400 Four strip down.

[GregShiv]

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.

[hairygit]

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.

[GregShiv]

Yes I noticed that as well, I will be giving it a cleanup and have a proper look.

Thanks.

[Trigger]

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.

[Integra99]

 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.





My new ss studs....

[ogri211]

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.

[GregShiv]

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.

[GregShiv]

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.

[GregShiv]

I also found repaired damage to the clutch cover, a bit of aggressive polishing might see this improve?

[Nurse Julie]

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.

[taysidedragon]

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?

[Bryanj]

Seen way worse heads used and run ok

[royhall]

That barrel has a few broken fins that will need repair. Sure sign that the heads been screwdriver prised off at some point.

[K2-K6]

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.

[GregShiv]

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?