Honda-SOHC

Ok Folks , brought a 400 from mate , never do that with recorded mileage of 9k (mot's  to back it up ) but he couldn't  get running right . I got running better but its gutless and has other issues.
Here the symptoms  :-
On start up smokes , but clears .
Pulls fine up to about 4.5 k then misses ,no power can rev it up to 8 k but feel like it missing on one pot, hot or cold
Not go above 60 !! feel like sock up the exhaust pipe
Using oil but once warm there no smoke or horrible noises
Oil is blacken within 200 miles
Compression 25psi lower than my other 400f on no's  1/2 same on 3/4 as comparison only.


So how you going through the thought process ...and coming to a conclusion but first this is what has been done, with no effect :- 
Swapped over Coils from running bike, carb sonic cleaned  checked x2  and then swapped over with another set , electronic removed back to points, new air clean and plugs, advance retard mechanism  checked 

However you I can hear shouting it the valve steam seals !! ...that covers the startup smoke and oil usage  agreed  so lets whip the head off have looks see. Expecting  broken rings as well 

First this head been of before ! and came  off to easy and the exhaust ports are very sooty

Umm  lots oil  so much the carbon comes off easy , note  one no.3  pot  is less oil and this confirmed by the colour of the plug
head


piston tops



So next was to remove the barrel , expect a ring to fall out ...hope all in one piece and then notice the are piston 0.5  O/S.


Bore with honing marking in place



So there looks to nothing to much wrong with piston / rings and quick check on the ring show all OK  and no slop in  bores .... could have been rebored wrong ?

OK move back to valves and just whipped one out  and it clear the valve stem seal are shot  see pictures but also note the perfect face on the valve  (plus loads of oil)   





So OK stem seals can account for oil on start up, oil usage,oil in bores (?)  but it would still run Ok and given that there no oil appears to burning pass the pistons.

However I cant see that the seals would have such a dramatic  effect on the power of the engine . Ok it can suck in oil and air and weaken the mixture but never this bad or has the thing not run in yet ?         

Tomorrow I will check the bore/piston and all the valves 

So what am I missing (apart from few brain cells !!)



   







   

Crank is good , see piccy

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Big ends look like this , worn but nothing nasty
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Just new shells needed.All david silver was offering  at stafford was £1 delivery for order placed at the show and I've long list of stuff I need could remember it all.

Set of cases nearly ready for painting , mainly used paint striper , small wire bush  attachment , then wash in thinner , will need another clean [/URL][/img]

Been working on the manky side covers ...getting there slowly
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Right any purist please look way now before you go mad and say why wreck cb400f and make special out of it .

OH also long thread alert …if your bored just look at the pictures ;-) Oh will be lots of typos as well   

Why a 400 four ,well back in 70/80 I created this and number of variations and still had standard yellow one VKK 333S.


 I sold the bike in 1993  for £350 plus a mountain of spares (DOH !! ) well the engine had done over 150k, was on its second frame, iffy wiring and even the ARE alloy wheels where a bent in places. Ironically nothing I couldn’t fix now. So some 30 yrs on , my spannering skills are better than that poor cheeky kid on the “flying tampon” as mates  used to call it. Its was called Mr Sinx, after our cat (bloody vicious thing!)

Well at the time of writing I have two other 400f that are rolling restorations. 2 frames and yet another mountain of part worn 400 bits. Also over the last few years done a few restoration to high standard and a couple of specials.(read I’m handy with spanner and a picky sod too)

So this will be a recreation of Mr Snix but I might move away from the clip ons etc , so more like the Mocheck Harrier (to save my back & wrists). So I’ve already have picture of how it will look in my head and I know what I need but finding them and making them fit is the fun bit  (need a set of Alloys)   

So where does ones start with just frame, engine and plie of bits …the carbs of course. I needed a clean set for one of the other bike which was suffering odd running.(turned out to be the coils). The Bike bits had been sitting for excess of 7yrs in  garage (working one with sooty diesel, brake dust and damp etc )  So the carb where stripped right down 




Tip one , don’t disassemble the rod mechanism if don’t have to. The rod that runs across the carbs to link them together runs in two bronze bushes. However there is also a brass pin in one mount that hold the bush in place and locates pin on the rod. To remove the rod you need to drill out this brass pin or the bush with break up if you try to remove the rod. However drilling out the pin a PTA its only 3mm dia and can easy go into the ally mounting. See picture even drilling the pin didn’t help cracked anyway!!
So some clean carbs , a with re-plated metal bits. I used stainless bolts and this not going to standard anyway.

 
Good job I've spare set of carbs

So next engine, I wasn’t expecting great things from this. The clock said it had done 43,000 miles and it showed signs of previous split cases and nasty bodges. As I was  stripping this down to last bits, I didn’t bother deep cleaning it before hand


Ohh err


The thread on bolt that locks cam chain adjuster had been chewed up badly but managed to heli coil it. Phew

Spot the odd one out


Two head bolt where finger tight and the cam chain was starting chew its way into the adjuster (they all do that sir). Which is why there was no wear on the guides.
Then the good news the clutch looked like new. I even found my old home made clutch holding tool in the not use often “tool box” last used  25 yrs ago



The primary chain, is very sloppy and need a new one of those. The bore was OK , with marking where the piston had been and still on standard piston bit all looking a bit tied with one broken ring. I measured them all up and there just outside the recommended tolerances, could put new std piston and new rings  and it would run but it deserves a rebore.





So do I go for the oversized 54mmbore kit or just take it 0.25mm OS. The cost using kits from Cruzinimage_uk is the same. I tempted by the big bore (sounds good and gains brownie point when talking bollocks at the cafe)  but then reality kicks in and its only  on a 400  if I need to go faster there’s an modern 750 in garage.   However welcome your thought on this ??.


There was much sludge in sump and bottom of the cases but hardly any metal bits …all good.

Main bearings all Ok but the big end showing wear so they will be replaced ….bloody expensive at £10.74  per half shell ….


All the valves have been removed and the head looks in fine shape no damaged fins, rocker spindles with bit of wear and valve seats good.Cams  all good , wear but nothing  bad.
So no sheared screws or bolts, expect general wear no nasty surprises and only two threads required a helicol. I do them when I see on strip down as the stuff is going to be cleaned after so any bits of ally get washed away.  Not bad at all it would have run no doubt but no very well.

Tip 2  Rotor removal is required for replace the end seal and best  done once the crank removed,. you can’t do without splitting the cases due to the lip on the seal. You could take a hammer to it, dig out the special tool (if you have one ) with a 18x1.5 thread it to “pull” the rotor  off. However the thread a size is the same of many car sump plug or Lamaba sensor plugs available for £2.  Sorted !!   


Next ……the case of clean the cases!!
     
Got quoted £140  to vapour blast the  cases,head. barrels etc  .......Sod that, out with chemicals.

Jorge , agree with Julie. 

Sounds like the bike is not too bad , picture would help.  Need to decide if the bike needs stripping down or is useable as is. Suppose The getting the engine going is key.
Remove plugs , drop some oil on the bores and turn the engine over by hand first , if moves you move on to stripping the carbs and clean, drop the sump (20  year of muck will be waiting for you to clean out ) and change oil filter and oil. Renew all plugs . Turn it over (borrow battery) check you've a got spark. Then add fuel via a dummy fuel tank . If starts its will smoke (oil in bores ) but if it carries on you've got issues . Turn it off , allow to cool , if on start up it still smokes then it a engine strip (valve seals 90% of the time) . If doesn't smoke then I  start on tappets, timing etc  moving on to the running gear. Your front brake will be seized !!!  they all do. Just recommission two .....one with smokey engine on start up ...currently working on a thidr engine.
   

Is that a Mocheck?


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No just standard motor, and lots of fancy bits ,it even had 4 in 4  system added at one point , the ground clearance was awful. Ended up with double discs.However this time round with more of the mocheck look (more upright position) and 4 into 4 system that works. Did about 150,000 miles on that thing by which time things had well worn out
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