Author Topic: 400 Four strip down.  (Read 555 times)

Offline GregShiv

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Re: 400 Four strip down.
« Reply #15 on: December 06, 2017, 10:38:12 PM »
That barrel has a few broken fins that will need repair. Sure sign that the heads been screwdriver prised off at some point.

I think I have counted 3 fins that are broken.

What is the best way to get them repaired, TIG build up?
1983 Suzuki GSX550ESD
2013 Aprilia SL750 Shiver
1976 Honda CB400F

Offline GregShiv

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Re: 400 Four strip down.
« Reply #16 on: December 06, 2017, 10:42:32 PM »
As Julie has posted,  those cam main journals look to be showing wear characteristics.

In addition,  they show a pattern of wear symptomatic of metal embedded into the softer aluminium head bearings. If you can feel any "spikes " in the head bearings by running your fingernail round them,  then that would indicate that they'd need to be corrected somehow before reassembly.
It's something you'd associate with the oil filter pressure release valve being operated so that contaminated oil is passed round the engine.

If that's the case,  you may see the same type of marks when you get to the crank bearings also as they get the oil first.

There is a spike in one of the head bearings, apparently the bottom end was rebuilt 20 years ago and had a new primary chain fitted.
But it looks like the cam chain tensioner has been fitted to the wrong hole, I wonder what sort of damage that could potentially have caused?
« Last Edit: December 06, 2017, 10:59:38 PM by GregShiv »
1983 Suzuki GSX550ESD
2013 Aprilia SL750 Shiver
1976 Honda CB400F

Offline GregShiv

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Re: 400 Four strip down.
« Reply #17 on: December 06, 2017, 10:47:37 PM »
Update on engine strip.
I have taken the head off but the block is reluctant to even move, wooden mallet did not help.
Any suggestion as to the best way to get the block off without further damage to the aluminium?

« Last Edit: December 06, 2017, 11:02:16 PM by GregShiv »
1983 Suzuki GSX550ESD
2013 Aprilia SL750 Shiver
1976 Honda CB400F

Offline GregShiv

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Re: 400 Four strip down.
« Reply #18 on: December 06, 2017, 10:53:29 PM »
More pictures.
Why does one of the pistons have a 4 moulded into the top?
The pistons don't look too bad and the condition of the valves from my untrained eye look ok.
Initial look at the bores seem ok.
What are the opinion of the group?
« Last Edit: December 06, 2017, 11:02:25 PM by GregShiv »
1983 Suzuki GSX550ESD
2013 Aprilia SL750 Shiver
1976 Honda CB400F

Offline GregShiv

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Re: 400 Four strip down.
« Reply #19 on: December 06, 2017, 10:57:03 PM »
The frame and all black metal bits are at the powder coaters, the frame is just going to get "shot" blasted so that I can get the rust holes on the frame assessed and repaired.
1983 Suzuki GSX550ESD
2013 Aprilia SL750 Shiver
1976 Honda CB400F

Offline K2-K6

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Re: 400 Four strip down.
« Reply #20 on: December 07, 2017, 09:01:43 AM »
As you say,  generally from those pictures the bores don't look bad as the hone marks are still clearly visible. A better view of them would be wise after they are removed.

Cylinder head, initially leave valve in and with it upside down on a bench,  fill each combustion chamber with something like thinners (or vodka  :) )  and leave to see if it seeps out past the valves and runs out the ports. It'll tell you if they are sealing or not as initial inspection.

Replacing fins,  use duralumin sheet cut to rough shape and tig tac to barrels,  then complete weld followed by coarse emery or file to shape.

Clutch cover,  if it was welded with any contaminants like oil in material it can be porous so refinishing it could expose some holes. But worth trying to reshape the outside,  use emery cloth and plenty of paraffin to get good finish. If it's too much of a problem it may be worth sourcing another if you cannot get at decent cost.

Getting barrels off,  someone else on here went through recently (maybe worth search for post)  but I'd start by putting penetrating oil down the stud holes that are the external ones. They can be really stuck by the base gasket and maybe worth tapping at centre front and rear with softwood drift to get the gasket to release. Don't prise the fins though.
Added to clarify,  try to tap barrels back and forth not upwards,  aim to get the base gasket to release before you go any further.
« Last Edit: December 07, 2017, 09:38:25 AM by K2-K6 »

Offline Nurse Julie

  • 1973 CB750 K2.1977 CB550/4 Project.1978 CB400/4.
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Re: 400 Four strip down.
« Reply #21 on: December 07, 2017, 09:42:55 AM »
Update on engine strip.
I have taken the head off but the block is reluctant to even move, wooden mallet did not help.
Any suggestion as to the best way to get the block off without further damage to the aluminium?

I had difficulty getting mine apart. After checking again that all the bolts had been removed it was a case of persevering with the mallet and eventually it started lifting. As mine had the original factory fitted gasket in situ, it was well stuck together. Don't attempt to prize up by the fins, it will end in more tears  :'( :'(
« Last Edit: December 07, 2017, 03:26:12 PM by Nurse Julie »
Im a Nurse, trust me, this won't hurt.....much !!!

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

Offline taysidedragon

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Re: 400 Four strip down.
« Reply #22 on: December 07, 2017, 09:40:24 PM »
The clutch cover repair is pretty ugly. If you grind it down smooth you might open up a hole or crack underneath and need another weld to repair. What's the inside of the cover like?

The picture of the other side of the cover is included.
Look just as bad but there looks to be plenty of metal on both side to get an improvement?

I noticed that later. That's the problem when you view it in a hurry! 😕

Good luck with the grinding and polishing. ☺
2010 Street TripleR
1977 CB400F

Offline GregShiv

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Re: 400 Four strip down.
« Reply #23 on: December 08, 2017, 12:24:09 AM »
Thanks for the reply's guys.

I have put plenty of penetrating oil down all the stud holes and will give it another try over the weekend.

I will then give everything a good clean so I can examine it all properly and will post a few pictures.

I am planning on getting all the alloy parts aqua blasted at some point.
1983 Suzuki GSX550ESD
2013 Aprilia SL750 Shiver
1976 Honda CB400F