Topic: CB400F cam chain housing damage & rusty fork legs

[The Lone Builder]

Having some time on my hands, and waiting on some parts fro the 750, I’ve started work on the 400F I acquired last year. It’s a late model F2 and it’s rougher than I at first thought and I mow pondering whether to just get it going and ride or to spend more time and money on a more thorough job. I’m inclined, at present towards the riding option.

One thing I discovered today is damage to the cam chain adjuster housing on the crankcase. The adjuster bolt is missing and the hole has been plugged with something. What are my options here?

Is there a way to repair it properly? Would this involve a complete engine dismantle? Can I leave it as is? Or do I need new cases?

The fork legs are also badly rusted. The top is much worse than the bottom; there is some pitting which is generally not too deep. Can I smooth it out and go? Or do I need a new set? Sorry the pic is more of the top than the bottom.

Thanks for your thoughts.

[robvangulik]

Mine was approx the same when I got it, cleaned it up and have been riding for the last 12 years without leaking

[The Lone Builder]

Are you referring to the rust or the cam chain housing?

How did you get rid of the rust? Was it just superficial, or deeper? The rust on mine, esp wheels and swinging arm is pretty bad.

[Bodi]

I would replace the fork tubes. You can try and smooth them out but the pits will most likely ruin the seals pretty quickly. The CB350-Four uses the same tubes, possibly the CB350/360 (disk brake models) twins as well but I don't think so - both are 33mm and use the same disk brake caliper and mount, but may have other differences.
The cam chain adjuster area is a mess. Looks to me like a PO broke off the lock bolt, did something to get the remains out to unlock the rod, and then closed off the hole with epoxy. Then put a pusher bolt in the top hole to tension the cam chain. That works OK and is not really a problem, assuming the horseshoe pivot is not damaged from a very loose chain.
The question is ... what was done to remove the broken lock bolt? If it's really been butchered there are repair options but you need to split the cases to get good access. If the stub was removed without ruining the 6mm case threads or the adjuster rod, you just need to clean the hole out and get a replacement lock bolt (a rather odd bolt with 6mm and 8mm threads). These bolts would be broken off fairly often because the 12mm head and visible 8mm threads and locknut invite overtightening - breaking off the 6mm end that threads into the case.
You will need to get that glob of epoxy or whatever off and clean out the hole to see what you're dealing with.
You can just leave it as is if you can adjust the cam chain tension with whatever is in the upper hole.