CB400 Four special (Mr Sinx II )

[Northy]

The seat alteration was genius! 

Thanks   but I  did about 35  years ago ......trouble was I couldn't remember how had bolted all the bits together. I've over engineered the rubber mounts to much and need to simplify them (at later date or just leave it  .

 

[Northy]

Ok mudguard arrived  from  D&M engineering and I made a quick a fork brace from stainless plate , as lot cheaper than the £112  for cb400n fork brace on the net . It shouldn't really need it as i've double disc but it will give bit more rigidity to the front end . Also provides more secure location for the brake line clips 

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So thats my front end done , but no strips/decals yet as still not decided on what they should look like but should be pretty easy to do.


So I slapped a spare tank on it for road test and its safe to say this is a horrible colour combination
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The fairing still looks too big for the bike and may be changed at later date , the bike sits very high . I took it for a spin around the block to "test" it ,to find that :-

1) Clutch adjustment way out  (now sorted - has new plates/springs so will need to bed in)
2) Running too rich. Gets to 3.5 k and splutters (later removed some very sooty plugs, so standard jets going back in from 98)
3) Number 1  carb leaking the all new o ring had split , may have caught it when fitting, last spare fitted.
4) Oil leak from rocker box around no 1 area. In other tests the bike was on it centre stand, the leak occurred when run on it side stand . So looks like need to remove the rocker box off to see whats happen in there , at least there's oil up there.
5) Brakes need to bed in 
6) Steering and ride feel fine.

So tank to  still to do , need fuel tap but suspect the yellow tank may be donating one. 

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Side panels  to  add but need some  Cb400 four  logos or something .....going back to 80  I used letraset letters and number , might get some vinyl ones this time   

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So nearly there but not , really disappointed in the rocker box leak it was "glued" into position with a casing compound.





   


 



 

[Northy]

OH the  funny gaps in the tank paint work , luckily I had something to cover them up with 

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Needs lacquering  and going off etc ......thats another  week of spray ,spray,waiting, rub down, spray , more spray , more rubbing and waiting.


 

[mattsz]

OH the  funny gaps in the tank paint work , luckily I had something to cover them up with 

We knew you had something in mind there! 

[taysidedragon]

I like the colour scheme. Looking good.

[Northy]

Well  from  pile of bits , frame , spare engine and wallet shrinkage bits .......Mr Snix  (mark II) . Still things to sort out.

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Running smoother on standard jets, with proper coloured plug which is odd as I'm running pod filter (albeit oiled) Pulls cleanly up to 5k .....running it in , honest ! 
Does "smell " warm, combination of tight engine, engine paint going off and warm weather
Brake still feel very wooden.
Front end is too soft
No oil leaks ....had caught the rocker box gasket


There are number things which have arisen since adding all the bits together and riding it.

The 2:4 seat is slightly narrower at the front so some bits on the tank I thought would be covered up ...aren't.
The cockpit fairing is mounted to the headlight bracket which is rubber mount so it wobbles. 
The Speedo is a pattern Cb400n part and is too long (brake line also tad too long as well) further highlighted by soft front end
The massive number plate has to go (looks like a air brake )

Ohh don't just run the engine breather tube into a plastic bottle inside the unused air box , you get steam rising from under the seat.

So is it finished ...nah never , the original one took a number of years to perfect .Then it got used,abused and end up used a commuter.

This is an attempt to go back in time , ie what we did the 70/80's with bikes, we all modified them. I could have put all the modern stuff on it but I might as well got a 1998 honda CB400R (supersport) and tarted it up but where's the fun in that  :-) (ohh that  might be a interesting project  )_ 

Needs some logos, decals, a clean to remove grubby mit marks & dust, tank needs rubbing down and need to put some more wadding in the exhaust . Its too loud for me so at 6k its going to howl a lot.   

 

 

 
 

     

[SteveD CB500K0]

You are right about ”this is what we all did to our bikes”. We couldn’t wait to rip them apart (see avatar)

That does look good though.


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[Northy]

Thanks for the comments and I think this will be work in progress .

Still very aware it runs very hot .... so just given it some short runs in the cooler parts of the day. I was so paranoid had to check it oil was getting to the top end by removing a tappet cover ....its was and duly ran oil all over the engine. If there was an issue it would have gone bang or screeched to a halt by now. Thinking of putting 20/50w oil in there,currently using 10/40 but it semi syn and well runny when warm.

Plugs are the right colour and the thing is slowly getting better ie not getting so hot so quick. Engine pulls really well. Everyone loves the pipe but still too noisy for me   

Got puncture in rear 1/2 mile from home today ..nice new nail      rather put a hold on the running in as only had front tubes in my stash.
Also one side panel cracked at the top , was secondhand to start with.   

Modified the rear wheel spindle , fitted a longer one due to dresda box section swing arm being fatter , still tad to long 

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Then made simple stop for the rear brake lever, its just a bit ally with offset holes so can used as a cam.

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Next up the rear under tray will chopped back , doesn't need to be that big as its not carrying any weight and paint outside black.

Brakes slowing getting there.

Its making me smile    especially when a guy you don't recognise, says "Hi, Northy I remember being chased by that bike back in 80's" not seen him since the early 80's but its that bike they remember.

Or maybe my 40 yrs old oxblood red leather jacket, which has been adjusted to fit again (may put few pounds on over the years)


 

[pistonbroke 66]

Take a bow that man, some cracking work there!

[paul G]

Great stuff keep up the good work.

[Northy]

OK folks bit of an unpate .

Bike is now run in with a some 600 miles on the clock ...might not be long enough for some but I'm not  red lining it yet

Still smells hot but the cooler weather has helped and the paint on engine is slowly cured (did put a lot on there ) trouble is dried with bit of dust stuck onto it

2 rear punctures ,  one 1/2 mile  from home (nail) the other 20 mile from home (new screw) and was 3 hr wait in the heat

Replaced the rear shocks with some softer ones much better but the front damping is poor and soft.

Front brake still not fully bedding in, even took them off to check ..too hard a material may be but better than standard set up. G getting better but does show up the soft front end. 

Piccy of revised rear mudguard in plastic replacing the S/S  item  (lost a good kilo there) and slimmer softer shocks
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Have a dimple in my seat .....odd talking point but its where the foam was injected in at the factory

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Added some bling to engine (thanks Peter) finned covers

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The engine is going fine, really takes off and revs freely and 60-80 acceleration is impressive. Think I've got the jetting about right with a smooth clean pick up .That exhaust does have great rasp at 6 k ...still tad to loud.

The gear box or should I say the rear sets are making for a slow down shift. I've adjusted them and can't quite get it balanced, adjust one way and upshift are the issue. Think the arm on the rear sets is too short and I'm not get proper leverage (or weak spring in the selector mechanism)

However the biggest issue I have is a tiny oil leak from the drive sprocket oil seal. Not from the shaft but between the case and the seal and its bloody annoying. Its only a few drips every 50 mile but still should be happening . This seal was new (all new seal/etc in engine) so why should leaking between the casing, its not distorted. Can't over pressurised in there.

The seal has a locating stub which means removing to replace is a pig split the cases or refit one with the location stub ...anyone done this . For time being I going to try some sealant around it.

So I've the forks to play with , tidy up some of the wiring and oil leak to sort out
       

[K2-K6]

Sounds like you're getting it debugged and how you'd like it.

Your oil seal leak,  as you state it shouldn't really have any pressure in there so maybe worth checking any breathers are OK first to avoid unneeded work.

It's unusual to get a good / competent seal from using sealant on the outside of a leak so may involve more extensive intervention if you can't get a simple cure.

Presume you used new oil in the forks when building?  Otherwise it's definitely worth a change to get better damping control. I use the moto-x derived oils as they are generally good quality for suspension control, with really good anti-foam properties that give consistent damping.

[Northy]

Oil leak now sorted

Ok I cheated by putting some TBS (Thermal Bonding System) around the seal. Its a thermal epoxy glue which works up to 120c so that should hold for a few years ...fingers crossed.