Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: GregShiv on November 19, 2017, 07:42:00 PM
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Hi,
I am in the process of stripping down my newly bought eBay 400 Four.
It is now in bits and I will soon be getting the frame, swing arm and various bracketry blasted and powder coated.
One exhaust stud is refusing to come out and one of the fork "pipe compression seat" bolts is refusing to budge even with a cordless impact driver.
The engine is a runner after I got power to the coils but will be getting a strip down and examination in due course.
Loom had been hacked, every connector had been cut off and the looms soldered and wrapped in insulation tape. So new loom ordered along with a lot of other missing or damaged parts.
The question I have is that there is a rust hole on the back of the frame and I would like to know what would be the best thing to get done to it i.e. welding?
Any advice greatly appreciated.
Picture attached.
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Enlarging the picture of the hole in the frame, it looks like it is cracked around the top part as well. May just be a scratch in the grime, but it certainly warrants close inspection when cleaned up, as any cracking in that area is serious, it's what takes the load/shock from the rear suspension unit, any weakness here can spell disaster if not dealt with properly.
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Yes I noticed that as well, I will be giving it a cleanup and have a proper look.
Thanks.
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Take it too the blasters (beware some blasters are animals and over do it, leaving the frame looking like a tea bag) once cleaned then you can truly assess the frame. Also have all black painted metal parts blasted.
1, FRAME
2, SWINGING ARM
3, TOP & BOTTOM YOKE
4, FOOT PEGS
5, REAR LIGHT BRACKET
6, BATTERY BOX
7, ELECTRICS PLATE
8, CLOCK BRACKET
9, TORSTION BAR
10, SEAT PAN
11, ENGINE MOUNTING PLATES
12, And anything else in hard metal you want painted.
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Good luck with the rebuild, I'm slowly rebuilding my CB400/4 had the same issues, in the end.. the exhaust stud came out with penetrating oil and lots of heat and very very small movements... it often helps trying to tighten the bolt as well.
I had the same hole in the frame, had it welded and the frame sprayed rather than powder coated.
(http://www.sohc.co.uk/gallery/14623_22_09_17_8_41_14.jpeg)
(http://www.sohc.co.uk/gallery/14623_22_09_17_8_42_21.jpeg)
My new ss studs.... :)
(http://www.dotheton.com/gallery/107242-301017035113.jpeg)
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That hole in the frame looks as it comes from water sitting in between the plastic mudguard and frame mine was rusty at the same bit on the left hand side it will be caused by the bike sitting on the side stand thats why most of the rust is on the left side.
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Progress so far.
Cleaned up the frame and it was a scratch in the dirt. The rust hole looks like it was caused by water build up as the side that has rusted has a space at the top that has allowed water to get in and not drain out.
I will be getting every black painted metal bit powder coated, all the bits are in a crate waiting to get done.
The bike has tapered roller bearings fitted to the yokes but they look pitted so will replace them.
Have been stripping the engine down and I have a few concerns around the cam and bearing journals in the head and rocker cover.
There was plenty of clean oil in the engine and no signs of anything suspicious in the filter or strainer except for a missing spring and the rubber seal around the strainer having perished.
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A few more pictures, I did find a lot of blue gasket material hanging off inside the head area. But there was loads of oil so it does not appear to have been caused by oil starvation.
Do you think it is serviceable?
The cam journals feel smooth but I don't think the head surface looks too good with the scoring.
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I also found repaired damage to the clutch cover, a bit of aggressive polishing might see this improve?
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Some of the cam journals do look a little iffy. Will be able to see more when all the old dirty oil has been cleaned off I expect.
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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?
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Seen way worse heads used and run ok
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That barrel has a few broken fins that will need repair. Sure sign that the heads been screwdriver prised off at some point.
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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.
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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?
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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?
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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?
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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?
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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?
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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.
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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.
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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 :'( :'(
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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. ☺
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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.
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Update.
The frame has been welded and realigned at Maidstone Motorliner. Headstock, exhaust hanger and rear frame rails were all out of alignment.
Where the metal had rusted at the rear left shock mount it had also rusted at the frame rail this was all welded/brazed and made good.
frame has now been powder coated along with all the other black parts but I am still waiting to get the top yoke back as the powder coat had bubbles showing.
Still waiting to get the engine casing back from the vapour blasters!
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More frame pictures.
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The frame as it is now, and yes it is in the house. I have a very tolerant wife ;D
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Looking good Greg. All bikes should be in the house !!! ;D ;D ;D ;D ;D
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Here are some pictures of the bike as it was picked up when I bought it late last year.
No indicators or mounts, non standard seat, none standard rear mudguard, loom bodged up etc
[attachimg=1][attachimg=2][attachimg=3]
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I agree Nurse Julie :)
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A few pictures of the engine, Primary chain is worn, so new primary chain, cam chain, oil seals etc will be fitted the main bearing all look fine no scoring or wear marks.
Will need a rebore though as there are a few scores and water/rust marks.
One of the barrels had no o ring but whoever rebuilt the engine 20 years ago used blue sealant instead of replacing the o ring.
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A repair had been done by PO, not good looking.
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Don’t know why the photos aren’t orientated correctly but come out correctly when they are clicked on?
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