SOHC.co.uk Forums > CB350/400

Engine Strip - I'm nervous

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waffey:
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?
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waffey:
and some more pictures

Trigger:
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. 

waffey:
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.

Nurse Julie:
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.

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