introduction

[Stevo]

Hi peeps,
I am a lifelong biker and have just bought a crusty old 1975 cb400f super sport, my first step is to give it a good clean and then see if I can get a tune out of it with a view to riding it over the winter.
It does have an unusual locking petrol cap mechanism that needs some kind of hollow hex key to operate, David Silver was not able to shed any light on it, I was wondering if any of you guys knew about such a thing, it is a standard tank and all looks standard ?
Cheers all.
Steve.
username stevo.

[Johnny4428]

Hi Stevo, welcome to the forum, most of us softies are tucking our classics away for the winter (or maybe it’s just me)🤣 no experience with these locking caps but I’m quite sure there are people here that are. Good luck with the bike!

[Orcade-Ian]

Hi Steve,
Welcome to this great forum, I've had quite a few 400/4's but have not seen a lock like you describe.  A few pics might lead us to a conclusion but if its just a hollow hex, then I'm sure something will turn up.  I have some different sizes of hex bar - mostly imperial unfortunately but perhaps something close could be drilled - assuming i'm understanding correctly, I could probably make something.

Ian

Hollow allen keys are available for security screws too!

[Oddjob]

It's an old 80s design to stop people opening the tank to nick your fuel. It's a sort of reverse allen key, I did have one of those actual locks NOS in my stash, not sure if the key is with it though. Might even have a NOS normal key lock as well.

[Bryanj]

The " normal"  key lock is the one the yank insisted was retrofitted to all the fours, any key fits and i think its still available from honda

[McCabe-Thiele (Ted)]

Welcome Steve plenty of current/past 400 owners here.
Not many issues that one or more of us have not experienced & sorted  plus lots on new & used parts available in the UK.

[Athame57]

Hi Steve
Welcome here, good luck with the 400, they are lovely bikes!

[Stevo]

Thank you all for such warm and lively welcome.
All the very best.
Steve.

[Multiman]

Hi Steve,
welcome to the forum.
I am also a 400/4 owner and not so far from you.
I live near Corsham.
Hope you get it sorted ok.
Cheers
Tim

[Laverdaroo]

Ehyup Stevo,

Welcome to the forum and congrats on the new bike. If you cant find the info you'll be looking for here then you're on the wrong site
I've a 400 too and Tim's not far from me, also there's Andy quite close by in Bristol (Comfy Sofa) and Bryan isn't too far either so you're surrounded by help should you need it. There's a few parts lurking between us too so if you're stuck, please shout

|Good luck

[philward]

Welcome to the forum Stevo - enjoy the forum and your new bike

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[Stevo]

Hey thank you all for your encouragement, started stripping the motor, been standing for 37 years so seized solid, had to cut cam chain to get the cam out and the head off, filled bores with 50/50 ATF/Acetone, went around barrel with blow torch to gently warm till fluid started to heat up then left 24hrs, repeated this three times with persistent tapping of pistons with wooden drift and I won !. barrel is now off and ready for glaze busting.
I am going to source valve guide seals, gaskets, one short head stud and copper washer for now.
I will clean the carbs in my ultrasonic cleaner and clean off the decades of crud from everything else, the chromework is toast.
I will also be looking for an exhaust as this was the only item missing from the bike.
I will keep you all posted.
cheers peeps.
steve.

[McCabe-Thiele (Ted)]

My 400 was not sized when purchase but had stood for 12 years - bores needed a rebore well beyond glaze breaking.

Trigger a member here did my rebore during lock down - a well respected engineer - not sure if he has fully retired though.

My Carb sliders were seized solid took a few days before they moved.

[SteveD CB500K0]

Start a new thread in the Projects section Steve.

Just my “keep tidy” OCD

Steve


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