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Brake caliper. Got the piston out using the grease gun method as I don't have compressed air



Just needed a clean up and was serviceable thankfully. The pivot that the caliper moves on was the real challenge, it was stuck in place. Tried penetrant sprays, heat, hammering and eventually got it out after a few bakes in the oven and the use of a press





One of the (NLA) pivot seals was completely toast but managed to find a replacement, also managed to find a set of piston seals quite cheaply also. The pivot itself had a small bit of damage on the end where a misplaced hammer blow had slightly closed up the gap where the retaining circlip goes, so a bit of careful filing opened that back out. A spot of rust removal, paint and new pads and it was all ready to go back together





Also on the front brakes I'd bought a whole new master cylinder and cleaned out the block that houses the brake light switch, I did order brake lines a couple of times but both times they ended up being wrong! So I'm now tempted to either find a company local, or someone I can send my old lines off to so they can make exact replicas and I know they'll fit.

Next job was to clean up/restore the gauges

The gauges didn't actually seem in too bad a condition overall really. Just the usual mix of dirt and sun damage. As you can see below, the seals that the gauges mount onto were totally shot though, and of course, are NLA



The brackets and rear halves were easy enough to sand down and spruce up with a bit of satin black, eventually I'd like to find some way of making a decal to replicate the original tell tale light labels, just need someone with the skills and a good reference pic to work from





For the seals, I bought some large O Rings, which are the perfect size and seem to do the job!







With the casings of the gauges painted up, they look the part now. I didn't actually fully strip them down as I figured I might cause more harm than good. Once the bike is working I'll see if either gauge works and can rectify then if there is an issue.

Next up, as I couldn't really put it off any longer, I started to investigate the engine..

Looking great and thanks for sharing!  Love the photos!

Congratulations on a fine rebuild of a classic bike!  You've done a lot of nice work in a short period of time.  

Thanks guys I've been pretty happy with how it's been going so far, considering how I went into it with not much experience at all on old bikes, I think it certainly could have gone worse than it has so far!

So the engine, to recap, I was told it was seized when I bought the bike, but an overnight soak with ATF down the bores got it turning, so I don't think it was badly seized, maybe just a bit stuck from years of sitting and old oil etc.



It did have some bits missing, the points/condensor and points cover are gone, perhaps someone was investigating a non running issue before it was parked up. Also the starter motor and cover were missing although the starter chain and the sprocket from the motor were there. The banjo bolt for the oil line to the head and the oil pressure switch were also missing and the hole was caked up with dirt so clearly this had been off and the bike hadn't run in a long time.

I decided the whole thing needed to come apart to see what I was dealing with, so started from the top and worked my way down. This is the third engine I've fully stripped after the B series from my MGB and a BMW straight 6 engine that at one point I was going to swap into the B but never did..

Rocker cover came off and initially looked pretty clean, but then it would, it's at the top of the engine!



Some marks on one of the rockers aroused a bit of suspicion



With the bike sitting for so long, I was really on the lookout for internal corrosion more than anything, so was initially fairly happy with the looks of things



But a closer look revealed all was not well...





One rather ruined cam bearing and the cam lobes weren't looking too clever either!

Decided to carry on anyway, the pistons looked ok, they were covered in a load of debris but it came off easily enough. The bike had an exhaust, spark plugs and carbs fitted when I bought it so must be just general muck from combustion, but still seemed a bit excessive





Bit of a telltale mark in the bores were the pistons and rings had been sat but no heavy wear ridges or anything so good news in that regard, still on standard bore sizes so doesn't look like it's been too messed around with in the past.



With the head and barrels off, turned attention to the side covers. As mentioned before, the points cover was missing, and judging by the condition of the ATU behind the plate, it had been missing for a long time! Rusted solid but was able to get it off the crank at least





With the primary chain cover off, the first signs of what may have caused the cam bearing issue became clear..



A lot of sludge! There would be more to find later on but who knows when this thing last had an oil change when it was actually a running bike! The clutch plates were pretty stuck to each other as you'd imagine and there was a fair bit of surface rusting on the plates so I'll probably change the lot to save chasing annoying clutch issues in the future, the oil pump looks like it might have some light scoring marks on it, but I've not investigated this closely yet to see if it will go again

I did also remove the alternator casing and found mostly the same, old oil etc. then it was time to split the crankcases with only a minor spill of oil that hadn't already been drained!



Now considering the state of the sludge and that cam bearing, I was pretty amazed at how good the bottom end was, a bit of wear showing on the bearings but the crank is in great condition





I will try and get some replacement bearings since I've got it this stripped down anyway, once I've identified which size bearings I've got and what I need to order. The lower crankcase was less pretty





It was very satisfying cleaning it all out though! I think the gauze filter had been neglected for a long time, as it was nearly completely blocked with sludge, I think this defintely caused the oil starvation issue that ran the bearing in the head.



After a session with TFR and a jet wash

Just about up to the present day now so I can stop spamming the updates!

I think I mentioned previously that the carbs weren't in a great way, I did take them off and had an initial look, I then put them to one side while I focused on the frame etc. When it came time to look at them again, they were worse than I'd remembered





I knew one of them had a torn diaphragm which seem to be eye wateringly expensive, so I was already torn (ha) about what to do with the carbs, but one of them looks like it's been sat full of water for a couple decades. The corrosion has eaten away much of the aluminium in the bowl and that carb is scrap. I then made the other carb scrap as one of the posts that holds the pivot for the float snapped off while I was trying to drift out the pivot pin.

Not a huge loss though really. I then did a bit of reading and thinking about what to do to resolve this. There were a set of replacement diaphragm type carbs on ebay for quite a bit of money, and some of the earlier type piston carbs as well, but then I got reading about Mikunis and a couple of places offer "conversion kits", the more I read, the more it seemed like a decent idea (including reading a post on here about a KZ400 with some Mikunis on).

Rather than pay the amount for a kit, I happened upon a pair of very reasonably priced 28mm Mikunis locally, so picked them up.





I'd partially stripped one to have a nose inside but they're totally complete and just want a bit of a clean really. They're a matched pair so the Choke lever will come out the side and be easily accessible, obviously they'll need jetting from whatever they were on before but I can deal with that nearer the time. I did buy some new mounting rubbers for the CV carbs before I realised they were fubar'd and the diameter is a bit bigger than the Mikuni's so I'll need to work out mountings later also.

I'll run them with K&N pod filters as although I was all ready to run the factory air box, I really don't like how big and bulky it is so I'm glad that will be going.

Aside from that, I've been mocking bits up on the bike again, just to free up storage space more than anything! Also cleaned the wiring loom and all the connectors and have started laying that in place





In the last week or so, I've been trying to make all the locks work. I had a new key cut as it didn't come with one. The fuel cap got working with a lot of WD-40 applied, similarly with the ignition switch but the helmet lock needs a little more work to make it happy.

The cylinders have had a hone and have cleaned up really well, and I've managed to score a second hand cylinder head for a good price, it's missing a couple valves, but I'll be able to make one good head out of the two. I'll also get all the engine casings vapour blasted before building it up again, saves me sitting there for hours with a wire brush!

Welcome to KZR , great progress being made and nice documentation/write-up.

This is a really fantastic writeup! Great pictures! That sludge, though...

For the wheels - did you add rim strips before installing the tubes and tires? The strips protect the tubes from the spoke fasteners.

For the seat - rather than tape, I'd like to suggest the following. Find a decent section on the old seat - might be a little difficult - and cut a piece of the cover that is 1"-1.5" larger than the split in the good seat. Carefully push the recovered (ha!) piece through the hole in the good seat so it is centered under the split. Use the strongest adhesive you can find to glue the underside of the good seat cover to the surface of the patch; this includes gluing down both edges of the split. Don't worry about getting the edges of the split to touch: once everything is secured there will be no padding visible and if the edges are slightly apart there will be less tension on the patch.

Excellent work - wishing you continued good luck on the project!

Galfer, USA can make you custom brake lines.  They have really good quality.

This is some really nice work so far, good job