bit of flash rust that had developed overnight. I knew that there would be some flash rust, just not as much as there was. Even though the Red Kote states that it is designed to cover over small amounts of rust, I decided to use the Muriatic Acid again. I used the same 8-10 oz as before, but this time I diluted it at a 1:1 ratio with water and shook it around for about 10 minutes.

When I drained it out, there was quite a lot of small rust particles that came out. I repeatedly flushed the tank with water until it was draining out clear and free of any particles or colouration. It took about 3-4 times, using about 3 litres each time.

Next, I added the acetone which I got from Canadian Tire for about $9. The acetone is what Red Kote states to use before application. It absorbs all the water that is left in the tank from cleaning and rinsing, so the metal isn’t wet when you apply the Red Kote. I added half the can to the tank, shook it around and drained it. Then I repeated the process with the second half of the can. I tried to get it all out before putting in the Red Kote, but because of the shape of the tank, there was a little bit of it still in there. The instructions on the Red Kote state that you can cut it with up to 20% acetone to make the solution thinner, so I figured the little bit that was in there wouldn’t be a problem.

Step 3: Applying The Red Kote

Applying the Red Kote was pretty simple. I plugged the outlet holes on the bottom of the tank using old ear plugs and tape. Then I taped newspaper around the fuel opening on top to protect the paint. The warnings on the Red Kote state that you should apply it before painting, because the Red Kote can really eat away at your paint job. Unfortunately, this wasn’t an option for me, so I had to tape around the top of the tank and be careful not to spill any of the Red Kote on my paint.

Next, I put in about half of the pint of Red Kote using a funnel. Then I placed a piece of plastic over the fuel cap before locking it shut to keep the Red Kote off of it. From there it’s just a matter of turning the tank around slowly in a continuous motion to let the Red Kote cover the entire surface area inside the tank. You don’t want to shake it around or you can make bubbles which might affect the coating. Just keep turning it, bit by bit, letting it sit for 1-2 minutes in each position.

I did this twice around the entire tank to make sure that I had coated everything. It probably took about 30-45 minutes in total. Not very long, just a bit boring. Once I was happy that I had covered the entire tank it was time to drain it out.

To drain, I just took off the tape and pulled out the plugs, and then let the excess Red Kote drain into a plastic pan. Quite a bit of unused Red Kote came out. I tried to keep moving all of the excess down towards the outlet holes to get it out. The instructions state that leaving pools in the tank can cause it not to cure properly, so I just kept trying to drain everything until nothing was coming back out the outlet holes.

From there, I let it dry for 4 days before putting gas in it. The instructions say that it cures in 8-24 hours, but I had read online that you should leave it for at least 2 days minimum just to be safe. I gave it an extra couple days because it was pretty rainy and humid, so I wanted to make sure that the lining was fully cured.

Step 4: Filler Up And Test It!

After the 4 days, I hooked everything back up, put the tank back on the bike and put some fresh premium gas in it. I let it sit with the new gas in it for a day before actually starting the bike, just to make sure that the lining wasn’t going to peel off. It’s now been a week and everything is still looking good.

So that pretty much sums it up. Hopefully this gave you a little direction and maybe a few ideas about sealing your own tank. It’s not really a hard job, you just need to take your time and don’t rush it. The most important part is prepping and cleaning the inside of the tank. If the surface metal has any oils or water on it, the Red-Kote won’t stick.

Thank you to Canadian Heat Transfer Solutions (1-877-705-6521) in Owen Sound for getting the Red Kote to me so fast. They are the only dealer in Ontario that stocks Red Kote and their shipping times are incredible. Same price as anywhere else online ($65 delivered), but you’ll have it in your hands a lot sooner. You can follow me on social media for more content, just click the links below! If you found this article helpful please take the time to share it on social media!

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I'm a motorcycle enthusiast, photographer and graphic artist. Lover of anything with two wheels and an engine, especially sportbikes. Gearhead with a sometimes frustrating obsession with carburated technology. Photographer who strives to capture the moment in a single picture. Graphic junkie with a desire to colour up the world of sportbike design and apparel.