Troubleshooting a JAP Special

[cardan]

Love the oiling concept and the link with your dad. Keep up the good work!

Leon

[Rockburner]

Just a brief status report.

The sludge trap has been soaking in white spirit for a couple of weeks.



And, with some gentle encouragement....


All the little discs seem to be more or less sludge free and loose enough to rattle, just about.

So, its  all, i think, ready for reassembly once i get back from Latin America.

[Rockburner]

Gulp.... here we go....

Time to start the assembly!

First I checked the locating of the crank oil feed quill, which, for some reason, my Dad had left out of the engine when it was last buil!  How the big end was getting oil I have no idea.....
I only ordered this recently, I had no idea it was supposed to be there until I spotted it on the Speedway Service list of parts and wondered what it was....  If I hadn't lost the little seal from the timing cover and had to order new ones I'd never have known about this part.



I also checked the crank-shaft oil feed line was clear:


Yup!


I then set up the timing side crankcase on a few blocks so that it would sit easily, cleaned up the remaining lithium grease which was on the thrust washers on the crank shafts, fitted the bearing cage and rollers on that side, and dropped it into the case:


Fitting the bearings was a lot of "fun" - they're soaked in R30 and have a tendency to try to pop out when you're pushing the next one into the slot: this little so-and-so made a bid for freedom and I lost 10 minutes hunting for the git, eventually I DID find it on the floor, I think it somehow ended up under my shoe!


Second set of bearings all in:



I then cleaned up the case mating surfaces with Sika Wonder Wipes,



Then again with meths on a clean bit of cloth.

Just a fraction of the blue paper and wipes I went through....


The Threebond was a lot more fluid than I was expecting, and I lost a bit of time hunting for a nozzle amongst my other tubes of goo - unfortunately couldn't find anything to fit so I had to just dispense from the tube.
I think this was a little too much - but there wasn't a "huge" amount of overflow on the outside of the cases.



Note that on this side of the cases (the Timing side), there's a "wall" or "lip" on the inside of the mating faces - this provides a locating key for the other side and a partial "labyrinth" seal, it also means that hopefully there's a lot less chance of the Threebond getting into the inside of the cases if you apply it to this side of the cases (as opposed to the other half), well - that's my hypothesis anyway...

I fitted the other side of the cases, used the small bolts to hold it together and align them, then fitted the workshop legs and cleaned up the small amount of excess 3Bond that oozed out.  (the Wonder Wipes were very good for that).

The next step was to fit the output side crank seal - this is a modification to the original engine, I'm guessing from F500 racing, and I really ought to try to find another one at some point.
I 3Bonded one side of the gasket (the cases side) and fitted the ally seal mount.
Interestingly, the 3 holes are NOT in exactly 1/3rd circumference locations, the screws wouldn't screw down until I rotated the mount 1/3rd.  If I remember I may etch an "up" arrow into the ally just to make it easier next time.


Test-fitting of the timing wheel - as I was looking at the cases on the legs, and the wheel hanging on the wall I had a sudden panic that it wouldn't fit!!
But it does.


It's a nice tight fit on the output shaft splines.  I also like implementation of the fine-adjustment collar.


Woodruff key, splines, output cog and fixing nut, There's also a couple of large washers that fit over the nut which stop the cog sliding off.



I rummaged around in the box-o-bits but couldn't find another nut of the right size and thread to temporarily hold the splines on the shaft: this nut is the right size, but wrong thread, but it'll do for now just to stop the splines falling off.


I need to make up a pointer for the timing wheel: current thinking is to just use a bit of wire-coat-hanger and one of the mounting studs to hold it in place, can't see any problems with doing that, so will do that when I get to that point.

Next job will be the barrel studs (copa-slipped, and with a touch of grease on the rotating bits), barrel, with 3Bonded paper base gasket, quench the head gasket : Ooo - a heaty bit, watch out for fireworks!, and the head, rocker box, then timing gear..... should be fun!

[Rockburner]

Next stage.... the barrel.

These are the barrel studs.  The little discs above them go into the blind holes in the cases first to act as a "bump-stop" and (I think) to help against galvanic corrosion (or something)


Each one gets a small amount of copa-slip (One day that tub will run out, and I will be left hopelessly bereft!)


All in situ, and tightened down hard:


Cleaning up the excess copa-slip that was left


Ready for the piston: already have new rings and gudgeon pins.


The first bit is easy - piston and pin slid together nicely.


The circlips though were a bit of a fight to get in - but eventually I worked them in with a large pair of needle pliers (which is probably where that scratch on the piston came from. :roll: hey ho.


The second one was just as hard to get in.



Imprompto hook (from an old bungee net) bent up to keep the piston from flailing around.


Sika Wonder Wipes and meths again to get the base gasket surface clean


3Bond application, tried to put the minimum on this time, so just dabbed it on lightly and spread it out thin








The base gasket was fitted and more 3Bond lightly applied to the top surface of the gasket, then I checked the ring gaps: they just need to be "opposite" each other, and from memory, they shouldn't be directly on the "thrust" sides of the piston (ie, fore/aft), so I made sure they were lined up on each side of the piston:




Rather nice little ring-clamp from Dad's collection :


Much easier and lighter than some I've seen


And this is where I envy Zaphod Beeblebrox..... a 3rd hand would be helpful at this juncture.


GAH!  First attempt and the friggin bottom ring managed to slip out after the ring-clamp had slid away!


But, after a couple more attempts (it was a bit of a fight to get the rings into the bore!)
Yay!


Up


And down she goes!


The piston moves nice and freely in the bore, must remember to drip a little oil in there just to help it slide before I do the head gasket.
I pushed the barrel down and wiped up the worst of the 3Bond excess


Then stuck the head on so I could pull the barrel down tight and let the 3Bond go off properly in compression.
Here's the head sitting on the top of the studs so you can kinda see how the studs work.
The upper part of the stud assembly is free to rotate so it pulls the head down onto the barrel.  With studs like this, you can remove the entire barrel and rockerbox assembly without having to split it all up (should you want to)



However: doing up the studs is a long process because you can only rotate the stud with a spanner about 1/3 of a turn each iteration..... so I broke out my new secret weapons....


Wera Joker spanners: they're good.


You can flick the spanner back and forth like a ratchet spanner:   Took a few tries before I really got the hang of it, they do tend to drop away unless you use your other hand just to keep them aligned on the nut correctly, but by f~ck do they speed up something like this!  The studs go into the head by about an inch (approximately) on a relatively fine thread, so  it's a LOT of 1/3 turns to do - the Joker cut the time down I'd estimate by at a half, if not more.  I was pressed for time while I was doing this last bit as well, so I was very grateful for having the Jokers! (I can't seem to put an Amazon url into here - so just search for "Wera Joker Self-Setting Spanner"  I have a set of 4, each one covers a smallish range of sizes.)


I left the head tightened down so the 3Bond has time to go off and the base gasket should be all set by the next time I get into the workshop.



Coming up!

Fire! Heat! Water! Imminent probability RB burns himself!

[Rex]

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.

[Rockburner]

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.

It is yes, i had to look 3 times though...

[Rockburner]

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!)

[cardan]

Looking good. I notice there's not too many fins on that cylinder head. Was your dad running it on petrol?

Leon

[Rockburner]

Looking good. I notice there's not too many fins on that cylinder head. Was your dad running it on petrol?

Leon

Yes, the flywheels are 350, so the piston travel is only 80mm, compression is down to about 9:1 (ish), it was put together as a road bike, not a full blood race engine deliberately to make it easy to ride and to use petrol.

[Vreagh]

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

[Rockburner]

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

It could well do, but it's the head I've got and the other head i think has similar finning.

The engine ran well enough for  quite a few years in the past.

[Rockburner]

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!