Honda-SOHC

Hi,
Many moons ago I bought a 400-4 and rebuilt the engine.  it was my first attempt at refurbishing a (bit of a) bike - and it worked out pretty well.  The engine worked well - and after lots of help from the lovely peeps in this very forum.  However there were a few bits I wanted to do better - and a few threads that need repairing which meant I wasn't totally happy that I should ride it too much before I got to it.  Meanwhile I have to confess I have refurbished a Suzuki GT550.  Sorry (!).  But - now I am back to my 400-4 - and am currently stripping the bike completely and doing the lot - including rebuilding the engine sorting the niggly bits I wasnt happy about (oh - and a new clutch which I should have done first time around!). 

So - to my (initial!) question.  I'm going to get the frame and some other bits powder coated (I hoped to leave it with its original paint - but now I can see it clearly - its not original .. and badly applied .. so a recommended place in Redditch will get a call soon!).  The steering head bearings (balls) all look great - but clearly need to be removed from the frame and steering stem before the powder coating - but I have no idea how to remove them (rookie question I'm sure ... but rookie I defo am!!).  Can someone suggest how best to do this?

Thanks everso,
Dave.

Hi all,

Does anyone know the how tight the 400-4 oil pressure switch into the oil pump should be?  I have a slight leak from it (my only leak after the rebuild which is a bit of a relief!).  I gather the thread is tapered - the top part of the thread is pretty corroded, indeed the switch itself looks a bit sorry for itself so as a precaution I'm replacing it - but I cant find any mention of torque settings in manuals (so I want to stop it leaking, but not strip a thread, and I don't want to use any PTFE tape or anything nasty like that to get a good seal).

Thanks.

Hi,

With the invaluable help of members of this forum I have completely stripped and rebuilt my 1976 400-4 engine - and she lives again! It all started with some weird grinding noises (not to mention cam chain chatter and primary chain slap) and the urge to remove all the horrible paint/lacquer that was peeling and  generally looking a right mess.  So she was stripped right down (and soda blasted) and the primary chain replaced (along with the cushion rubbers as advised on this forum) plus the cam chain was replaced together with the adjuster arm (a new one from DS as mine was completely seized and worn away),plus the slippers.  All the engine seals were replaced, but the bearing shells all looked fine so they have stayed.  At the top end I replaced the piston rings (all were well outside tolerances despite being 1mm o/s rings - so clearly at least one rebore in its time (indeed it was clear that the barrels have been off - but I dont think the bottom end has been touched in its 38 years). I also replaced all the valves as virtually all were hammered - literally.  They looked as if they had been ground, but I suspect in doing this the hardened 'crust' have been removed meaning that the tappets have been slowly wearing into them (I replaced the tappets too) -so they looked pitted.  And valve seals of course.  Something I spotted when putting the rockers back in (and not mentioned in the original workshop manual that I am fortunate to have) was where the springs that keep the rockers apart should go.  If you get them wrong the tappets dont quite line up properly with the valves - I noticed that the way around that they had been mean that was indeed the case and I wonder whether that too lead to undue hammering of the valve stems (perhaps an expert can comment on that?).  I just looked through my photos of the strip - and annoyingly didnt take a pic so cant show you which way around I have them now!  I have just balanced the carbs (I did also strip the carbs and cleaned them, one float was 'sticky' due to the hinge pin being slightly bent and this meant I used to pour fuel over the floor if I forgot to switch off the fuel tap - not any more!) - and she's running sweet as a nut.  So - ready, I think, for an MOT next week.  I have to say I am well chuffed having never done more engine fettling than replace a GT380 piston many, many years ago when I inadvertently holed it after fitting expansion pipes without re-jetting!).  I have absolutely loved it.  Yes there have been frustrating moments - but I've said before (and I wont stop saying it -so tough!) that this forum has helped me no end.  Its so good to look at (and listen to) a sweetly running engine and to think I have stripped it right down, replaced stuff that needs replacing, rebuilt it .. and it works!  I plan to do more over the years - but this one will always be the special one.  And to celebrate I attach a gratuitous shot of said bike as she is now and a few of the many, many in progress shots.

The reason I ask is that I remember reading somewhere where someone was concerned that repeated torquing and untorquing bolts reduces their life (so they didnt like to use Platigauge).  But I wondered whether you really need to torque them all the way to get an accurate measurement?

Some weeks ago OddJob suggested that I post a picture to show a worn vs new Primary Chain ('76 400F).  I received the new one from DS today - so attached is that pic.  As you can see the new one has no links touching when laid as a 'tank track' - the worn one has almost all touching (any touching suggests an amount of wear - clearly this is well shot!).  Furthermore - when you grab a few links of the worn one and pull it apart you can feel some play in the links - needless to say no play in the new one.  I hope someone finds this useful.

In various places in the manual (76 400-f) it mentions using liquid packing on mating surfaces (eg. the crank cases where there is no gasket).  Previously someone has used some red stuff that has gone brittle and I find bits all over the place (some in the sump).  Wanting to avoid this again, what recommendations can anyone make? And when I install new gaskets (with clean faces) would you recommend using it (or other stuff) with gaskets - or just stick to using it just where the manual recommends? Thanks.

My pistons are all stamped with '1.0 mml 5' (I think it says).  Does his mean they are 1mm oversized?  I need new rings (typically the top one on all has a gap that is on the edge of the service limit) - and I was about to order some when it occurred to me that maybe the pistons are over size as on measuring they appear larger than the manual suggests.  I guess that stamp must mean something?  Any idea anyone?

I have a 1976 400-4 (that'd currently in a state of clean-up (re-furb is to generous a term for what I'm doing!).  But - before starting work on her I found that in some gears (not always the same gear - no consistency) I could hear a strange rumble/scraping sound from the gear box / chain area.  At higher revs (ie. 5k and up) it goes.  Also - if, when I hear hear the noise, I quickly shut off power and re-apply it - the noise sometime goes. It's very odd and I cant for the life of me figure what could be causing it.  The clutch doesnt slip (indeed have had that out and checked it over and it seems fine (one plate - the inside - going out of tolerance - but I have swapped them around to be fair  .  I did find that the 2 bolts that hold the plate on the front chain sprocket are missing so wondered whether that plate has been moving about and making strange noises) - but this sound is noting I've heard on bikes before - indeed didnt hear when I first had the bike (have had to repair the rear tyre - could I have not put the wheel back on properly?!).  Any ideas / thoughts gratefully appreciated as I'm at a loss.  Thanks all.