Author Topic: Engine Strip - I'm nervous  (Read 1275 times)

Offline waffey

  • SOHC Associate
  • Posts: 89
    • View Profile
Engine Strip - I'm nervous
« on: January 03, 2020, 02:46:52 PM »
Hi All,

so i'm finally getting on with the Honda CB400 1977. I've asked many questions on here so far with plenty more to come.

I'll try and bring you all up to speed.

(1) ]Bike has been stripped down an now lives in boxes.

(2) I've started to refurbish the clocks but awaiting to make a decision on the clock faces, that is either to get vinyl over layor leave them as is. I'll probably go with 'leave as is'

(3) The frame is due to go to the powder coaters next week along with the yokes and some other bits as recommend in a previous post.

(4) I'm stripping the engine at the moment (Yet to split the crankcases). This is where I'm going to struggle. I've noticed the following things
(4a) Some of the fins on the oil filter are damaged.
(4b) The sump pan has been welded around the sump plug.
(4c) The oil pick up filter has metal pieces in it. It was also covered in thick gunge almost like gearbox oil.
(4d) The pistons and head are covered in thick carbon.
(4e) Removing the barrel some of the piston rings fell out (they were in two pieces).
(4f) The cam tensioner adjuster has been broken.
(4g) The barrels look ok but I need to measure them yet.
(4h) The pistons look ok but I need to measure them.

So my current  plan once I've split the crankcases are: Check crank bearing shells (plastic gauge them), measure barrel and pistons firstly for wear and to understand if the engine has standard pistons. Then get all the cases cleaned and checked. Then my plan is to get the barrels honed / rebored if required with new pistons ect, new bearings etc and then start to rebuild the engine. I want the engine in  the frame as I think this will be the easiest way to build the bike back up.

Please feel free to comment and give me guidance.

Is there anyone nearby to Plymouth that maybe able to help me / guide me?
[ Guests cannot view attachments ]

Bikes:
Suzuki Address 110 Scooter
Suzuki TL1000s
BMW R1200GS LC
Honda CB400 F2 1977 (restoration started)

Offline waffey

  • SOHC Associate
  • Posts: 89
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #1 on: January 03, 2020, 02:54:36 PM »
and some more pictures
Bikes:
Suzuki Address 110 Scooter
Suzuki TL1000s
BMW R1200GS LC
Honda CB400 F2 1977 (restoration started)

Offline Trigger

  • SOHC Jedi
  • Posts: 6891
  • Engines built on reputation, not advertising.
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #2 on: January 03, 2020, 03:18:09 PM »
Clocks send to Peter or put new faces on.

Focus on the bottom end as, that is the first part you want in the frame. If a ring or two has broken then there should be marks in the bores. 0.50 piston kits are cheap and get them rebored and matched by someone that knows Japanese engines.

The bottom end needs a close inspection and replace cam chain, primary chain, primary rubbers and seal kit as STD if the engine is high mileage, you don't want to be going in there again. 

Offline waffey

  • SOHC Associate
  • Posts: 89
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #3 on: January 03, 2020, 04:33:30 PM »
Thanks trigger.

No score marks on barrels but the engine sat for a long time unused (plus 15 years). I think its 48,000 miles on the clock.

Do I really need to replace the primary chain as a matter of course?

There is a local machine shop nearby which I will approach for the rebore.
Bikes:
Suzuki Address 110 Scooter
Suzuki TL1000s
BMW R1200GS LC
Honda CB400 F2 1977 (restoration started)

Offline Nurse Julie

  • 1973 CB750 UK K2.1977 CB550/4 Mongrel Brat. 1978 CB400/4.
  • SOHC Jedi
  • Posts: 5059
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #4 on: January 03, 2020, 04:38:14 PM »
Fully investigate where the metal debris has come from in the sump / oil strainer. Is it the broken rings, or mushed up gearbox components etc. If metal debris has been going around the engine, all bearing surfaces / cam shaft / bores etc may have sustained major damage and maybe beyond repair. Good luck with everything and replace the cam chain and guides and hyvo primary etc. At 48k, they will be on their last legs, if not beyond.
« Last Edit: January 03, 2020, 04:40:47 PM by Nurse Julie »
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Online Bryanj

  • SOHC Jedi
  • Posts: 6108
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #5 on: January 03, 2020, 05:55:12 PM »
Yes it is necessary to replace primary chain and cush rubbers

Offline PatM

  • SOHC Member
  • Posts: 195
  • 2001 R1, Triumph 1200 and the little 400/4!
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #6 on: January 03, 2020, 05:57:25 PM »
Trigger and Julie know their stuff as they have done all this before.
Just to pick up on one of your points which I think i can answer-

(4c) The oil pick up filter has metal pieces in it. It was also covered in thick gunge almost like gearbox oil.

When I rebuilt mine 9 years ago . I bought it as a sorry-state non-runner. Id not had one since the early 90's.
I popped off the sump and found the same as you-it was aluminium gunk and bits all over the strainer, so I cleared it off and promptly put it all back together without to much consideration as to where it has come from. I was hoping it was general wear and or sloppy oil-changes.

I was chatting on here to Julie about cam-chain adjustment as I went to 'adjust' mine and undoing the adjuster made little difference-even though its a stainless steel bolt and nut. The penny dropped-my lower cam-chain horse-shoe has seized.
 Now, Julie told me Id have to strip the motor to replace it-which is correct-but I read about this somewhere and although its not a permanent fix (Julie said its a bodge..) You can insert a long thin drift down the throat of the chamber-accessed via the large cap thats above the adjuster- and 'tap' the drift. This, in my case moved the lower horse-shoe and shut the cam-chain up. The metal on the strainer was non-metallic and caused by the chain rubbing/eroding the throat of the chamber.
Im actually and engineer!-but I saw little benefit at the time stripping the whole motor-I retire in a few years, have too many other bikes to maintain and cars...Ill save all that for then-its not as if the 400/4 gets much use-used in thrice in 2019- and I know what the cam-chain sounds like when its loose!
I also plan to do the head/valves but if Im going to remove the motor and start dismantling it-Ill do it once!
Ive rebuilt these motors before back in the early 80's and I know how easy bolts strip or heads snap off- my bikes running perfectly well and Im not into causing myself a load of grief, neither have I the spare cash to instantly resolve it! Back in the 80's you can pick up a running 400 motor for £50- no problem- the breakers were full of them in London area.


Offline waffey

  • SOHC Associate
  • Posts: 89
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #7 on: January 03, 2020, 10:21:16 PM »
Thanks PatM,

i'm hoping my 'bits' in the strainer are the same as yours. Hopefully i'll have the crank case split this weekend.

I'll post some more pictures then. The frame is booked in for the 10
Bikes:
Suzuki Address 110 Scooter
Suzuki TL1000s
BMW R1200GS LC
Honda CB400 F2 1977 (restoration started)

Online Bryanj

  • SOHC Jedi
  • Posts: 6108
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #8 on: January 03, 2020, 11:09:32 PM »
Considering you had broken rings i would not even bother measuring but buy oversize and rebore, chances are that the broken rings have worn the ring grooves in the pistons.

Offline Trigger

  • SOHC Jedi
  • Posts: 6891
  • Engines built on reputation, not advertising.
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #9 on: January 04, 2020, 09:07:24 AM »
As Bryan has already said, not worth the trouble with the pistons , a engineering shop can charge around £45 just to measure up and then tell you that you then need a rebore. You can get a good oversize set from Japan for about £110 including post. Get a good engineer to rebore at a piston to bore clearance of one thou , if anyone tells you that this is too tight, walk away as, they don't know what they are doing.

If the sump pan is leaking from the drain bolt, look for a good secondhand one that has not been welded. Never torque a sump bolt more than 20 ftlb on these old girls or they will crack the pan  ;)

Offline waffey

  • SOHC Associate
  • Posts: 89
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #10 on: January 04, 2020, 10:23:46 AM »
thanks trigger. advice taken. hopefully, strip the crank case today then i'll post some more pictures

something like this as a piston set? https://www.ebay.co.uk/itm/264088297262
« Last Edit: January 04, 2020, 10:26:32 AM by waffey »
Bikes:
Suzuki Address 110 Scooter
Suzuki TL1000s
BMW R1200GS LC
Honda CB400 F2 1977 (restoration started)

Offline Trigger

  • SOHC Jedi
  • Posts: 6891
  • Engines built on reputation, not advertising.
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #11 on: January 04, 2020, 10:33:26 AM »
Yep, that piston set will do  ;)
Just remember to mark the shells as to were they come from, if mixed then you will need a whole new set.

Offline Oggie400F

  • SOHC Associate
  • Posts: 82
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #12 on: January 04, 2020, 01:54:54 PM »
As Bryan has already said, not worth the trouble with the pistons , a engineering shop can charge around £45 just to measure up and then tell you that you then need a rebore. You can get a good oversize set from Japan for about £110 including post. Get a good engineer to rebore at a piston to bore clearance of one thou , if anyone tells you that this is too tight, walk away as, they don't know what they are doing.

If the sump pan is leaking from the drain bolt, look for a good secondhand one that has not been welded. Never torque a sump bolt more than 20 ftlb on these old girls or they will crack the pan  ;)

Hi Trigger
Are the piston sets from Japan via Cruzinimage or someone else?
I'm a Radiographer............I can see right through you!!

1999 VFR800 fix in Pearl Prism Black
1978 CB750F1 in Candy Presto Red
1976 CB550F Supersport Brat Bike in Black
1976 CB400F in Varnish Blue - project bike in many bits.

Offline waffey

  • SOHC Associate
  • Posts: 89
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #13 on: January 04, 2020, 03:57:55 PM »
Hi,

crank case split, I cant find any damaged teeth or casing. must o been a bit of? a piston ring, alloy from the welded sump or who knows!!

Bikes:
Suzuki Address 110 Scooter
Suzuki TL1000s
BMW R1200GS LC
Honda CB400 F2 1977 (restoration started)

Offline waffey

  • SOHC Associate
  • Posts: 89
    • View Profile
Re: Engine Strip - I'm nervous
« Reply #14 on: January 04, 2020, 04:01:00 PM »
and some more pictures

the last one showing a snapped bolt for the cam tensioner and the engine bracket and stud I cant remove. Might have to send to an engineering shop to have these removed.

the cam tensioner itself is seized as expected
Bikes:
Suzuki Address 110 Scooter
Suzuki TL1000s
BMW R1200GS LC
Honda CB400 F2 1977 (restoration started)

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal