Fuel Tank Clean

Hey Guys,
Should I Evapo-Rust this tank or wait?  Process seems like a PITA. See pics. Tanks on a KZ1000J3. I believe this product is paint safe - tanks a repaint of an NOS tank that was put on the bike 15 years ago.  Any knowledge of this? 

Two mechanics said see how it progresses and wait. Fuel is still clean. Carbs were just cleaned and there were no rust deposits found. Your thoughts? Evapo-Rust has a low ph and apparently does not effect the hot dip galvanized surface in the tank but with the minor nature of what I am seeing even after a treatment I am thinking the metal will be a little more compromised  and there could be more flash rust on the short/long term than what i see now even with a full tank of gas and Stabil.  Also if I went ahead with this now, what is the best way to  close off the oval fuel sender and  petcock holes so not to get leaks? 
Thanks in advance.
 

From what you have shown in the photos, I would wait. Evapo-rust works well but at this stage, you may not need it. 

Thanks Michael. Remember you back at KZ1000r.com.  Hope your well.

I wish my fuel tanks were that clean.

Vintage3 wrote:

Hey Guys,
... Evapo-Rust has a low ph and apparently does not effect the hot dip galvanized surface in the tank ...




 

Hi Vintage3,
The inside of the tank is raw steel.
If you do clean the tank a good way to avoid flash rust is described here:
kzrider.com/articles/219-technical-tips/22-rusty-tanks
All I'd do for that tank is install a fuel filter.
I recently repurposed a rotational molder into a Tank Tumbler.
You'll find a video of it in action here: 
www.kzrider.com/forum/13-bike-related/62...ning?start=12#906658
Bill/KZQ

How does the tank look lower down?  Personally, I'd do the Evaporust treatment.  Done it on several tanks.  Be ready with a quart of IA and some WD-40 after rinsing, to stop any flash rust.  

For tanks with more rust, I'd use phosphoric acid.  This tank isn't very bad, though.  And Evaporust won't hurt paint, if you spill the sauce during the process.

One thing, always remove the petcock, and any extra fuel sending units or fuel level sensor units.  Fashion blank off plates, and a plug in place of the fuel cap.  Never use the factory devices, they will get damaged.  And that includes Evaporust.  It eats off zinc plating.

Thanks. The bottom of the tank looks similar with alot more silver in view than rust. I didn't know about Evapo Rust removing the zinc coating which I gather has a benefit to preventing rust in the first place. I feel it's almost counter intuitive to treat it and wait and try to minimize the rust as it will suddenly become more suseptable to corrosion with the coating removed (I think this is correct?) Is there a safer way to clean the tank that will not harm the zinc coating and the repaint (not oem)?

Anyone use Marvel's Mystery Oil?  I understand it can be used with Stabil and people claim it leaves the tank with a higher level of protection against this sort of thing  as it leaves an oily film on the metal? Also in the owners manual it says for winter and long term storage to add some oil to the tank and swish it around for winter and long term storage and in spring just add gas and drive. This seems to be an old school way of doing things especially for winter storage as all I hear is people filling there tanks and adding Stabil to them. The bike is heat stored, topped with gas and Stabil in the winter.

The tank doesn't look  to bad but I would also go with Evaporust treatment 

Ditto Ckahleer's thoughts, that's Really nice to start with! But looking merely down from the top means waay less then peering down where everything settles, lower rear, both sides as Nessism mentioned. A little surface isn't going to hurt anything or even a bit more. What IS Important is your petcock sock/filter! Look for tears/rotting in oval screen, especially the lower section. If it all looks as nice as your pictures provided i wouldn't waste my time doing anything.    

I used muriatic acid. then compressed air. then fogging oil. but wouldn't have a problem using evaporust. tank had been repainted w modern paint and urethane clearcoat. no idea how the acid would affect old paint.

Muriatic acid, or HCl, hydrochloric acid, is the strongest commonly available.  I would never use this to derust a gas tank.  It's way too harsh.  Professional painters and such use phosphoric acid.  Quite effective, but far less harsh, and it doesn't need to be neutralized either.

The pics you posted look great to my old eyes. But as others have said it is the bottom and back of the tank that needs to be viewed. A telescopic mirror and flash lite can aid in this. As an aside, not like I have cleaned huge number of tanks but have done several via electrolysis. All needed is a battery charger, some soap powder. water (hot.warm works faster) and a piece of steel. I have used threaded rod and covered it in fiberglass/ nylon window screen with great success.