Reviving Honda gas caps

[Jd110]

First off, soak it down with a penetrant on the inside so the parts separate nicely. Next, mark or remember the two pieces so they go back the same. https://uploads.tapatalk-cdn.com/20250524/7dbe234dbc6c387d456de90ff0f4ed59.jpg
To open it, bend the low spots about half way around on the outer part, just barely.
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Don’t loose order of the parts and how they go or it won’t work. That little plastic ‘button’ that goes on top of the spring and tiny oring has a number on it that faces up. Save that oring and big rubber washer.
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Apple cider vinegar takes less than 24hrs to eliminate most of the rust. It will want to flash rust when it comes out, so be ready to dry it off with a rag followed by blow dry. Steel wool will clean what’s left.
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If you have a sandblaster, that is better. It won’t flash rust.
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To remove the on/off knob, just pull the metal piece on the back side. It is peened onto the shaft. There is a small oring that will most likely need replacing.
https://uploads.tapatalk-cdn.com/20250524/c733cce99ef5f27a3ad89f5a86a4a83b.jpg
The other rubber pieces will likely be ok.
https://uploads.tapatalk-cdn.com/20250524/bd3acfe05d587bef8f5b3cce301181b6.jpg
Knocker loose works better than vinegar to clean rust off rubber.
https://uploads.tapatalk-cdn.com/20250524/05025027978ec7c23ccf04d72d2b4990.jpg
Freshen the rubber up with liquid silicone.
https://uploads.tapatalk-cdn.com/20250524/210d197c3862ec7c166ebffb25468f75.jpg
I’m painting them because it is easier than zinc and better than the rust.
We’ll put them back together soon.https://uploads.tapatalk-cdn.com/20250525/48d3aed60d2ce7dd1b199c7b2964d985.jpg

[Jd110]

I had semi gloss engine paint that is supposed to be resistant to ‘chemicals’. I’m soaking some painted parts in gas to see. I don’t want these caps opened up for long, so testing them in gas will be a couple days.
I also have some 93% zinc paint but I’m not sure it will hold up so I might have to test that, also.
Basically, I may need to plate these or have someone do it for me. Awl be back…;)
https://uploads.tapatalk-cdn.com/20250525/0e83f7766458cfc548b88c91a20c4c8d.jpg

[Jd110]

The paint is holding up fine. It’s dupli-color engine paint. I heat treated it a few times. https://uploads.tapatalk-cdn.com/20250526/d03533ef4da7b5019ec30fc4f11147a0.jpg
https://uploads.tapatalk-cdn.com/20250526/bf6100f06293272f612fa2cad0ed95fe.jpg
I wouldn’t be afraid to leave them painted or even powered might work well. But I’m going to strip them down again and plate them with zinc.
I made a tool to get the spring out. Push down on spring and remove center bar. https://uploads.tapatalk-cdn.com/20250526/0b7663cd2e331ed8b1bf76915d33fc98.jpg
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I believe 85’ and maybe 86’/87 have the plastic cup with one way rubber valve. Here’s how to remove that:
https://uploads.tapatalk-cdn.com/20250526/c0d3aae9e5648640edb98422d26f6b5e.jpg
Use a screwdriver to push down on one half of the spring. While doing that move the cup ‘holder’ in the direction you are holding the spring. It should ride on top of that half and pop out of the other side. https://uploads.tapatalk-cdn.com/20250526/8f5d68bfead7e12280218c5d695ffadd.jpg

https://uploads.tapatalk-cdn.com/20250526/e69e953763d61798c1c6ff0e7cab905a.jpg

[camy]

that is a good how to!!! :naughty:

[Jd110]

https://uploads.tapatalk-cdn.com/20250608/404fccabde2c11dc6768045d250403ee.jpg
To assemble you can start by placing the oring on the underside of the cap. It needs to fit snug around the on/off knob and fit inside center recess.
https://uploads.tapatalk-cdn.com/20250608/4fccc9a6027a604545e969b2dad90a13.jpg
Push the knob through cap and oring.
https://uploads.tapatalk-cdn.com/20250608/d05eaa2293b6a1d628b299e507a796f1.jpg
Metal dish followed by the spring.
https://uploads.tapatalk-cdn.com/20250608/83d2d70d755a319516be9d2db70893b9.jpg
This last metal piece should snap by on but you can peen it again.
https://uploads.tapatalk-cdn.com/20250608/a71f9f7956b73e97c7a2bf0afcadf06a.jpg
Just like removal-hold down one half of the spring while placing the ‘cup holder’ into one hole. The first half needs to ride up onto the spring then just push down on the other side and slip it into the other hole.
https://uploads.tapatalk-cdn.com/20250608/8fc1833f396c21f90ae57386c8a58011.jpg
Install cup holder and big rubber washer.
https://uploads.tapatalk-cdn.com/20250608/99b790026e6a5490ae1a4a05296b389b.jpg
Oring in place, make note of this notch. It lines up with the inside tit.
https://uploads.tapatalk-cdn.com/20250608/17cc4c7ab316a4696ece14368d542c75.jpg

This little oring is especially tall for its size but the spring is obviously going to be taller. Oring first then spring is centered on another little tit.
https://uploads.tapatalk-cdn.com/20250608/c94a2844cac8210fdc6e1a2fd1f8e49c.jpg
Button is placed with the number facing up.
https://uploads.tapatalk-cdn.com/20250608/91264bc0d8f322338370d4e193601729.jpg
With knob off, line the bottom up with the lowest spot on the plastic thing (receiver).
https://uploads.tapatalk-cdn.com/20250608/fae9fddfae634aa08bc011617e9f2a0d.jpg
Hold it for now until the next step.

[Jd110]

https://uploads.tapatalk-cdn.com/20250608/c36a0d7a474d6a1760382e6ecfadc1a9.jpg
To close it up I took a brass punch with rounded edges, to keep from marring the metal. Just a couple little taps on a 45 degree angle. You want the punch to slip off the edge to help close the gap.
https://uploads.tapatalk-cdn.com/20250608/8868db6d11d5adeb78b5451b9a15502e.jpg
Do that all the way around in a vise with soft jaws. Very little force in the vise. It’s just to hold it there while you are tapping on it.
https://uploads.tapatalk-cdn.com/20250608/294f724cfd53dc8e4c5b90a4646975a7.jpg
If you are worried about the paint, go to your rubber/plastic stash you’ve been saving and cap your punch.
https://uploads.tapatalk-cdn.com/20250608/3fd534dc71282b62636b9bf0d92fc45b.jpg
That is it. I’ll get mine finished soon, I hope.

[shortline10]

Great job and tutorial .
I believe I still have a NOS one of these .

[ATC King]

Am I correct the aftermarket fuel caps don't have a closable vent?

I always liked that feature, when they're stored in an enclosed area during higher temps, so the place doesn't smell like a spark will renovate it. I don't know how well they seal, but it would also potentially keep it from pressure cycling during night and day, pushing out vapors during the day, then cooling off at night an pulling in moisture with the air.

People don't think about it anymore, but before EVAP systems on automobiles, the fuel caps just vented to atmosphere. Yes, that's bad for the environment, but also bad for the vehicle, especially since they had metal fuel tanks. They also lost fuel just sitting there, through vaporization.

Anyone who has watched a sealed, plastic fuel container throughout the day is aware of it. It physically expands during the day, and in the early morning it will show signs of collapse, container walls pulled inwards. That doesn't affect a lot of people, as they just let their cans sit around without a cap, then wonder how water got in the fuel. The old style metal cans with the spring loaded cap are a bit of a pain, but it keeps lazy people from ruining fuel, if those types of people are around to cause concern.


Thanks for all the work and posting pictures. I'd rather spend the time doing all that than using one of the smooth top caps, especially on a metal tank.

As a note, some may wonder what keeps fuel from spilling out the vent if the machine is laid over. There is usually a check ball in the aftermarket plastic caps, that simply falls with gravity to seal the vent if tipped over, and covers the vent hole. If there's a rattle when shaking an aftermarket cap, that's the check ball. It looks like the OE ES cap may be using that plastic disc and O-ring, and is a one-way valve. If that's the case, it shouldn't vent outwardly, but it could still pull in moisture laden air at night, hence why closing the vent would prevent water contamination of the fuel.

Air always has to fill the tank as the fuel level drops, or a vacuum forms and the fuel won't drain out into the carb. That would mean the OE valve function can be tested. If riding with it closed, then the engine stalls, the valve is working. If it doesn't stall, then it needs repaired and this thread referenced.

[Jd110]

Hey now, thanks for the feedback and kind words from you guys.
I think this site and everyone associated with 3-wheelers-the true trike enthusiasts-fuel the fire and keep us caring for our machines.
Heck, I’m probably messing with caps that were cared for by someone who converted to a 4-wheeler. Because honestly these caps and tanks I have that came with the caps have been grossly neglected.
Thanks again