CB400N Top end rebuild

[Ant132]

Here are some pics of the top end of my superdream. It didnt seize or break down or anything, im just rebuilding it as i have the week off and the head gasket was leaking and it burns oil .

https://i101.photobucket.com/albums/m62/ant-147/DSC000148.jpg

https://i101.photobucket.com/albums/m62/ant-147/DSC000157.jpg

https://i101.photobucket.com/albums/m62/ant-147/DSC000167.jpg

https://i101.photobucket.com/albums/m62/ant-147/DSC000176.jpg

https://i101.photobucket.com/albums/m62/ant-147/DSC000186.jpg

https://i101.photobucket.com/albums/m62/ant-147/DSC000195.jpg

This being the first 4-stroke ive owned/worked on i havent got a clue if the above pics tell me anything substantial. Am i missing anything obvious or does it all look fine?

My plan is fit a new top-end gasket set and new piston rings all round. What should i be doing with the valves? I was planning on just cleaning everything, getting the excess carbon off and and re-assembling.

Just wondering if im missing anything obvious or any recommendations on what to do or check before i re-assemble?

One thing i noticed is the RH piston is slightly wet with oil whereas the LH piston was dry. Im wondering if this is linked to the fact that when the bike is really warmed up it smokes slightly from the RH exhaust when idling or pulling away.

Cheers for any help, Ant
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1980 Suzuki TS50 ~ 1984 Honda CB400N ~ 1992 Triumph Trident ~ 1998 Suzuki Bandit 1200

[monkeyboy111]

Hi

I got the 250n superdream and does excatly what yours does! i just brought another engine and going to swap it as so cheap!

You are doing a good job i would just replace gaskets pistons and rings, don't really need to replace anything else unless really bad, good old clean will help loads!

Also what else have you done to it? 2 in 1 exhaust? fly screen?

Many Thanks
Carl

[monkeyboy111]

Hi

I got the 250n superdream and does excatly what yours does! i just brought another engine and going to swap it as so cheap!

You are doing a good job i would just replace gaskets pistons and rings, don't really need to replace anything else unless really bad, good old clean will help loads!

Also what else have you done to it? 2 in 1 exhaust? fly screen?

Many Thanks
Carl

[Ant132]

Hi Carl,

Thanks My bike started out as a 250 too. But when i bought it, it had had a 400N engine put in. The problems were there when i had it but they are gettin gradually worse and the oil consuption heavier so now is the time to do it. I did have a look around for a second hand engine but the last 400N engine i saw on ebay went for over £100 and the condition was unknown and im estimating about £70 on parts, labour done my self, so really its cheaper to do repair mine.

It has a replacement exhaust on it but in the standard style, 2 into 2. I recently put a flyscreen on it and would really recommend it if you are thinking of one.

https://i101.photobucket.com/albums/m62/ant-147/DSC000145.jpg

Screen was £20 iirc from getgeared. Just need to find a place that stocks piston rings now, David silver are out of stock so will give them a ring on tuesday and find out when they will be in. Dont suppose you know of anywhere else (none on ebay atm)

Cheers, Ant
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1980 Suzuki TS50 ~ 1984 Honda CB400N ~ 1992 Triumph Trident ~ 1998 Suzuki Bandit 1200

[monkeyboy111]

haha yh my oil is getting worse £20 on oil a week!

yh i have a fly screen aswell very good! i also want a 2into1 exhaust! i changed the colour of mine as plastics were smashed!

Ok for piston rings you need wemoto they are very good! i live just down the road from one so if you want anything i can send it over as they are shit at posting the correct stuff!


https://shop.wemoto.com/index.dyn?flag=17&make=Honda!


Many Thanks
Carl

[Ant132]

Thanks for the link, but they dont seem to stock piston rings either which is unfortunate. Nice 'dream btw, looks tidy

When i bought oil i used to buy a 5 litre bottle from Wilkinsons for £10, it does the job and doesnt make the clutch slip. Still ran great on it. Couldnt stand having to worry about the oil level though and wipe the barrell fins clean after every couple of rides so i have been waiting for an oppurtunity to do it for ages.

Ant
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1980 Suzuki TS50 ~ 1984 Honda CB400N ~ 1992 Triumph Trident ~ 1998 Suzuki Bandit 1200

[monkeyboy111]

What year is your bike or engine? sometimes they dont have it up there?

Haha i got halfords stuff costs £25 its not my gaskets tho i have a crack in my cyclinder head so thats why i have to replace my engine!

Just wondering how fast have you got outta her?

[Ant132]

1984 mate? So they stock seperate to what they have on the website?

Speed wise - I never was too concentrated with the speed of it due to the few problems it had but on the dual carraigeway i took it upto 95 where i backed off. No screen then and it was really windy

After the running in period with the new rings im hoping it should feels loads better
____________________
1980 Suzuki TS50 ~ 1984 Honda CB400N ~ 1992 Triumph Trident ~ 1998 Suzuki Bandit 1200

[monkeyboy111]

Ok i will pop in tuesday for you if you haven't found any by then! i tryed david silver spares once and took 2 months so you could be waiting a long time!

https://cgi.ebay.co.uk/honda-cb400n-engine-superdream-cb400_W0QQitemZ270396001671QQcmdZViewItemQQptZUK_Motorcycle_Parts?hash=item3ef4db8d87&_trksid=p3286.c0.m14&_trkparms=66%3A2%7C65%3A10%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

Really interested in this! when you swapped your engine over what did you have to change? brakes ETC

Carl

[Ant132]

Thanks alot Carl

I didnt change the engine myself, i bought it like that. But from what i have seen all that has been changed is the CDI and carbs. As far as i know everything else remains the 250. Ideally you should upgrade to the twin disc front end but i have yet to find a decent pair for a cheap enough price so i have still got the single disc.

From what i read the 250 feels underpowered for its weight and the 400 apparently makes a fair difference so it is defiantely worth keeping an eye on that engine, its look decent actually. Should be wel easy to get running again too by the sounds of it. Also, (you dont 'have' to i suppose) but on mine it has been changed on the log book to a 400 and is now taxed and insured as a 400cc just to stay legal

Ahh! I really dont want to wait 2 months Ill give them a ring tuesday if you have no joy. All the best!
____________________
1980 Suzuki TS50 ~ 1984 Honda CB400N ~ 1992 Triumph Trident ~ 1998 Suzuki Bandit 1200

[Ant132]

Good news, found a place that has the piston rings in stock. John Oldfields in Southampton Not sure what the delivery times are like though.

Havent done any more to it today, just been out and bought a few things i need. Valve grinding tool, feeler gauge etc. All ihave to do now is order the rings and a gasket set and im well away.

Just one thing though, Is there any tell-tale signs that a barrel has been re-bored because there doesnt seem to be any markings on my piston. I was expecting STD or something but theres nothing.

Ant
____________________
1980 Suzuki TS50 ~ 1984 Honda CB400N ~ 1992 Triumph Trident ~ 1998 Suzuki Bandit 1200

[monkeyboy111]

well done thats good news!

I'm not sure but if it was re-bored it would have bigger piston or rings! so you can only tell when you get the new rings! but i might be wrong!

Carl

[Ant132]

Bought a valve grinding tool from halfords and was having a go with it today. Not entirely sure of the correct way to do it but it seems to have tidied them up at least. I'll test the seat when i come to re-assemble and hope for the best.

I found my vernier gauge today aswell and measured the pistons. I was looking for 62mm for standard pistons but it was 71, after about 10 minutes of thinking WTF, I then realised that i reading the section for the 250N, and sure enough the 400N spec said 71mm.

Anyway, heres what i have done so far, just cleaned everything really. Got the old gaskets off and excess oil in the fins. Bore is real smooth and the pistons look in real good condition so im not going to be too worried about putting them back as they are. Just new rings and gaskets will do.

https://i101.photobucket.com/albums/m62/ant-147/DSC0001510.jpg

https://i101.photobucket.com/albums/m62/ant-147/DSC0001610.jpg

https://i101.photobucket.com/albums/m62/ant-147/DSC000179.jpg

My bike looking very sorry for itself.

https://i101.photobucket.com/albums/m62/ant-147/DSC000198.jpg

Im going to soak the parts in parrafin or something incase theres any excess on there. With any luck i will be done within the week depending on parts. Im also waiting on a new back wheel, last week while i was riding the sprocket circlip snapped. I managed to get it home with a jubilee clip from halfords but its worn away at the hub so ive just bought a new set of wheels for the rear with full sprocked assembly for £26 all in.

Ant
____________________
1980 Suzuki TS50 ~ 1984 Honda CB400N ~ 1992 Triumph Trident ~ 1998 Suzuki Bandit 1200

[Ant132]

Piston rings and gasket kit came today, so scracked on with the rebuild. Everything went lovely and smooth, piston and rings were a f*cker to get in the barrel without ring clamps but got there eventually. Another thing on my shopping list aswell is a valve spring compressor, had to struggle with pliers which took ages.

Anyway, everything back in and lubricated. Head on, all timed up and valve clearances done. Last thing was cylinder head cover, guess what! Bolt snapped on the cover. *@!!//:###!!!

Took me from half 2 when it snapped, until half 6 to solve it. Never had any parts to do it but evenutally found my old hellicoil set which i used after drilling it out. But then when i was using the tap and die set, the bit snapped in my freshly drilled out hole. So i was back to square one! (I werent laughing at the time)

Minor hiccup solved and on i went, all back together in no time after that. Carbs on, exhaust on and sealed back up (had a bit of a blow last time) So came to start it and after a few revoultions it fired up. Took a while for it to idle smoothly (im guessing it was due to assembly oil fouling the plugs) but sure enough after a few minutes she was back. Idles lovely and smooth, alot quiter and seems to feel as though it has alot more 'oomph' Revs up quicker too, seems more reactive on the throttle.

Couple of things preventing me test riding though, firstly the rear wheel still isnt complete, i need a chain adjuster bolt as the old one bent after what happened with the sprocker circlip. New wheel is on anyway, new bearings and seal. Sprocket is nice and tight too, nothing to worry about with it now.

Last thing, i order two new handlebar grips as the old ones were really worn. Although despite them both going on really easily, the throttle now doesnt return when i twist it. It used to be really smooth but now it is stiff to turn and doesnt return willingly. It has to be manually turned back. Does anyone have any ideas why this could be? (Ive checked the cables and they are free and lubricated, operating fine)

If you are still reading, then thanks! Ant

Edit: Whoops, nearly forgot my most imprtant question. When running the bike sounds quire 'tickety' (as in ticka-ticka-ticka kinda sound). What could this be? Cam chain? Valve clearances? (Too big? Too small?) Help appreciated as always!
____________________
1980 Suzuki TS50 ~ 1984 Honda CB400N ~ 1992 Triumph Trident ~ 1998 Suzuki Bandit 1200

[monkeyboy111]

Well Done on the engine! there are also something that is going to break or be stupid to get off but you got there!

Not sure about your grips! if it isnt cables it must be the grip its self.

Ok the tapping noise you can hear is the valves tapping as the gap is to big. take rocker cover off and check!

Carl

[Ant132]

Ta mate, bad news on the cylinder head cover bolt though. Its not holding and when ridden the oil seeps through the gasket. Its been helicoiled aswell and the stem is just too thin. So i need another rocker carrier now

Ive sorted the grip now, i just peeled back the new throttle grip and sprayed WD40 into the plastic tube and got any crap out. Springs ack lovely now. Wheel and chain is all sorted too, only thing holding me back is the damn rocker carrier. Ah well, could be worse.

The tapping noise ended up being camchain rattle, all i had to do was slacked the cam chain adjuster nut and re-tighten it. I checked the valve clearances twice and they were fine.

Not sure if you got my PM mate, but just wondered if there is a spare rocker carrier going for sale on your spare engine. No worries if not, theres a few being broken on ebay so bound to find something eventually, 'tis better than the 131 euros that CMSNL want

Ant
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1980 Suzuki TS50 ~ 1984 Honda CB400N ~ 1992 Triumph Trident ~ 1998 Suzuki Bandit 1200

[monkeyboy111]

oh bit of bad news my rocker carrier is dead aswell no use atall sorry m8.

[Ant132]