1982 Gs850 Rust in Tank

[Guest]

Just purchased a GS 850G that runs ok but has rust in the tank and otherwise in great condition. Trying to remove the rust using white vinegar and have purchased a new Petcock because am sure the vinegar has destroyed it. I am hoping the fuel sending unit is not also destroyed by the vinegar and looking for thoughts if I should replace this also due to the vinegar exposure. Not really that concerned if the fuel gauge works but more concerned about leaks or other problems. Thanks in advance.

[tom203]

New petcock is a good idea no matter what tank looks like inside: when you are done sloshing vinegar, remove sending unit and attempt to save it with rinse and oil spray. You'll need gaskets for both items.
It's nice to get nice looking bike, but figure it's way behind with maintenance. Have you see this ?

http://members.dslextreme.com/users/bikecliff/images/GSR_Greeting.html

oh yeah, welcome!

[Nessism]

It was a mistake to derust before fashioning some proper plugs for all the various openings. The sending unit WAS zinc plated but all the plating is gone now since the acid eats it.

[robertj1979]

Good information and thanks for replies. After trying to remove the rust, it appears it comes back very quickly as soon as vinegar is taken out. I decided to take the tank to a motorcycle mechanic I have known for years and trust. He told me he would put a coating in the tank that costs about $35 and hopefully eliminate future problems. One other issue I have noticed is that the "cage" for the air filter is missing. There is a K and N in there now but was not properly attached and is basically lying in the bottom of the air box. I could not seem to find a cage anywhere so will have to get creative I suppose. Really did not want to add pods as it is a totally stock bike and appears be in pretty good shape. The only other thing I noticed when removing the spark plugs is that three appeared completely normal but the fourth seemed somewhat fouled with oil? Hoping that is nothing serious.. Thanks for the link..

[Nessism]

You may want to post in the Wanted To Buy form for an airfilter frame.

Regarding the tank, be sure the guy isn't using Kreem. There are various sealer products on the market and Kreem has the worst reputation.

[tom203]

"After trying to remove the rust, it appears it comes back very quickly"

oh yeah... If tank looks good after sloshing,Try flushing vinegar and then get some 25/1 gas oil mixture to slosh around to coat insides. I'd only use a coating as a last resort.

[Phred]

I might have a filter frame from a few boxes of parts that I bought a few years ago. PM me and I will look for it.

[leftlostcommonsense]

As for the tank liner either use en epoxy based one which is somewhat expensive or redkote (35$) enough for 2 tanks. I've had redkote gas tank liners in all sorts of machines and never had an issue. I had gas pouring from the seams of my tank before doing the redkote and haven't had another leak since. Be sure to give ample time for it to dry and drain out the excess back into the can to be reused. The redkote likes a little flash rust to stick too also so it's no big deal, makes sure you get the tank dry though before pouring it in. I did a coat, poured out the excess, let dry for a week or so then did a second coat and then left it to cure for close to a month. IT MUST DRY BEFORE USING THOUGH! A simple day or 2 will not work... Simple job anyone can do.

To this day the liner is still soft as rubber even after texas heat and gasoline. You absolutely must pull the petcock and sending unit though and be careful of the paint.
Stay away from kreem and por15 too many videos of those failing, couldn't find any redkote fails that weren't caused by ignorance and impatience.

[Nessism]

My experience with Por-15 has been good. I disagree with suggestions they make that application over rusty metal is acceptable though. I always derust to the fullest extent possible before moving to sealing. Typically sealing is not needed if properly derusted though. Exception to this rule is if the rust is deep and has eaten through a significant portion of the metal. Sealing in those instances is best. To derust I use phosphoric acid. The same stuff that comes in the tank cleaning/sealing kits that are sold. Kleenstrip Etch and Prep from Home Depot is the stuff. You need to keep the metal surface coated by rotating the tank and sloshing the stuff around. It can be diluted too, it works just fine only slower. The left over can be saved for reuse and then rinse the tank out with clean water followed quickly with some alcohol to help drying and some WD-40 or similar oil to reduce/eliminate flash rust. Skip the last step if you are going to seal of course. No oil allowed.

[robertj1979]

Thanks for suggestions and information. I have taken the tank to a professional motorcycle mechanic I have known for many years and trust who specializes in Vintage bikes. I decided since I have not done this before just to let him complete it. After looking at the tank, he said he would attempt to get the rust out using acid and then make a determination if lining is the best solution. I will post once I get the tank back how it is going.

[leftlostcommonsense]

My experience with Por-15 has been good. I disagree with suggestions they make that application over rusty metal is acceptable though. I always derust to the fullest extent possible before moving to sealing. Typically sealing is not needed if properly derusted though. Exception to this rule is if the rust is deep and has eaten through a significant portion of the metal. Sealing in those instances is best. To derust I use phosphoric acid. The same stuff that comes in the tank cleaning/sealing kits that are sold. Kleenstrip Etch and Prep from Home Depot is the stuff. You need to keep the metal surface coated by rotating the tank and sloshing the stuff around. It can be diluted too, it works just fine only slower. The left over can be saved for reuse and then rinse the tank out with clean water followed quickly with some alcohol to help drying and some WD-40 or similar oil to reduce/eliminate flash rust. Skip the last step if you are going to seal of course. No oil allowed.

My tank leaked like a sock would lol. I didn't mean just clean the tank out with soap and water and redkote it. I got as much of the rust out as I could using vinegar and mechanical means. With vinegar, once you rinse it out flash rust is immediate as soon as the water dries. It's an absolute must there is no moisture left in the tank also. I put 2 coats of the redkote in a week apart and let it cure for close to a month and i'd put money on it a pocket knife wouldn't scratch away the redkote over the flash rust. I wouldn't go about using redkote on rust flakes though you absolutely have to get all of the flakes out but flash rust in my experience acts as a primer of sorts giving the sealant something to bond to. I have to disagree with your statement of redkote not being able to seal properly over rust. I've seen tons of videos of por 15 failing but have yet to find one where redkote failed that wasn't due to operator ignorance such as allowing it to pool or not letting it cure long enough. I've also seen tons of videos of people claiming the redkote failed because it turned the gas reddish although the can says it can do that due to the die used that makes it easy to make sure you coated everything. I've not seen one properly done redkote seal fail though.

[Nessism]

My tank leaked like a sock would lol. I didn't mean just clean the tank out with soap and water and redkote it. I got as much of the rust out as I could using vinegar and mechanical means. With vinegar, once you rinse it out flash rust is immediate as soon as the water dries. It's an absolute must there is no moisture left in the tank also. I put 2 coats of the redkote in a week apart and let it cure for close to a month and i'd put money on it a pocket knife wouldn't scratch away the redkote over the flash rust. I wouldn't go about using redkote on rust flakes though you absolutely have to get all of the flakes out but flash rust in my experience acts as a primer of sorts giving the sealant something to bond to. I have to disagree with your statement of redkote not being able to seal properly over rust. I've seen tons of videos of por 15 failing but have yet to find one where redkote failed that wasn't due to operator ignorance such as allowing it to pool or not letting it cure long enough. I've also seen tons of videos of people claiming the redkote failed because it turned the gas reddish although the can says it can do that due to the die used that makes it easy to make sure you coated everything. I've not seen one properly done redkote seal fail though.

My comments were not specific to you. I've done a fair bit of tank restoration and my comments were generalized.

Some of the tank sealers on the market, such as Caswell's and Por-15, state that they seal over rust. Well, I don't care and would much rather remove as much rust as possible. I've used Por-15 several times and it's wonderful stuff. If you prefer Redcoat that's fine too. To each their own.

When using Por-15 the key is to keep the stuff moving in the tank until it kicks off. I flow it around really well for a good 15 mins or so and then dump out the excess...at least that which comes out fairly easily. When you get to this point there will be still some sealer that will still move inside the tank. I make sure to keep it moving and put down a second layer. The first coat will start to firm up and going right over adds another layer, creating an excellent barrier.

Done well most of the sealers on the market are acceptable. If anything Kreem has the worst reputation but I know guys that have 10 years on their Kreem job and that's not a bad thing.

[wymple]

Red-Kote is all I will use anymore. Tough as a basketball, applies with the consistency of maple syrup and holds all those little rust bits & stuff in sealed suspension. Never had a leak, even where there was a bad seam leak. It's done curing when you can't smell it anymore. If it's odorous, keep waiting. Never waited more than one day, myself.

[leftlostcommonsense]

I've only ever used redkote myself, seen way too many other sealers crack and fail. I'm with wymple lol i think the metal would rust away from the outside before the redkote failed. I'm sure the other sealers work just fine when done correctly but I'd rather use something that leaves room for error. I think where the other coats fail is because they're not flexible like the redkote is and vibration and expansion is what gets them over time not to mention the crap we call gasoline now-a-days.

[limeex2]

I used Metal Rescue, its not cheap but either is a non findable tank and cheaper than having it done by a mechanic. I used 3 gallons at $27/gal and moved the tank in various positions for complete coverage. Zero flashback after rinsing with water. Zero affects on anything else. Looks like brand new inside and rust has never returned. Will remove paint if there is rust under the paint, like around filler neck. But spilled on the tank causes no harm. It can be reused. I dont want any liners in my tank, only a last resort. DO NOT use Kreem. It sucks. Red-Kote and Por-15 seem to work much better. Watch this video, this is what made me use Metal rescue. I used vinegar and water and ended up with more rust than when I started, about had a anxiety attack! I could not find the concentrate like he used which would be much more user friendly.https://www.youtube.com/watch?v=fBQX5v4FmzI