classic motorcycle forum

Soooo, I hopped and skipped into the workshop on Friday afternoon, full of the joys of spring!

First thing I did was remove the larger half of the head-steady so the bracket that goes onto the head would be easier to fit...
My Dad's choices here are clear... this nut is NOt coming undone!


Then I undid the Rocker  box again so I could document the assembly process properly (as promised).
First: Assemble the rocker arms and bearings into the bottom half of the box like so: Note the "outboard" bearing liners have been pushed "down" out of the box body, so the rocker arms have next to no end-float:


Gently put the top on.


This is what the push-rod side of the box should look like - the rocker-arm bearing liners will be proud of the box face:




Fit and tighten down the "inboard" fixing screws, This will lock the "inboard" rocker-arm-bearing-liners in place, but allow the "outboard" bearing liners to still move: when the cover is fitted on, it won't meet the box edge, because the stubs on the inside face of the cover are meeting the outer end of the rocker arms: 


You can see the gap all around where the cover meets the box.


Tighten up the cover.  This pushes the rocker arm against the bearing liner, and pushes the bearing liner into the rocker box.


Most of these engines have a single-sided wing-nut/bolt for the rocker cover, but I just have a plain set-screw (bolt)


The bearing liners have now been pushed into the box, and the end-float of the rocker arms is limited by the stubs on the inside of rocker cover face.


Note - this bearing liner (exhaust side) is still a little proud.


Now fit and tighten the "outboard" fixing screws to lock the outboard bearing liners into position.


The assembled rocker box: the rocker arms should "flop" about freely, but without rattling around.  With that in mind, it's worth remembering that they only need a small-ish amount of movement  in actual usage.


Fitting the Rocker box to the Head:
The lower valve covers go on first, then the Rocker box:


The Washers on top of the Rocker box are spacers to allow the head-steady bracket to fit easily.


Head steady bracket:


Rocker box fitting bolts - getting these aligned is a bit of a git:


Test fitting the upper half of the valve covers:


Ah - yeah... the oil feed banjo fitting - that would have been easier to fit EARLIER....
I may need to find another one of these, it's brass, and the hex "head" is knackered.


And as for these little gits....


These are the oil feed into the valve-guides, and they are a pain in the arse to fit, so I took the Rocker box off again to fit them!


They're just  a push fit into small holes in the head, so sealing them wo'nt happen. :roll:

At this point I was pondering something and happened to be rolling the crank back and forth....

when I heard and felt a distinct "clunk" coming from the movement of the crank. :wtf:

Video:
https://youtu.be/_VnexesDQKA?si=NvSMuXI4gSz3eD10

So... I started stripping everything down again! GAH!

A rather unpleasant discovery  when I took the barrel off was this oil weep under the base gasket:




To be honest, I'd had a nasty suspicion that I'd seen dirty oil at the bottom edge of the barrel, looks like I was right.   I think the 3Bond had soaked into the gasket, or maybe it just wasn't thick enough??  Don't know: but when I fit the new base gasket (I'm going to make another one because this one is very tight around the barrel base), I think I'll use Blue Hylomar instead of 3Bond, maybe, don't know, we'll see.  I'm not impressed because this was weeping with zero provocation whatsoever, there's not even any crankcase pressure at the moment - the timing side is still completely open so this was weeping simply through capillary action.  It is interesting though that the weep lined up with edge of the barrel base that is broken (see earlier photos).  I think pulling the gasket away from the barrel base may help, hopefully!

This time I took the barrel studs off before the piston - makes it easier to get to the gudgeon pin circlips.


Another shitty video...
https://youtu.be/mW1prhFqC4U?si=zz84myipwydojLNr

(Apoloies about the portrait videos, I set things up in a hurry, will do better next time!)


So - the cases were split again!



I did figure it out though...
THIS:


is scraping on THAT:


I think the big-end-shaft nut is hitting the main bearing liner locating screw:


really not sure how the design would even allow for that.. but, it appears to be what's happening. I can only assume that previously, the thrust washer on this side was thick enough to create a clearance: IIRC the two thrust washers fitted were a 0.040 and a 0.050: because I've fitted a new liner on the output side the clearance in the cases is (I think) now a tad smaller, so when I did the crank end-float I ended up with slightly thinner overall thrust washers fitted.

I played around with the thrust washers: simply moving the fitted ones around (ie, moving one from the output side to the timing side), and this did seem to create enough clearance:

Video:
https://youtu.be/iPZ7o_STyd0?si=gztkDB_r870HtbDh

But, I think I'm going to do some more checks before I start the assembly process again: I'm going to make sure that screw is down as far as it will go, and I will likely do a touch of grinding to take some metal off the top of the screw head, just to increase the clearance a bit more.
Then, I'll fit a thicker thrust washer on that side, and re-do the end-play by fitting the correct thickness thrust washers on the output side.


Funnily enough... the output side of the bid-end shaft has the nut and shaft ground away slightly in a fashion that would indicate that this issue has happened on the other side.  While pondering this over the weekend (I've thought of nothing else), I did wonder if maybe the fly-wheels got swapped over when we replaced the big end bearings, but I'd be very surprised if this was the case, the crank wasn't completely disassembled: the output and timing shafts were not removed from the wheels, (and it's not a reversable assembly), so I am slightly confused.


Output side crankcase cleaned up nicely:


This stuff rocks!



So - all this weekend I've been pondering my options.

I think I'll start, as mentioned, by trying to take some material off that locating screw (won't be much, just enough to make it less of a prominence),
cleaning up the rest of the sealant from the cases,
Re-doing the crank end play with a thicker thrust washer on the timing side to ensure clearance,
Make a new base gasket (maybe with a thicker bit of paper... not sure really)
Then restart assembly.

few steps forwards.... several steps backwards.... hey ho...  it's all a learning experience!

Interesting, I always thought the petrol engine would require more finning because it burns hotter than cool running dope.

Thanks - satisfying to read to the end.

Leon

I think things are going well... (and a lot faster now the weather is warming up!)

So - last night I got another couple of hours in the shed and....

Dribbled a bit of oil into the cylinder to help the initial ring seal and checking of compression


I got the engine spinning a bit by hand and then wiped most of the excess that had gathered at the top of the barrel.

Then it was time for some heat!


The last time I tried quenching copper it was some brake-line crush seals and I massively over-did it and turned them into slag....
So this time I played the heat over the gasket until I had a glow chasing the heat around the ring, then chucked it straight into the water


I only did one side, mainly because I really did NOT want to over-heat the thing and warp it out of shape, so, we'll see how it goes.  If it starts blowing very quickly... at least I now know how to get at it.

Shiny side up!


Buttoned up again.


I did try rotating the engine with my thumb stuck over the plug hole..... and there's definitely compression there!  Whether there's enough compression only time will tell....

So - time to assemble the rocker box:
All the bits:


First I cleaned up the threads for the rocker adjusters:


Stuck the cap-heads on the valve stems : (This is exactly the sort of thing I would forget if I hadn't put ALL the parts into little trays of associated parts, as seen above, I would highly recommend this practise if you're doing a job like this).


The exhaust rocker had a little bit of corrosion on it's shaft, (phnarr), so I gave the shaft a little polish (ooer!).  The inlet seemed fine.




Assembly of the rocker shaft with all their annoying little roller pins in situ:


I dribbled a little bit of oil into the roller-pin bearing assemblies to get them started, they definitely felt dry when I was first checking their movement.

As described earlier in the thread: the Rocker box assembly is done by pushing the bearing liner for the outboard (push-rod-side) as far out as it will go, fitting the top-cover of the box, then donig up tight ONLY the inboard screws, so the inboard bearling line is locked in place, and the outboard liner is "just" moveable ... then screwing the outer cover on, and the bosses on the inside of the outer cover then push the rocker arm into the box: pushing the outboard liner into the box just enough.  This means the rocker arm "end-play" is automatically controlled and is hopefully minimised.  I may actually re-do this process with a lot more photos next time I'm in the shed just to make sure I've done it right....

First thing to go on is the lower halves of the valve-covers.


I had to spend a bit of time trying to figure out where the washers on the bolts that hold the rocker box to the head (only 2 of em!) were supposed to go.  I didn't make an exact note of this when I disassembled the bike (d'oh!) but I think I worked it out eventually.  The complication is that there's also a bracket fitted above the rocker box that attaches to a head-steady which bolts to the bike's frame at the headstock, so I was trying to figure out if there should be a washer under the bracket, or 2 above....  I'm pretty sure there's no washer under the rocker box, it mates directly to the top of the head.

And that is where I ran out of time for the evening.  :roll:

I'm currently pondering the idea of trying to seal the valve gear with the 3Bond - it's not designed to be sealed (it's a shale-track engine, weeping oil all over the place is a design feature), so it's a problematic process at best.  Especially since I may well be placing and removing things repeatedly....

Food for thought over the weekend anyway.

NEXT TIME:  Rocker box fitting and TIMING! (well, hopefully!)

Nice going.
Probably an optical illusion, but is that piston circlip fully seated in it's groove all round?
I've been caught out before where the supplier fitted round section circlips in a square section piston groove, and they didn't seat well.