I picked up a 87 Ysr 50 a while back and inside of the tank is a little rusty. It's not terrible, but I don't want it to get worse or cause carb issues, etc in the future. What is the best thing to do? A buddy of mine that used to work at a shop told me about a product they would use to treat the inside and then put a coating on, but that was years ago and he doesn't remember much about it. What sayeth the beeb?
Put two cheapass fuel filters inline after the tank and change them out every so often until the rust goes away.
You can mix up a weak solution of muratic acid(pool cleaner) water and swish it around with a handful of some small hex nuts or any small metal parts to provide a scrubbing action to the internals. I did this on my old RD250 tank that was really bad. Turned out really clean. I didn't opt. for the sealer because it wasn't leaking. It still has not some three years later and clean as a whistle.
Thanks automan and noles! Why does it not surprise me that there was a better answer than Metalheads. (I am too lazy to type the new name)
I have an old Honda ATC125m that had a very rusty tank. I bought two bottles of 'The Works"toilet bowl cleaner at Home Depot and a poured them into the tank and let it sit for an hour. I then threw in some big nuts and bolts and kept shaking the tank with the solution still inside. After alternating letting it sit and coming back and shaking it for around 4 hours total time, it was clean!! I had heard that you need to re coat the tank but I never did, I just kept it filled to the top with fuel and rust never came back. It still looks new. It only cost a few bucks.
Best thing I we have seen or used is 'metal rescue'. The stuff is awesome and works just like in the youtube videos you're going to search... It's distributed by WPS so any local cycle shop can source it for you. Doesn't harm paint, no need to coat the inside, etc.
Use the stuff from Rusteco. I have a 92 YSR50 that the tank was so badly rusted I had trouble getting the cap to open. After I finally opened it the inside was a mess. I went the lazy route and sent them the entire tank to dip. It came back looking like it was brand new. That was in 06. Tank still looks brand new. Didn't do any damage to the original pain even. I was warned to stay away from those coating type ones. The coating is a mess and wears down over time and causes issues with contaminating your fuel. http://www.rusteco.com/
I sent mine to Team Calamari and they cleaned it and coated the inside. It's been perfect ever since, and that had to be at least ten years ago. I'm not sure what they used but if you call them they might tell you - they are super nice and they seem to know everything there is to know about YSR50s. www.teamcalamari.com
Muriatic acid. It's cheap and effective. I've used it twice with great results. It'll remove the rust in 1 minute. No need to use nuts, bolts, screws, etc to loosen the rust if it's light. You will have to neutralize it immediately once you remove the acid from the tank and then I would suggest coating the inside of the tank with some fogging oil. If you don't get it right the first time, there is no harm in trying again unlike the tank coating products. They're one and done. If you don't get it right the first time, you're screwed.
No, you can leave them installed to contain the acid while you are "swishing" it around. The acid won't harm the rubber. By the way, make sure you do all of this OUTSIDE and take the necessary precautions (i.e. eye protection, gloves, etc). The acid fumes are STRONG!
No love for the KREEM product line? I have used it a few times and had it work great, but the last time I used it less than 4 months later a big piece of the liner was "floating" in the gas and the tank again rusted under that lifted liner. It was a pain in the ass to fix but I ended up sand blasting the interior til it was all gone then re coated and it has been 3 years since and still working fine. One of my bikes had it in there for over 12 years before I sold the bike, without issue