1979 KZ400 B Restoration/Recommission

Hello! In case you haven't seen my new members post, I'm Adam and this is my 1979 KZ400 B that I'm restoring.




As a brief bit of background, I'm in the UK, 30 (soon to be 31) years old and an engineer/project manager by trade, originally in Automotive, now in Rail. I spend most of my time messing about with older cars, repairing/modifying them, but have always been into bikes but only really got into riding and passing my full bike license about 3-4 years ago. I've had a very nice, low mileage Suzuki GSX600F which I've just recently sold, and at the tail end of 2021 I bought my KZ400.



The reasoning behind the KZ is that the Suzuki while very nice and reliable, didn't have anything to do on it, I like something I can tinker with and is a bit different. My grandad had a BSA Thunderbolt and a Honda 400/4 a few years ago and they left a bit of an impression on me, I wasn't particularly picky about the bike I wanted to have for a project, but it had to be at the right price (discounted most BSAs these days) and ideally a twin (discounted the Honda).

The KZ turned up at an importer near me, went to have a look and ended up buying it, it's a California import and had been off the road for around 25 years or so, appeared to be mostly complete but as I've gone through it, I've found a lot needs replacing and some fairly key items are missing or are no good.

I have been posting about the build on another forum, but I'll try not to copy/paste too much. So getting stuck into the bike, clearly some bits had suffered from being sat outside

The seat base was totally rotten, and the brake master was not only stuck solid but the reservoir had gone brittle and holed





The sun bleaching on the tail piece was pretty impressive!



I had been sold the bike as having a seized engine, so one of my first jobs was to see if that was actually the case, I got the spark plugs out and put a good spray of penetrant and ATF into each cylinder



Left overnight, tried a long spanner to turn it over the next day and it was free! Didn't seem to be particularly badly stuck at all. My plan was to completely strip the bike down and start from scratch, restoring little sections at a time.

The main frame of the bike was in good condition, but pretty much anything rubber or plastic was quite badly affected by the sun, these carb mounting rubbers in particular were rock solid and very cracked



You can also see (or rather not see) that a starter motor is one of the parts the bike was missing. Speaking of carb rubbers, the carbs themselves were not in great shape, I left these for a while and look into them in more depth later.



But as you can see, they're not pretty! By the end of January the strip down was pretty much complete






My plan from here was to tackle the frame and associated parts first so I could get back to having a rolling frame, then look at the engine. I'll continue that in my next post as it's gone midnight here!

Looking like you have made progress.  I also see the MG Bgt in the shed. I would say you have several things to keep you off the streets and out of bars/pubs.

Oh yes I've got plenty to keep me out of mischief! The MGB GT was/is my first car, bought in 2012, used daily until it came off the road in 2015 and been a slow project ever since haha, the bodywork is the main thing that's slowed me down there, here's some photos of it in happier times

My strengths are definitely more on the mechanical side of things which is probably why the bike has been progressing quite nicely in comparison!

At this point, it's probably worth me saying that I'm not going for a perfect concours type restoration on the KZ, while I'm not being overly budget about it either, I'm trying to repair and re-use original parts where possible to give me a nice daily rider that also has a classic look about it.

The last bit that really fought me on the frame was getting the centre stand pivot out, it was pretty rusted in there by the time penetrant spray, heat and hammering had got it out! It certainly went back in with plenty of grease after I gave it a good clean up.

First step to getting back to a rolling frame was to give the forks an overhaul. First time I've ever done this but it was fairly straightforward, the main pain being trying to get the damn snap ring at the top of the forks out and then back in again while depressing the centre cap!

The forks weren't in too bad condition, a bit of pitting on the stanchions but light enough to be lightly sanded off, bit more rust up where the headlight mounts would go, which I did sand off, and is nicely hidden by the aforementioned mounts.





The old oil was very old as you can imagine, gave the forks a very good clean out, springs were still in spec so kept those but rebuild up with new oil and seals. This was happening in February so was taking some smaller bits into the house to work on in the evenings.



The tailight unit was a pretty simple job of taking it all apart, cleaning out years of California dust, a good going over with some satin black, some new light seals and put it back together, the wiring was in good condition considering, in fact probably 99% of the wiring on the bike is in pretty good condition! The battery box is just about usable still and I got a new clutch lever as the old one was missing it's end.

I had a little paint set up for some of the small brackets and bits



Foot pegs were in a pretty usable condition still, and the side stand and it's curious auto-retract system all looked to be in place, although it only had one spring rather than the two I believe it should have. Of course there was one slightly larger item that needed some paint as well





The frame really looked to be in good condition, a little surface rust here and there, and some of the open tube ends had been filled with years of dust that got washed out. I gave the whole thing a sand, put some rust converter on the worst bits and then gave it a good few brushed coats of gloss black.

 

Right I'd better keep working on getting this up to date!

Next my attention turned to the wheels. The tyres were ancient and needed to go and the wheels themselves had rusty spokes and while the rims aren't perfect, they're usable. Keeping with the ethos of reusing parts if they can be and not just changing things out for the sake of it.

The tyres put up a bit of a fight as they were old and rock solid, but got them off eventually



Ended up cutting most of the spokes out, but got a few out whole for length references etc. Knocked out the old wheel bearings and gave the hubs a good clean up and light polish



Amusingly the linings just fell off the brake shoes once I got them out haha, just another thing to add to the shopping list



It's quite satisfying even just cleaning up the little bits like the speedo gear from the front wheel, this was full of ancient grease and dirt, but after a good wash out with thinners, a little polish up and a new seal it was greatly improved





Likewise, the wheel rims themselves, although not perfect, really came up nicely after a good clean and a go over with some polish, certainly good enough for my needs anyway!

The front brake disc was still well within wear limits so I gave it a clean up and painted the centre and it came up great, the slight overspray from masking will either be dealt with by the pads, or I'll nip it off with a bit of sandpaper later



Built up the rear hub (and front hub) with all new bearings, new cush drive rubbers and seals. Gave the outer housing a bit of a sand and polish but didn't go crazy with it



By this point, my stainless steel spokes had arrived and I had my first go at lacing wheels! Helped along greatly by reference photos I'd taken of the wheels before I stripped them, and various videos on Youtube etc.





I did also get myself a truing stand and had a go at getting the wheels pretty well trued up, took a bit of learning but got them pretty good in the end. Ordered some new inner tubes and some Dunlop K82 tyres to get that classic look and set about fitting them and that was the wheels about done

I'm trying to keep these in somewhat chronological order haha!

The fork clamps cleaned up quite nicely from what I started with







The rubbers for the handlebar mounts were a bit of a pain to find, but managed to get some. Just some of the parts availability issues that seem to plague these 400s! I had a bit of a nightmare with the head bearings when I got sent the wrong set and didn't realise until I'd put the upper race in! But I managed to get it back out and the company sent the proper bearings. I've converted to taper bearings from the original ball bearings.

What I didn't realise at the time is that these seem to sit a bit higher, and now that I've got the headlight brackets on, I need to get a thin spacer to stop them rattling about as the fork clamps sit ever so slightly further apart than previously.

Around that time, while the evenings were still cold and long, I started looking at the switchgear that came on the bike. The outer housings had suffered from sun fading, and some of the plastic internal parts of the switches had crumbled to nothing also, this was the kill switch



The Hi Lo headlight switch had snapped off, a common issue it seems since you can buy repair kits for these from Z Power. I ended up buying a second hand right hand switch assembly from a less sun damaged UK Z400 and made a good one out of the two. With a bit of sanding, satin black paint and some paint pen work, the switches almost look good as new. Saved a little bit over buying new and haven't wasted perfectly serviceable switches.

Nice job so far!  Interesting reading.  I've got an old 1972 cb350 that I need to go through like this, but not sure if I have your patience.  Those rims really turned out nice!

Got a lucky score on ebay, a new (to me) seat to replace the absolute shambles of a seat that came with the bike! A slight tear on the cover of the new one but I'll probably put a little tape over it just to get the bike on the road, then set about faffing with a new cover later on.



At this time I was also rebuilding the aforementioned forks, after working out how to get those pesky top circlips out!



Had an initial look at the last bits of wiring I took off the bike, it actually looked worse than it was, the main bit someone seems to have messed with was cutting the wires to the ignition switch for some reason



I also started looking at the front brake caliper, this proved to be a major pain and took quite a while to sort out



This particular type of caliper seemed to only be used on some of the late 400s and maybe some of the 440s? So parts were a challenge to find, and even just getting the thing apart was hard enough!

Had a fitment issue with some replacement brake shoes bought, the diameter wasn't right for the pivot



Sorted by getting some genuine Kawasaki shoes instead

Thanks! I had hoped to get it on the road for the summer, missed that target but I'm just happy plodding along with it, hopefully should have it done by Spring now ready for the good riding weather

Swing arm all painted up after a lot of time spent cleaning out all the old grease



And just in time for some new YSS shocks to arrive!



The old shocks were too far gone to do anything with unfortunately, fair bit of corrosion on the damper rods and they were likely all shot inside anyway. I did have to swap the crush tubes from the lower bushes though as the ones on the new shocks were the wrong diameter but easily swapped and got them on the frame along with the swingarm, starts looking like a bit like a bike again haha



Started getting a bit of momentum around this time (June '22) forks got finished and fitted to the bike along with the mudguard which had a bit of cleaning up, nothing too major on that really.



Even went so far as to put the wheel on as well



Make that two