Urgh what a mess - CB400N rebuild

[grahamd1]

I wish I could share a before pic, but to be honest if I did I dont think anyone who follow this thread, URGH is not a strong enough thought.
Some pratt has sprayed the engine RED, and done such a shit job (read on), it beggers belief. But its an ill wind that blows no good, and due to the RED engine, the seller couldnt sell it (Fleabay), so he took to breaking it, unfortunetly before I got to it, the tank, brake calipers, master cylinder, coils and few other bits had already been sold, but I got the rest for a reasonable amount for a 400cc 1981 bike. The bonus was being part stripped it went in the back of the old picasso no bother.

Just look at this for a fuse?

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1261.jpg

Here we go one shitty looking red engine, also the eagle eyed will notice one stud missing, one stud over size, one stud welded, so where off to a good start, no ?

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1275.jpg

Still its only paint ?

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1278.jpg

Took a copy of the haynes manual page on the sequence of bolt removal for reference, and got on with it

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1280.jpg

Once the bolts and rocker carriers were out I put them on top of the sheet, so should make putting them back easier.

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1282.jpg

Just look at the plug, WTF

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1284.jpg

Then found the paint was acting like a thick glue and neither the head or the barrel would come off, so had to apply lots of paint stripper and wait. After a while the paint stripper seams to be doing its job, all be it slowly, but I did manage to get the head off

Turned it over to look at the valves, and that damn paint has got everywhere

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1285.jpg

OK, it will get a decoke, and a regrind of the valves, then I looked at the pistons, and could NOT believe what I saw, I reckone someone has dropped this split washer into the plug hole, either a joke or something nasty (wonder if it was the seller ?), no evidence of damage in the head, so it couldnt have been in there the last time it was run. But SURE glad I stripped her down.

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1287.jpg

Time to try removing the barrell, still stuck fast, ok got no choice time to get the tyre levers out, and gently pry around the base in the four parts that are braced, and slowly...... (or as a very old tv advert used to say, in a poor French accent "Gwaduulie") the thing started to move...... (or in war of the worlds, "suddenly the lid fell off".

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1289.jpg

Quck get some wire in place to stop the cam chain doing a runner (like toilet paper)....(bin there done that)

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1290.jpg

Look, there be pistons in here

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1292.jpg

Looks like she has been loosing compression and oil from one cylinder, however the barrels look very nice, no scoring or strange marks or excessive wear, but I gather thats the norm for the superdream engines?

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1294.jpg

If I get time, I will take the barrel over to my mates car garage and hone them out (car mechanics call it "busting the glaze"), and then do some measuring.

Finally two pistons removed

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1296.jpg

Time for the scotchbrite me thinks, then I should be able to find the piston sizes so I can get some shiney new rings.

At this point, should I stop, hmmmm not sure, part of me says split the case, other part says leave alone.....
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[swanny]

Lordy me you have a job on there !!

Its like someones just gone hell for with the spray, coating the spark plugs and cam adjuster is just foolish..

good luck and keep adding more pics, be cool to see how it turns out.
____________________
M SWANNY.. see a sig !

[N cee thirty]

seems all older bikers are fucked from retards so don't except anything to be right
____________________
'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[grahamd1]

[Eddie Hitler]

Saw that advertised and certainly thought "wtf" myself. Good luck

[grahamd1]

[et1]

Yep you were right. That red pain looks horrible.

[stevo as b4]

It's nice to see a superdream project, and I've never seen the internals of one of these engines before, so it's interesting. What did Honda claim for the 400's power wise? I seem to remember 43bhp being quoted, which is plenty from an air cooled 400cc twin!

[waffles]

I love the way that they just painted the engine. ALL of the engine including the spark plugs and valves. Well classy!
____________________
Theory test - 19/8/09, CBT - 11/10/09, MOD 1 - 16/8/10, MOD 2 - 27/10/10
Past rides Yamaha XT125X, Triumph TT600, Honda XR250
Current rides Suzuki GSXR 600, Honda MSX125

[dangerousdave]

a lot of work you've got there !

my dad had the CB250 Superdream which was on the heavy side & a bit underpowered. the 400 is same weight but more powerful so should make a good bike once done.
____________________
1988 Kawasaki KMX 200

Previous: Yamaha YZF1000, ZZR600, KMX200, DT50, KX80, CG125, PF50

[grahamd1]

A quick update and real kick in the teeth

Took the pistons out, measured them for new rings, BOLLOCKS its a 250 engine, NOT a 400, someone has layed sealant and paint over the serial number of the engine, but its just about visable now I have wirebrushed it, CB250N. I've raised a claim against the seller with PayPal, clearly NOT what was sold.

Meanwhile ANYONE got or know of a 400 for sale?
____________________
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CD175 (Rebuild)
CF70 (Chaly - Rebuild),

[MarkJ]

That's a shitter

Was it the last guy who painted it & covered up the serial? Does the V5 say it's a 400?

[stevo as b4]

How did they get 400cc though?
Was it a big bore 250? Stroked? or both?

I'm just wondering if like an LC250 you can easily convert to a 400cc top end assuming you had/could find the bits?

[grahamd1]

V5 says 400cc, and frame number confirms 400, so who knows who or why it had a 250 in, the serial number of the red engine (that you can read), begins CB250N so its a genuine (BUT RED) 250cc engine in a 400cc bike, not the normal way of doing it, is it.

Apart from fleabay, and gumtree and an add in the wanted on here, I'm not sure where else to find one
____________________
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CD175 (Rebuild)
CF70 (Chaly - Rebuild),

[Kickstart]

Hi

250 engines were cheap and 400 engines kept their value. Hence they blow an engine and just wanting cheap transport the 250 would get it back on the road for min money.

Years ago I had a CB400NC. Handled OK. Comfy enough. Speedo seemed to under read though (most I ever got was 96mph, except I was clocked at 105mph at the same time).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Blau Zedong]

[jameswood]

looking good!

actually its looking shit but looks like it will look good!

[grahamd1]

Someone must have come off at some point, this is the handle bar holder (again hidden by layers of paint)

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1303.jpg

Found one on fleabay for a fiver.

Started stripping and cleaning the handle bar switches (yep spiders be in here)

https://i314.photobucket.com/albums/ll431/grahamdrry/IMAG1310.jpg

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1318.jpg

When I got the bike the tank was missing (part of the cheap deal), but I ordered this one from fleabay.fr (yep France) on Sunday evening, for £38 inc delivery, guess what arrived today !!!!

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1316.jpg

Ignore the colour, its going to be stripped and painted, but came with key/lock and tap, outstanding price (they go for £70+ here)

Finished stripping the frame, now thats in great shape (shame about the swingarm, but I have one on order).

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1317.jpg
____________________
XV1100, XV750
CD175 (Rebuild)
CF70 (Chaly - Rebuild),

[grahamd1]

Also now have an engine, just got to work out how to get it from N-Yorks down to Bedfordshire (pic is before it was removed)

https://i.ebayimg.com/t/Honda-Superdream-Cb400-Engine-/00/s/NzUwWDk5OQ==/$(KGrHqN,!q8FBIgMGQgJBQnBpE7Yng~~60_12.JPG

I tried shippley a few days ago, hedging my bets, and only got 1 quote £58.
____________________
XV1100, XV750
CD175 (Rebuild)
CF70 (Chaly - Rebuild),

[janner_10]

Really interesting thread, keep us informed
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Yamaha FZS600 (Now gone to heaven) > CBR600F4i (SOLD) > '99 YZF-R1

[Hobgoblin]

[Rowey]

Nice project. I had a 250N a while ago. They're lovely bikes to work on. Very well made and finished too. Mine was abandoned in a garage for ten years, apart from some furring on the ally she was solid. After a new battery and fresh fluids she started first time.

I spent about 4 months rebuilding it as a rolling restoration.

Unfortunately a week after I had stripped and repainted the frame, engine, wheels and side panels. I was popping to the bike shop to pick up some provisions when a blind sod in a rush to pick up his kids pulled out on me and squashed it into the curb.

The forks and stem folded from the impact and it was written off... Poor thing.

Anyway, keep up the good work!
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ZX6R C6F.
Never argue with an idiot. They'll only bring you down to their level, and beat you with experience.

[stevo as b4]

I regulary see a blue CB250N riding into Birmingham from Halesowen, and another black one parked in the city near St Phillips cathederal.

I didn't realise how rare the 400's had become in comparison though! I wonder if it's the same for the XS250/400's and Z250/400/440's, as i've not seen any of the above for years!

I must admit that i do quite like the Honda CB350S though, it was once described as what a Harris framed superdream would be like!

[Tbag]

[grahamd1]

Stripped down the speedo assembly as it was scratched and very faded

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1323.jpg

And a rub and a squirt of black bumper spray

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1325.jpg

Must have spent most of yesterday (well it was too damp to spray), rubbing the frame down. Then finally this morning the weather gods shined, and the sun came out and the temperature rose.

Always love it when that first coat goes on perfect, first time (it dont happen often).

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1326.jpg

Now on with the second (1st has been on for a few hours).
(The hanging basket is perfect for holding frames etc)

https://i314.photobucket.com/albums/ll431/grahamdrry/CB400N/IMAG1327.jpg

Ahh happines is a frame almost ready to go back together....
____________________
XV1100, XV750
CD175 (Rebuild)
CF70 (Chaly - Rebuild),