Down Under 1975 CB400F Restoration Project

[Andych]

So.. it is time I outlined my what plans I have for my project and added some pics..comments, information and suggestions all welcome

I picked this little gem (in the rough) up from a country town in Northern NSW called Grafton... and after a couple of false starts I had it shipped down to me... it was well worth the $350 so I didnt have to drive 400km each way and with a Hotel bill thrown in.
It arrived a few weeks ago and I resisted immediately tearing it down as I had a Suzuki Across on the bike lift that was meant to be a quick flip (12 months ago) but now that has gone and I have had a chance to ponder a little more about what I want and also to see what condition the bike is in.
I did get myself a new battery and using the well worn Kick starter (more on that later) had it running just a a few minutes which was encouraging... there is an issue in the starter circuit (most likely the button or an earth or both) so with some new fuel in it I used a screw driver across the solenoid connections and turned it over a few times just to get some oil moving... then opened up the petcock, lifted the choke and she fired first kick. When I ran it the first time it blew the remains of about 3 wasp nests out of the exhaust but this time it just settled into a nice idle.
The exhaust is cactus (Aussie slang for dead) so it was tough to listen for too many noises but once it was warmed up a little it revved nicely which I was pretty impressed with. Mainly because the seller had said it will run with a battery and I am always sceptical There were no unusual rattles, it didnt blow any smoke etc.. BONUS
So.. I know it runs which is always a plus... not that it mattered as I was always going to tear it down... all the way so that I can have the cases vapour blasted, Primary and cam chains changed and barrels bored. I was going to go the 466 (54.5mm) route but after reading through here I am now thinking I might just see how much wear is in the bores and decide from there... but I will probably end up going 52.5mm which I think is the largest factory oversize as long as I can get pistons and rings...plus I will tidy up the ports a little. Nothing wild.. just some smoothing and port matching the intakes (so I say at present anyway).

So the project overall is to try and keep the bike as close to stock or looking stock as I can. The Colour will be Varnish Blue.. or maybe a custom blend of Varnish Blue with some Candy in it.. just to make it pop a bit. I want it to look standard but for people to look at it and not be able to put their finger on what is not right...
I definitely need to get another seat as the one on it has the wrong cover and the base is rusty and has been welded a few times before.
As I said before.. the exhaust is just not salvageable, the pipes are all dented and number 2 pipe has a large hole up near the head... the muffler is an orphan so I looked around and I decided I am not going to shell out for Factory headers.. they just want stupid money for really rough ones and the Delkevic 4 into 1 megaphone looks pretty good and I hope sounds lovely. I have heard some Youtube clips of 500's and 750's but no 400's yet.
Front end will remain stock.. maybe change fork springs depending on how they are.. (I am sure they will be stuffed) but the rear end has already been acted upon... the rear shocks at present are SW but they are bulkier at the bottom than factory so the chain guard has been sliced up to suit and when I took the LH one off today I can see the chain has gouged a nice recess in the shock. Luckily I purchased a set of aftermarket twin spring shocks last week and they will miss the chain easily so I just need a new chain guard now.

All the other usual stuff I guess... Instruments refurbished and outer painted with new KPH faces and crimp rings. I already have the tank and side cover decals as well as the idiot light decal and will probably get the warning label decals as well.. just to make it look authentic. Wiring doesnt look too bad right now but I will see as the strip down starts.. Reg/Rec will be changed and will go to blade style fuses... plus at this stage I am leaning towards a Hondaman Electronic ignition.
That is it for now.. a broad outline of what I want to end up with... a clean stock looking keeper...
Plenty of pics below and I will try to keep this as up to date as I can.. but I also have another build on the go at the same time (a Yamaha SRX250) so the CB400 will be a little slow to start with.

This is the first pics I had of it before I bought it
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I took the tank off only to find more wasps nests.. didnt seem to hamper the coil pack operation as it ran fine.

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When chain meets shock absorber

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New shockers ready to go on when the build takes place...

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[Nurse Julie]

That looks a good basis for a restoration Andy, good luck.

[Andych]

Thanks Julie
Overall I think it is a good basis to create a lovely bike... I have plenty of work cut out though..
I need to make myself a new Side Stand mount for the frame... as you can see from the pics below some previously did a poor welding job on a makeshift bracket.
I managed to get a really nice powder coated original side stand and I have what I think is a good template for the bracket.. once I get the frame stripped down this part will be cut off and a new bracket welded on... plus everything cleaned up in that area... so far.. (famous last words) I cant see any other major issues with the frame.
The engine has the typical oil weeps from under the head and lots of cleaning and polishing of alloy.
I need to see about getting my tank repaired as well.. it seems to have been pushed down slightly around the filler cap.. hopefully it wont be too hard to do.

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They didnt get the angle even close to correct.. and you just have to love the welds...lol

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[Andych]

Hmm looks like I will need to keep updating this a little more often..
OK, so what has been done since I last posted.. not a lot but..
I did manage to secure a complete engine with carby stack for A$400 and I have to say I was pleasantly surprised when it arrived.
All the fins and covers look to be in better condition than the original engine (still in the bike) and after having a look down the bores with my $18 borescope (not as hi-res as they say) there doesnt look to be a great deal to worry about.
It had reasonable compression when turned over on the kick starter and I can really only see one cylinder with what looks to be a vertical groove in the bore.. time will tell if it was a good buy or not but spare parts cannot go astray.

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I also got a good deal on a Big Bore kit.. I just couldnt resist.. Under A$300 and it arrived today and the piston I have a look at was quite good.. no sharp edges or casting flash.. all packaged well so we will see when it comes time to bore the barrels. I at least have a spare set that I can take back to more standard size if this lot doesnt work out..

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[paul G]

Keep up the good work Andy following with interest 

[SumpMagnet]

Ummmm...your electrics work better than mine. Wonder if I should fit some aftermarket wasp nests for a better spark!

[Andych]

Surprisingly it ran fine.. started easy once I used the old screwdriver on the starter solenoid.. I think there is an issue with the starter switch.. but that will be looked at in due course

[Andych]

Wow... nearly 12 months on and I have finally started to do something.
I decided that I really want to ride this bike so for now.. it is more about tidying it up and making it roadworthy so I can get out and have some fun on it.
Having said that.. the tank and side covers will definitely be painted.. I cant leave them as they are... that wouldnt be good.

First place to start was to tidy up the battery box and rear area of the frame that seems to have the most surface gunk / rust etc... I eventually found a way to get the battery box out after removing the rear guard, inner guard etc...lol
that will get a quick bead blast tomorrow and maybe some paint and the rear of the frame should get a hit with the wire brush and also get some paint.

I then wanted to see just how bad the exhaust headers are, thinking I might be able to repair them and live with them for a while but.... looking at the pics that might be a step too far.
The leak at the top of Number 2 pipe has been welded before.. but I could slowly do it again with the Mig.. another pin hole in pipe 4 I think and then the crush and grind on number 4 pipe down low where it has been dropped at some stage will be the death knell for this system I think.
The electrics seem to have only been butchered in the Indicators earth lines.. either scotch-loks or twisted and household connectors fitted... easy enough to resolve... I hope

That is enough for now.. hopefully a little will be done each week from now... she will go onto the lift table tomorrow.

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[Andych]

Ok, looks like my plans to get the CB400 back on the road reasonably quickly has been derailed.
While I took the rear sprocket cover off so I could get the starter motor cable off to replace it I had a look at what needed to be done on the frame where a poor welding job on the side stand area. It didn’t look too bad and was able to be done as it sat, UNTIL..........
I felt right underneath and behind and was horrified to find a reasonable part of the frame missing.
Not impossible to repair but it means Engine out, remove the outer patch that is there now and then form up another patch to replace what has been cut out of the frame.
So....if it is engine out then the frame will be blasted and powder coated so certainly not a quick fix.
It is hard to see from the pics as I had to use a mirror but it looks like the Patch they used wasn’t big enough so they just left it open.

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[Andych]

And my parts fro Silvers arrived today as well...not too bad a service for 8 Pounds and British Mail / Australia Post.

[Sprocket]

Holy (holey?) crap that's a big hole!

[Nurse Julie]

Blimey.....NOT an insignificant hole. You may find that when you have the frame blasted, it may resemble a tea bag, ie, lots of holes. Suggest having it blasted first to see what you are working with before doing a fix on that hole.

[Andych]

I am also on the lookout for another frame as well... Maybe my next step will be to grind away the bird droppings that resemble someone trying to weld on the outside so I can figure out what they were trying to do.
The bottom tube seems to be solid forward of the poorly welded on patch and side stand bracket so I am hoping that some of the tube is still intact to enable a repair... at least I can gringd that part off without removing the engine and make my decisions based on what I find.

[Andych]

I have found another frame that has been butchered up for use as a race bike but the bottom rails are good and the best news is it is A$60 so I will pick it up in the next few weeks (it is about 400km away but on my travel route for work).
That should make for a much better repair than just welding a patch on.

[Bryanj]

If that is by the sidestand lug seems to be cropping up regularly on the 400, must be a stress point