750 K2 Strip & Rebuild - help please

[K2-K6]

On balance I'd agree with further inspection to asses where it's at.

Is the outside non adhesive "self almagamating" tape on these? Common on looms generally and doesn't make all the contents sticky.

[Lobo]

Thanks Nige, for some reason I never thought of using self amalgamating tape. (loom using conventional electrical tape - ugh)

But, the good news is the loom’s been nicely put together with quality crimps and insulation - so my plan is to not bother stripping back further. Phew.

[K2-K6]

Good news if it's all good Simon, certainly makes it easier than diagnosis in situ after a reassemble 

As part of apprentice training we had six months in electronic section and making looms etc to aircraft standard complete with design protocols that would allow at least two repair when installed with designed in loops etc along with precise cable tying in old style.

Soldering exercise, they had us make a cube of rigid wire panels all soldered by hand to make the matrix and inspected for solder flow, fillet geometry etc. Then as final test the instructor placed the cube on the floor and stood on it (all sixteen stone of him ) a ritual cruel exposure in front of the training group, with mine one of three to survive the stress test. Still smug now 

[Lobo]

Pity you don’t live next door Nige; I’m sure I could find you plenty of work… later this year plan to rewire the Kombi with all the horrors that go along with that. (still undecided whether to modify the connectors / fuse box / terminals etc.).
With your amalgamation tape idea have now fully striped the K2 loom, washed it again, and will resheath it this week.

[Lobo]

An interesting last Friday with Lindsay, who is rebuilding my K2 engine.

The first job was new cushs into the Primary drive sprocket component, which had to be disassembled due riveted. Within there are 12 cylindrical rubber cushs; at 50yo they were rock hard and if deformed slightly  (using a pliers) simply split and stayed that way. We stuck ‘em in a bag, and when I put it down on the bench there was a solid clunk like it was a bag of marbles.

Initially 2x new needle roller bearings were pressed into the shaft. Next the 12 new cushs went in to the lower sprocket, with upper sprocket then pushed in place. (needed a press to coax this - very tight). Then finally 6 new Allen screws, into the holes pre tapped and countersunk, using thread locker of course. All now good as new.

[Lobo]

More progress on the engine rebuild…

The cases blasted, and despite being told 99% of the beads cleaned away, an amazing amount still came out. We thoroughly washed, (air line) blew all casings, dried them in an oven, and repeated the whole process. Fingers crossed, it really is aggressive stuff.

Next sprayed the cases with a HT Silver, before baking at 180C for an hour. Then the rebuild, which went quickly and with little fuss. I’d cleaned all parts thoroughly, and supplied all new bearings, seals, chains…. and re-zinc plated all fasteners. All gear dogs + mating faces undercut on both drive and overrun sides.

Head away this morn for valve work, barrels being rebored 0.5mm os.

[McCabe-Thiele (Ted)]

All looking good but can't see any assembly lube or is it colourless?

[Lobo]

Yup, graphite oil on big ends and mains, otherwise squirts of oil in all bearings / moving bits as we progressed. I’ll agree; it looks drier than it is…

[K2-K6]

The best bit, building them again after detailed preparation.

Always amazed at just how much research and development went into these engine, such nice details within those cases 

[Lobo]

It really is a thing of beauty, and fiendishly compact. Cable oiler very cunning; though will be ‘turned off’.

[Lobo]

Have some surplus VHT Silver paint, originally destined for the CB750 rebuild but not used. It boasts 1000+ C, and mentions exhaust systems etc. Q. How would it perform on non-hot components - specifically the carb on the old Kombi; which is out & in bits, so might as well get a bit of love…

[smoothoperator]

The VHT paint seems pretty tough stuff to me, but that is after curing in the oven. So if you are confident to put whatever part in the oven for an hour or so, I would say it would be worth a shot, even if that part never saw 150 C again. Maybe it would be a bit soft if it wasn't cured, and obviously you are looking for petrol resistance if you are painting a carb.

[K2-K6]

Have some surplus VHT Silver paint, originally destined for the CB750 rebuild but not used. It boasts 1000+ C, and mentions exhaust systems etc. Q. How would it perform on non-hot components - specifically the carb on the old Kombi; which is out & in bits, so might as well get a bit of love…

Unsure of predicting an outcome because of zinc-ee base material. Painted carburettor are few and far between and maybe because of this element, unable to competently adhere to zinc prominent metals.  It's decomposition being a protective strategy with micro surface conversion to zinc oxide (I believe) giving this characteristic, a little like self anodizing in effect.

Doubt if it will cause any difficulty, but may not be longer term permanent because of above reason. The paint should survive but may not be attached sufficiently to the casting to avoid bits falling away.

For zinc surface consider it like painting/priming galvanised items, so maybe a competent base layer would assist here.

[Oddjob]

I've never had a problem getting paint to stick to carb bodies Nigel, the linkages though are another problem.

My current 500 restoration features sprayed carb bodies with petrol resistant lacquer on the spray paint.

[Lobo]

Kombi carb body painted and baked @ 200C / 1 hr. Other bits plated. Annoyed at myself for not dressing the screws < plating; will do better next time 🙁

Thanks for the helpful comments…