Topic: Nastiest fuel tank

[1st timer]

Men and women, boys and girls,  yikes.   The internals of the tank on my newly acquired 75' CB400f is that nastiest I've ever seen (and that's a lot).  But before I go and start pouring some acid into it to clean and de-rust it a bit, I require a piece of advice.

How does one safely (read without damage)  remove the chrome gas cap??  The cap itself will most likely be cleaned in a nice ultrasonic bath.  And I'd like to get it out of the way for capping purposes during both acid wash and POR 15 treatment.

I sincerely thank you for any advice you may be able to provide.  Max

[CB650CPastor]

Looks like you've got to remove the pin. Without seeing it, I can't tell you how. If it's riveted, you'll have to drill out the rivet and then get another pin to replace it like the pin in this kit:

http://www.ebay.com/itm/NEW-GAS-TANK-CAP-PIN-LATCH-HONDA-CB350F-CB400F-CB500-CB550-67-68-69-70-71-72-73-/140871191260

[carnivorous chicken]

It's a pin that is expanded on both ends. Drilling it's easy, I've never tried to do it and not ruin the pin. Might be able to tap it through.

[Powderman]

My parts list shows the 75 CB400F has the screw on cap with the hinged cover that come off with 2 screws. It doesn't have the same flip cap like the 74 CB350f.
75 CB400F should have the same cap as my 77:




You'll notice the link below says CB350, CB400, CB500, CB550. But also says 67-73.
I would recommend Caswells new sealer over any other.

[1st timer]

Thank you all.  Here a couple photos of the cap.  I picked this beauty up at an auction last Oct.  And indeed it is my first Honda.  I've had and still have Ossa's, Ducati's, Yammis, HD, BMW.  The list goes on.  But simply never had a Honda before.  And while this thing is externally sweet, the carbs and gas tank are some the worst I've seen.

Now onto the advice.  Just how long a Drill bit am I going to need to drill out the pins without damaging the tank?  Thanks again.

Sorry!  How does one post a photos here??

[mystic_1]

Not much.  The factory pin was installed by flaring one end, rivet-style.  This is the end you'll "drill out", by which what you're really doing is removing enough metal to remove the flared portion of the pin.

Sort of like this.




Now, the cas cap hinge pins are pretty small and the flared area is pretty thin, so I've found that you don't really need to drill all that deep, not even deep enough to separate the flared material, just enough to weaken it.  Then, as you drive the pin through the hole (I use a spring-powered center punch) the flared edges will tend to fold back in as you push the pin out.

If you're really lucky, you can get the pin out with enough material left on it to reinstall it and re-flare it.  Replacement pins are out there, though, or you could replace with small threaded hardware, so you don't necessarily need to be this careful, but still it's possible.



The one reason why you might need a long drill bit is so that you can get at the pin at a good angle, if your drill's body hits the tank when you try to get at the pin.

mystic_1

[strynboen]

euro modells have only the cap. type    .us(later) modells have the door/clap type..

[mystic_1]

On at least one occasion, I was able to drive a pin out without drilling it at all.  I just used the spring loaded center punch, put it into the dimple in the flared end of the pin, and gave it a few hits.  The metal of the flared area was thin enough already for it to unfold itself as I drove the pin through the hole.  Once I'd driven the pin through enough to grip it with needle nose pliers from the other side, I gripped the pin and then tapped the pliers with a hammer to pull the pin the rest of the way out.

mystic_1

[strynboen]

yes i just carefull hannered the pin aut...it is not a rivet..more a pin..but the" one end" is smaller..and hammer in the small end ind frees it all up

[carnivorous chicken]

My parts list shows the 75 CB400F has the screw on cap with the hinged cover that come off with 2 screws. It doesn't have the same flip cap like the 74 CB350f.
75 CB400F should have the same cap as my 77:
You'll notice the link below says CB350, CB400, CB500, CB550. But also says 67-73.
I would recommend Caswells new sealer over any other.

Just for the record, some if not most 1975 CB400F bikes came with the standard flip cap like the 350F, not the hinged door. The Honda parts fiche for the 1975 Honda CB400F indeed shows the hinged door/cap, but the four that I've owned over the years have all had the standard hinged cap without the door. Dunno when/why the change was made, curious if anyone else knows, but likely through the middle or end of the 1975 production run. By the next year's model, they were all hinged doors style.

[carnivorous chicken]

My parts list shows the 75 CB400F has the screw on cap with the hinged cover that come off with 2 screws. It doesn't have the same flip cap like the 74 CB350f.
75 CB400F should have the same cap as my 77:
You'll notice the link below says CB350, CB400, CB500, CB550. But also says 67-73.
I would recommend Caswells new sealer over any other.

Just for the record, some if not most 1975 CB400F bikes (in the US at least) came with the standard flip cap like the 350F, not the hinged door. The Honda parts fiche for the 1975 Honda CB400F indeed shows the hinged door/cap, but the four that I've owned over the years have all had the standard hinged cap without the door. This is also verified by a google image search. Dunno when/why the change was made, curious if anyone else knows, but likely through the middle or end of the 1975 production run. By the next year's model, they were all hinged doors style.

[carnivorous chicken]

Not much.  The factory pin was installed by flaring one end, rivet-style.  This is the end you'll "drill out", by which what you're really doing is removing enough metal to remove the flared portion of the pin.

Sort of like this.




Now, the cas cap hinge pins are pretty small and the flared area is pretty thin, so I've found that you don't really need to drill all that deep, not even deep enough to separate the flared material, just enough to weaken it.  Then, as you drive the pin through the hole (I use a spring-powered center punch) the flared edges will tend to fold back in as you push the pin out.

If you're really lucky, you can get the pin out with enough material left on it to reinstall it and re-flare it.  Replacement pins are out there, though, or you could replace with small threaded hardware, so you don't necessarily need to be this careful, but still it's possible.



The one reason why you might need a long drill bit is so that you can get at the pin at a good angle, if your drill's body hits the tank when you try to get at the pin.

mystic_1

This, although reusing the pin is optimistic I think. That being said, I recall reusing one that I had drilled out, and although I couldn't re-flare the end of the pin, it stayed in place.

[CB650CPastor]

Sorry!  How does one post a photos here??

To post photos, you have to upload them to a photo-hosting site and then insert links to them here.

[CB650CPastor]

Hondaman sells pins. Not sure if this fits your bike, but it's a place to start anyway. Just a bolt with washers and an acorn nut.

http://sohc4shop.com/catalog/product_info.php?cPath=25&products_id=38

[vames]

On my 75 CB400f i gently tapped the old pin out with a punch and used Hondaman's threaded pin when I put it back together.

http://sohc4shop.com/catalog/product_info.php?manufacturers_id=12&products_id=38&osCsid=953a968ac3a05decc87367d5fe10d008


Bonus is that Hondaman gives all the proceeds back to www.sohc4.net for these.