Topic: Tank rust removal.

[Ozzybud]

Good news turned to bad news after treating the CB350F tank with Evapo-Rust. I have included a before and after photo of the inside. I was amazed how clean it got the tank with only soaking  for 3 days.

Then I noticed on the forward edge there was 3 small blisters in the paint. Definitely pin holes coming from the inside out. The outside of the tank is almost flawless with the original paint.

I have some epoxy tank sealer in route. I am hoping to get it sealed up so I can ride it this summer. Does this type of sealer work? I am on the hunt for a decent tank that I can re-paint. Most of the ones on Ebay look worse inside  than mine.

Hopefully the sealer will work for the short term.

[Flyin900]

I use Tech Steel as a great flexible sealer that becomes as solid as steel once set. It can be sanded, filed and worked once it has set hard. It is impervious to gasoline or any diesel etc. I would think that JB Weld makes something close to this. It is a metal epoxy that is workable initially. In the case of Tech Steel it is rock solid in 15 minutes with  a full cure in 1 hr. JB Weld not so much with the quick set up times.
You should be able to use it long term as a pinhole sealant that will not deteriorate with time since I have used it for over a dozen years. I have even rebuilt broken fins on a cylinder or head with a thin wire scaffolding to support the new fin area. It has lasted for years in that set up too.

[Ozzybud]

I use Tech Steel as a great flexible sealer that becomes as solid as steel once set. It can be sanded, filed and worked once it has set hard. It is impervious to gasoline or any diesel etc. I would think that JB Weld makes something close to this. It is a metal epoxy that is workable initially. In the case of Tech Steel it is rock solid in 15 minutes with  a full cure in 1 hr. JB Weld not so much with the quick set up times.
You should be able to use it long term as a pinhole sealant that will not deteriorate with time since I have used it for over a dozen years. I have even rebuilt broken fins on a cylinder or head with a thin wire scaffolding to support the new fin area. It has lasted for years in that set up too.

I am a little hesitant to strip and re finish this tank. I am assuming that the metal is paper thin and with 3 showing now 30 more pinholes are ready to pop through.
I bought some inside of the tank coating (Caswell Epoxy). I am hoping That will seal it up.

[newday777]

Brickhouse Builds on YouTube just did a video on Caswell coating a tank.

[Ozzybud]

Brickhouse Builds on YouTube just did a video on Caswell coating a tank.

Thank you... great video!
Looks like i bought the right product!

[beemerbum]

Good news turned to bad news after treating the CB350F tank with Evapo-Rust. I have included a before and after photo of the inside. I was amazed how clean it got the tank with only soaking  for 3 days.

Then I noticed on the forward edge there was 3 small blisters in the paint. Definitely pin holes coming from the inside out. The outside of the tank is almost flawless with the original paint.

I have some epoxy tank sealer in route. I am hoping to get it sealed up so I can ride it this summer. Does this type of sealer work? I am on the hunt for a decent tank that I can re-paint. Most of the ones on Ebay look worse inside  than mine.

Hopefully the sealer will work for the short term.

How much Evaporust did you put in the tank?

[Ozzybud]

Good news turned to bad news after treating the CB350F tank with Evapo-Rust. I have included a before and after photo of the inside. I was amazed how clean it got the tank with only soaking  for 3 days.

Then I noticed on the forward edge there was 3 small blisters in the paint. Definitely pin holes coming from the inside out. The outside of the tank is almost flawless with the original paint.

I have some epoxy tank sealer in route. I am hoping to get it sealed up so I can ride it this summer. Does this type of sealer work? I am on the hunt for a decent tank that I can re-paint. Most of the ones on Ebay look worse inside  than mine.

100 percent full 3+gallons

Hopefully the sealer will work for the short term.

How much Evaporust did you put in the tank?

100 percent full 3+ gallons.

[newday777]

Brickhouse Builds on YouTube just did a video on Caswell coating a tank.

Thank you... great video!
Looks like i bought the right product!

You are welcome. I just saw it last night.

[Flyin900]

I am a little hesitant to strip and re finish this tank. I am assuming that the metal is paper thin and with 3 showing now 30 more pinholes are ready to pop through.
I bought some inside of the tank coating (Caswell Epoxy). I am hoping That will seal it up.
[/quote]


The Caswells makes better sense for the pin holes in the upper area of your tank. I suspected it was the seam or bottom area of the tank where they are mostly evident on many tanks.

FYI on the Caswells I found it a very thick consistency and poorly coating of the entire tank area easily when the tank was rolled around. I recommend using a thinner as noted in the instructions to thin and allow the material to flow around the interior of the tank easier. Acetone works very well as the thinner for this purpose.

[seanbarney41]

+1 on thinning it...I used it once an did not and it was very difficult to get it everywhere inside.  If you don't get full coverage the gas can get underneath and ruin the lining

[Kelly E]

I have heard many good things about POR-15 tank sealer. It comes with the needed prep cleaners for proper adhesion.

[jaytee-nz]

I've used POR15 many times and it works really well - BUT you must follow their instructions to the letter, especially about the tank being 100% dry before putting the lining product in. It's easy to think it is dry after a few hours but if you check the inside seams, they hold moisture and it takes many, many hours of blowing a heat gun in there to completely dry it out.

[CycleRanger]

I've used POR15 many times and it works really well - BUT you must follow their instructions to the letter, especially about the tank being 100% dry before putting the lining product in. It's easy to think it is dry after a few hours but if you check the inside seams, they hold moisture and it takes many, many hours of blowing a heat gun in there to completely dry it out.

Same, I've used it twice. Good results.

[Ozzybud]

I've used POR15 many times and it works really well - BUT you must follow their instructions to the letter, especially about the tank being 100% dry before putting the lining product in. It's easy to think it is dry after a few hours but if you check the inside seams, they hold moisture and it takes many, many hours of blowing a heat gun in there to completely dry it out.

I am going to use the Caswell system as i have it in my possession. i flushed it thoroughly 3 days ago 3 times with Acetone going to wait a few more until i do the application... keeping my shop 75-80° in preparation.

[RAFster122s]

The seams are critical to be dry before you seal up the tank no matter what liner you use. Trapping moisture leads to very bad results when that moisture causes rust and seal failure.
The POR product reacts with water flash curing and that is a week currently, it doesn't combine with all the water, leading to seam failure...

So, warm that tank up plenty to drive out the moisture in your prep.

Caswell is a good product, as is the POR...

[Don R]

 I did a Fibermold tank with Caswell, it is an old custom fiberglass tank. It holds 3 gallons tank and I had the large kit, so I mixed half of it. I could actually see the product flow through the bottom of the gel fiberglass and knew it was too thick so I mixed the second half of the kit and dumped it all in, thinned a little. I was able to get awesome coverage.
 Caswell is also able to protect the old fiberglass from alcohol.

[seanbarney41]

I did a Fibermold tank with Caswell, it is an old custom fiberglass tank. It holds 3 gallons tank and I had the large kit, so I mixed half of it. I could actually see the product flow through the bottom of the gel fiberglass and knew it was too thick so I mixed the second half of the kit and dumped it all in, thinned a little. I was able to get awesome coverage.
 Caswell is also able to protect the old fiberglass from alcohol.

I also have one of those tanks and another much larger Reed  Titan tank that both need lining.  How much have you actually used your Fibremold tank, Don?

[Ozzybud]

Got the tank sealed this morning with the Caswell Clear Epoxy liner. Went very well. Rolled the tank around for 25 minutes.
Rebuilt Kehin petcock and new repo cap
I'll give it a few days before adding gas.
I have high hopes!

[Stev-o]

Rebuilt Kehin petcock and new repo cap

Keihin makes petcocks? 

[Ozzybud]

Rebuilt Kehin petcock and new repo cap

Keihin makes petcocks?

I rebuilt  mine. The original is made by Keihin.  At least it has a huge "K" like the jets on the strainer cap

[Cevan]

Ozzy, how did you keep the sealant from getting in the threads in petcock area?  I'm referring to the 2 M6 screws that secure the petcock to the tank. 

[Ozzybud]

7
Ozzy, how did you keep the sealant from getting in the threads in petcock area?  I'm referring to the 2 M6 screws that secure the petcock to the tank.

I used 2 bolts that just protruded the same length as the factory screws, I coated them with a touch of wax.i used a simple rubber plug to plug the center hole.

I then drained the majority of the excess which was only a couple ounces at the 35 minute mark from the filler i then pulled the rubber plug and drained the rest from the bottom.

At about 3 hours I removed the screws and used a small file to open up the center hole to the factory size.leaving a little bit of the coating around the edges.

[Ozzybud]

Rebuilt Kehin petcock and new repo cap

Keihin makes petcocks?

I rebuilt  mine. The original is made by Keihin.  At least it has a huge "K" like the jets on the strainer cap

I thought Keihin manufactured all the petcocks?  Most do not have enough real estate to display their Logo.
The same logo is on my other bikes with  Strainers!

[Flyin900]

Got the tank sealed this morning with the Caswell Clear Epoxy liner. Went very well. Rolled the tank around for 25 minutes.
Rebuilt Kehin petcock and new repo cap
I'll give it a few days before adding gas.
I have high hopes!

Did you have to thin the material, or was it more runny as received??

[Ozzybud]

Got the tank sealed this morning with the Caswell Clear Epoxy liner. Went very well. Rolled the tank around for 25 minutes.
Rebuilt Kehin petcock and new repo cap
I'll give it a few days before adding gas.
I have high hopes!

Did you have to thin the material, or was it more runny as received??

It was the thick type!  I used 1oz of thinner. It was still very thick but i didn't want it to be runny. It moved around in the tank just fine. 100 percent coverage was accomplished for sure!  I had my shop and the product at 80 degrees.

[Stev-o]

Rebuilt Kehin petcock and new repo cap

Keihin makes petcocks?

I rebuilt  mine. The original is made by Keihin.  At least it has a huge "K" like the jets on the strainer cap

I thought Keihin manufactured all the petcocks?  Most do not have enough real estate to display their Logo.
The same logo is on my other bikes with  Strainers!

I believe you are correct. I never noticed the logo or even thought about it.  Learned something new...thx

[rotortiller]

Thinning epoxy with a solvent changes it's properties negatively.  Too much thinner and it can shrink, crack, and lift at a later date. Most epoxy vendors do not recommend solvent thinners, specifically cautioning against them. POR tank sealer comes out of the can in a suitable thickness. Depending on cure time, the tank and epoxy could be heated to thin it out without bad #$%* happening later down the road. Both POR and epoxy may be mucked up in the right hands. In my experience those hands are usually attached the same body as the vocal cords cursing tank liners.

[Don R]

 As always, read and follow label directions, few folks know the properties of a product better than the people that make it.
 My buddy advised an automotive customer with a long-neglected car to put three cap fulls of Seafoam into his crankcase oil, the guy wasn't listening, didn't read the directions and dumped three cans in. Predictable results.

[Don R]

 I saw pics on Facebook where a guy did electrolysis on his rusty tank, he inserted the electrode into a plastic tube with large holes in it that acted as an insulator to keep it from grounding to the tank yet exposed the wire to the soda electrolyte.  Seemed like a good idea.
 You might even be able to heat the plastic tube and bend it to make itself support inside the tank and keep it closer to where you want it.

[Ozzybud]

Thinning epoxy with a solvent changes it's properties negatively.  Too much thinner and it can shrink, crack, and lift at a later date. Most epoxy vendors do not recommend solvent thinners, specifically cautioning against them. POR tank sealer comes out of the can in a suitable thickness. Depending on cure time, the tank and epoxy could be heated to thin it out without bad #$%* happening later down the road. Both POR and epoxy may be mucked up in the right hands. In my experience those hands are usually attached the same body as the vocal cords cursing tank liners.

Followed instructions that said to thin it!
See Pic attatched

I have been painting cars and bikes most of my life and we always thin epoxy primers. The new replacement for DP 90  is DP90LF it's the same stuff except legally they could not say to thin it on the Tech sheets as it would no longer be VOC compliant if you added thinner. For use as a seal coat before basecoat it's a must to thin it.

[Ozzybud]

Positive update!

Filled it with fresh non ethanol premium. No leaks!
Took it for a cold PNW 15 mile ride. These 350F's are a blast to ride.

[Ozzybud]

Forgot to mention when cleaning I ordered
a 12 pack of Jack's on Amazon. They worked well to lightly abrade the inside and were easy to remove. Along with some hardware held together with a bailing wire ring.

[BenelliSEI]

“I rebuilt  mine. The original is made by Keihin.  At least it has a huge "K" like the jets on the strainer cap”
« Last Edit: January 23, 2025, 11:57:28 AM by Ozzybud »

Funny…. I’ve looked at that stamping +100’s of times and never connected the dots!  Thanks…..

[RAFster122s]

Section of light chain works on knocking loose scaly rust inside a tank and is easy to fish out afterwards...

[Ozzybud]

“I rebuilt  mine. The original is made by Keihin.  At least it has a huge "K" like the jets on the strainer cap”
« Last Edit: January 23, 2025, 11:57:28 AM by Ozzybud »

Funny…. I’ve looked at that stamping +100’s of times and never connected the dots!  Thanks…..

Honda did a great job farming out sub assemblies to other companies.
Keihin,Nippn Seiki,Nippon Denso,Sankei . I am sure there are others.

[rotortiller]

Food for thought.

https://www.epoxyworks.com/thinning-west-system-epoxy/

[Ozzybud]

I bought this not so lovely tank( on the outside) on ebay for relatively cheap.
The good part is the inside is absolutly spotless. See picture below.
I'll be sanding most of the surface rust out.
1. Conversion coating
2. Epoxy primer
3. Primer surfacer
4. Silver basecoat
5. Candy flake matador red midcoat
6. Clearcoat
7. Sand/ polish
8. Apply decals
Going to do my best to match the side covers and other pieces In the bike. This will include doing some test panels first

[RAFster122s]

Looks like that would be a good candidate for electrolysis to remove the rust and deposit good steel in its place so it isn't any thinner.

[Ozzybud]

Looks like that would be a good candidate for electrolysis to remove the rust and deposit good steel in its place so it isn't any thinner.

It's just surface rust.  Looks worse than it is.  There is no deep pitting.

The conversIon coating I use is Rust Mort(phosphoric acid) it wil stabilize any remaining rust and encapsulate it under the Epoxy Primer