Author Topic: New (to me!) '77 CB400F - US model  (Read 38159 times)

Offline mattsz

  • SOHC Pro
  • Posts: 606
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #315 on: April 14, 2020, 06:22:08 PM »
Looking at your re-adjusted carbs with the chokes open is about right.  As Taysidedragon mentions, they are normally open 95% of the time so that is where you want the adjustment to count.  As an aside, when I start my bike on full choke I have to open the choke a fair amount once the engine has started otherwise it races up to 3000RPM.

The spec for that fast idle setting appears to be 3500 - 4500 rpm... seems quite high to me, but Honda must know what they're up to...

Offline mattsz

  • SOHC Pro
  • Posts: 606
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #316 on: April 15, 2020, 12:56:25 AM »
There's a thin layer of brown residue covering most everything that touched fuel in the carb bowl.  Simply soaking the brass bits in lacquer thinner doesn't do much; I can scrub it off with a cab-cleaner-spray soaked rag.  But the stuff doesn't scrub off the plastic floats; I can, however, scratch at it with my fingernail!

[ Guests cannot view attachments ]

I didn't soak the floats, which I think might help - can I safely soak them in the lacquer thinner or carb cleaner, without fear of melting them?

Offline taysidedragon

  • SOHC Master
  • Posts: 1318
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #317 on: April 15, 2020, 11:22:19 AM »
I only used carb cleaner and wd40 on mine. I was afraid to use anything stronger in case of damage.
Gareth

1977 CB400F
1965 T100SS

Offline mattsz

  • SOHC Pro
  • Posts: 606
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #318 on: April 21, 2020, 04:59:33 PM »
I only used carb cleaner and wd40 on mine. I was afraid to use anything stronger in case of damage.

Thanks...

Offline mattsz

  • SOHC Pro
  • Posts: 606
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #319 on: April 21, 2020, 05:03:16 PM »
More minor progress... I went to change the front tire, and found a few rusty spots inside the rim.  I thought I'd scrub off the rust and maybe spot prime them?

[ Guests cannot view attachments ]

Offline taysidedragon

  • SOHC Master
  • Posts: 1318
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #320 on: April 21, 2020, 05:11:25 PM »
That rim looks pretty good. Much, much better than what I found on mine when I took the tyres off. ☹
Gareth

1977 CB400F
1965 T100SS

Offline mattsz

  • SOHC Pro
  • Posts: 606
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #321 on: April 21, 2020, 05:43:29 PM »
That rim looks pretty good. Much, much better than what I found on mine when I took the tyres off. ☹

Small victories, then! 

Here's a photo of a rim off my bought-brand-new Royal Enfield, taken when the bike was only a year old with only 2000 miles on the clock:

[ Guests cannot view attachments ]


Does my touch up and spot prime idea sound like a suitable one?

Offline taysidedragon

  • SOHC Master
  • Posts: 1318
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #322 on: April 21, 2020, 06:18:38 PM »
That rim looks pretty good. Much, much better than what I found on mine when I took the tyres off. ☹

Small victories, then! 

Here's a photo of a rim off my bought-brand-new Royal Enfield, taken when the bike was only a year old with only 2000 miles on the clock:

(Attachment Link)


Does my touch up and spot prime idea sound like a suitable one?

I don't see why not.  👍
Gareth

1977 CB400F
1965 T100SS

Offline mattsz

  • SOHC Pro
  • Posts: 606
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #323 on: April 21, 2020, 06:58:16 PM »

Offline mattsz

  • SOHC Pro
  • Posts: 606
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #324 on: April 27, 2020, 07:31:52 PM »
I''ve turned my attention to the rear wheel - I removed it, and find that when I turn the bearings (and the spacer between them) there's kind of a "crunchy" feel - I'd say the bearings need to be replaced, if they can't be cleaned and re-greased.

I struggled to remove the sprocket circlip, but got it in the end.  Everything is pretty rusty, but it's more like light surface rust, or even a rust-colored fine dust.  Two of the sprocket bolts freely separate from the damper bushes, two are very stuck.  I tried placing a spacer over them and using the sprocket nut to draw the bolt out, but the dampers just stretch and the bolt doesn't budge.  So I've put some penetrating oil to them and am letting them rest for now.


[ Guests cannot view attachments ]


I'm thinking I should clean up the mess - any advice about how to deal with the sprocket bolts?  Can I try to twist them out using the flats that seat in the sprockets?  Or does that put the rubber bushings in jeopardy?  Should I just leave them alone?


I'm working on the wheels because I know the bike needs new tires and chain - and probably sprockets, and probably rear wheel bearings (if not front as well).  These are things I can bring to work with me to work on in spare moments.  But I still don't know how well, or even if, the engine works, so I wonder if I'm putting the cart before the horse?  I'll change the tires because I can, and I have them ready, but I'm thinking I'll hold off on the chain, sprockets and wheel bearings until I know the engine is usable.  On the other hand, the rear wheel obviously needs attention, and it's something I can do now, whereas I can't work on the engine during my work weeks. 

Offline Bryanj

  • Grogu
  • *
  • Posts: 10692
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #325 on: April 27, 2020, 07:38:27 PM »
By the time you have the bearings out, and the way you have to get them out does them no favours either, you may as well buy generic and replace them

Offline mattsz

  • SOHC Pro
  • Posts: 606
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #326 on: April 27, 2020, 07:41:44 PM »
By the time you have the bearings out, and the way you have to get them out does them no favours either, you may as well buy generic and replace them

Thanks!  I figured they were a consumable item - but I've had a couple of bikes with some bearings that had a cleaning and regreasing maintenance schedule.  Not wheel bearings, though...

What do you think about the stuck sprocket bolts, Bryanj - leave them for now, or try to force them out?

Offline Bryanj

  • Grogu
  • *
  • Posts: 10692
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #327 on: April 27, 2020, 08:43:30 PM »
Never had that problem, but also havent done many 400 since i left trade 40 yrs ago!
Unless Julie knows different i would be tempted to leave them alone unless they absolutely have to come out

Offline mattsz

  • SOHC Pro
  • Posts: 606
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #328 on: May 24, 2020, 11:01:36 PM »
I'm cleaning things up - there's a thick coating of chain lube all over everything on the left side, so I decided to remove the swing arm for better access.  It came out easily, but took a long time to clean up using just mineral-spirits soaked rags!

Should the "pivot tube" (which the big bolt goes through) rotate in the swing arm?  I see the grease fitting - what's inside there?  If I start adding grease, will it come out the sides around that tube?

Offline mattsz

  • SOHC Pro
  • Posts: 606
    • View Profile
Re: New (to me!) '77 CB400F - US model
« Reply #329 on: May 24, 2020, 11:09:08 PM »
Speaking of removing the swing arm...

I discovered another bodge when I was removing the shocks - the upper mountings for each one are different, and neither has even close to the correct hardware.  I think the left shock may be done for, it looks like oil has been leaking out:

[ Guests cannot view attachments ]


The right side has a bizarre collection of hardware - a thin brass washer, a too-big threaded nut (looks like the type that secures an electrical switch in a panel) serving as a spacer, a knurled threaded "nut" (looks like something removed from a table lamp's electrical fixings) also serving as a spacer, then - finally! - an acorn nut:

[ Guests cannot view attachments ]

[ Guests cannot view attachments ]


The left side frame mount doesn't even have a threaded stud - there's a threaded hole where the stud should be.  A bolt and two spacer washers secure the shock.  I wonder if it broke and someone drilled and tapped for the bolt, the thread isn't the same as the stud on the right side:

[ Guests cannot view attachments ]

[ Guests cannot view attachments ]


Any reason to be concerned about this for the time being?

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal