Stu's Zephyr 750 C1 Restomisation Project

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Stu's Zephyr 750 C1 Restomisation Project

Postby Stu » 06 Sep 2017, 15:27

The story so far…

The project started in April 2016 when I bought a 1991 Zephyr 750 C1 from eBay. It was a scruffy going concern, legally on the road, and I picked it up and rode it home from Bristol to Chippenham, about 25 miles. Price paid was just £690. It was, as we Brits say, a complete shed. Power and brakes were close to non-existent, gear change stiff and nasty, handling dangerous. Even at that price it wasn’t good value. The good news was that it came with a late seventies single digit registration plate "FYC5T" valued at £600.

My intention was to patch it up a bit and ride it, see if I liked it, fix it if I did or break it for parts if I didn’t. Unfortunately there was simply too much wrong with it to get it into a safe, rideable state without doing everything. After some thoughts of selling or breaking it, I bit the bullet and climbed in…

It came with a very nasty Nexxus exhaust and a chrome carrier, neither of which were going to make the grade, so they both went back on eBay and netted me £90… with the plate valued at £600, I could convince myself I got the bike for nothing, which I suspect was roughly what it was worth. :?
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Stu » 06 Sep 2017, 15:37

I started stripping it properly in about August 2016, after I’d moved house and had my 1050 Triumph stolen.
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Stu » 06 Sep 2017, 15:39

It came apart fairly quickly apart from two seized components; the lower rear engine bolt and the swingarm spindle were seized pretty solid. After a month of soaking them in various penetrating solutions I gave up and gave it to a friend with a farm workshop who pressed them both out without much effort. :roll:
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Stu » 06 Sep 2017, 15:54

After that, getting a pile a parts clean enough to dump at the powder coaters wasn’t too difficult. Ten days later (and a large pile of cash) I walked away with lots of shiny bits. A couple of days fiddling saw a rolling chassis coming together.

Everything was done in gloss black except the fork sliders (satin) and the wheels (gunmetal grey).

Forks were rebuilt with new seals and stainless bits. The bike came with what seem to be “Progressive Suspension” dual-rate fork springs, so they’ve gone back in for now with some 15W oil.

Shocks were replaced with some “Protech” units built just up the road from my office. Same shocks as the “2win” units from Shock Factory.

Tyres are Bridgestone BT023… one of my favourites.

Discs are Tourmax, Japanese made, OE quality jobs. Calipers and master cylinders are ER-6 units all round. The rear took a bit of effort; it’s mounted on a ZZR600 bracket with a 240mm disc (standard is 230). Brake pipes are from Wezmoto and built to my measurements as standard ones don’t fit. Pads are EBC HH. It should stop!

Credit to Gazzz for the method of fitting the rear brake: http://www.gazzz-garage.com/2016/06/10/about-seven-fifty-cafe-zephyr-rear-brakes/
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Stu » 06 Sep 2017, 16:18

With the rolling chassis together, I ignored the big dirty ally lump sitting in the corner of the garage and started on the bodywork.

Everything had been painted in a thick gooey blue mess, so I stripped everything back to bare metal (tank) or original paintwork (plastics). Interestingly my side covers were candy blue and tank and seat unit were originally candy red. Front mudguard was damaged around the fixings so after an abortive attempt to fix it I bought a good used one from an eBayer in Austria.

The tank took a bit of effort. After derusting it with acid it started leaking through a couple of pinholes. I lined it with an ethanol proof epoxy. If I had to do it again I'd use Caswell!

All painted with aerosols for now, primer, base coat (Peugeot Aegean Blue) and a petrol-resistant lacquer. Badges are vinyl cut to my design and stripes were a few quid off ebay. All under the clearcoat. I may cough up for a pro paint job one day, but for now I'm pretty happy with the way it turned out.

After a couple of weeks hardening on the Mrs' dressing table (she was on holiday!) it's since spent 6 months in the lockup waiting for a bike to sit on. Should be hard by now!
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Stu » 07 Sep 2017, 10:07

With the bodywork done, I was forced to look at the motor. I’d set myself a pretty high standard with the chassis, so I’d been putting this off. There was no way I was going to be able to do this nicely without taking it completely apart and while I’m OK with top end rebuilds, bottom ends always give me the shits. Irrational fears… :roll:

I started off taking the top end apart. I already knew that it had been running with zero valve clearances, so the valves would probably need some attention. With only 27k miles on the clock I was expecting the bores would be OK, but I found one scored piston/bore and all the bores slightly out of tolerance (I think it’s had a hard life!).

I’m fortunate to have access to industrial cleaning machines (I work in the Rail industry) so the head and barrels were stripped and the castings aquablasted then cleaned out in an “industrial dishwasher” for half an hour. With the castings clean and dry, I gave them a coat of Autotek heat resistant paint in Aluminium finish. They looked pretty good.

Zephyr6.jpg


After ordering and receiving a set of IMD oversize pistons, the whole lot went off to my local motor engineer for reboring and valve recutting. They also had the cams and bearing caps, and sent the head back reassembled with clearances adjusted. I’m yet to check they got it right! They were clever enough not to mess up the new paint. Parts came back as clean as they left.
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Stu » 07 Sep 2017, 10:25

Deep breath, clean up the area a bit, and start on the bottom end.

Of course it’s never as difficult as you’ve been imagining; the Kawa motor is nice and simple compared to a bevel Ducati!

The main reason for doing the bottom end, if I’m honest, is to clean and repaint the cases. While the cases went through the same process as above, I decided while I was in there to replace all the wearing parts in the starter clutch. For £100 it seemed like good insurance against the inevitable failure later on. On inspection it was well worn, so worth doing.

There are two sets of rubber dampers in the drive line from crank to gearbox sprocket. One set in the secondary/starter clutch shaft which is reasonably easy to replace and another set in the clutch basket. More on the clutch later.

On receipt of yet another order of spares from Cradley I started the rebuild, which didn’t take too long and went together pretty smoothly.
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Stu » 07 Sep 2017, 10:42

One thing I haven’t mentioned is renovating of old and rusty steel parts. While I prefer where possible to replace fixings with stainless, with parts such as wheel and swingarm spindles, disc and engine bolts etc., this isn’t always possible or ideal. I’ve had a zinc plating kit on the shelf for a few years, but never found the time to use it. For this project I dug it out and have re-plated all fixings that I’ve reused. While the results are far from shiny, they’re clean and a nice matt silver which hopefully won’t corrode too fast. As I’ll get to later, I’m not really into shiny, so this suits me fine.

The process is time consuming, messy and fiddly, but worth it.
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Stu » 07 Sep 2017, 10:52

And that brings us pretty much up to the point where the old forum crashed. I’ve been a bit slack for a couple of months for various reasons, but am now back into the project with a vengeance. I had a week off work last week and started moving things along… there’s a way to go, but there’s light at the end of the tunnel. Bit soon to tell if it’s a train coming the other way.

On Freddy’s advice, I decided to put the bottom end of the motor into the frame and build the top end in situ. Once I’d buttoned up the bottom end (and left it to mature for several weeks in disinterest) I spun it over lowered the bike lift I’d built it on down to the right height, wheeled the rolling chassis across the end of it, and gently slid the motor into the frame. I used pipe insulation to protect the paintwork, but it was so easy I probably didn’t need it! Good advice, Freddy.
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Stu » 07 Sep 2017, 11:56

With the motor off the bench and in the frame, a quick clear up of the lift allowed the bike to be pushed back up and I could start work on the top end.
First to go on was the pistons, taking infinite care not to drop anything down into the cases or allow the circlips to turn into “pingf*ckits”.

I did have a moment; after turning the crank I realised I couldn’t turn it backwards to release the old socks I’d shoved under the pistons… bit of a fight with some long nosed pliers got them out!

Note the home-made ring compressors, made from cut up aerosol tops and cable ties. Another bit of advice from Lord Freddy that was invaluable.

Also fresh paint on cases and clean, zincy bolts. No, I haven't cleaned up the starter motor...
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