Stu's Zephyr 750 C1 Restomisation Project

Document your ongoing rebuilds and restorations here
David Richard
Posts: 273
Joined: 04 Sep 2017, 20:21

Re: Stu's Zephyr 750 C1 Restomisation Project

Post by David Richard »

hi stu thats rewarding after all the hours you have done dont get it dirty now ,do you know what size the sprockets are on it ,david
User avatar
Stu
Posts: 123
Joined: 04 Sep 2017, 10:12

Re: Stu's Zephyr 750 C1 Restomisation Project

Post by Stu »

Hi David. I guess 15/38, I bought a standard set off Ebay about 2 years ago. From today's brief ride I'd guess it could happily pull another tooth on the front.

16 front from Wemoto is only 8 quid...

Sort the clutch first... and find another baffle for the exhaust... :shock:
David Richard
Posts: 273
Joined: 04 Sep 2017, 20:21

Re: Stu's Zephyr 750 C1 Restomisation Project

Post by David Richard »

hi stu yes very true i went up to 16 then 17 it suits the motor 6 k is 82 mph ,i have the old 16 teeth one pm me your address ill send it up to you its done about 100 miles i wont ever use it ,david
User avatar
Stu
Posts: 123
Joined: 04 Sep 2017, 10:12

Re: Stu's Zephyr 750 C1 Restomisation Project

Post by Stu »

Thanks very much, I'll take you up on that. I had a Bandit 600 for a short while and went from 15 to 16 to 17 on that. Had to file the cover away inside for chain clearance, but so much nicer afterwards.

Had the clutch apart twice this afternoon, measured and inspected everything and finally concluded there's nothing wrong with it. Put it together with just two springs and it still felt horrible at the lever, even though I could work it at the cover with my fingers. Took the brand new "pre-lubricated" cable off and stuck some proper oil down it... it's much better now! Reassembled, and it's still heavier than expected (maybe it has beefed up springs in? - they're stock length) but at least it's smooth and consistent. Fiddled with cable routing for ten minutes or so and couldn't find an option better than I'd done it originally so left it as was. I can live with it; still lighter than my old Ducati just not what I'd expect on a UJM.

Replaced the rusty indicators with new ones... no difference whatsoever, still flashing the tail light. Better earthing all round coming soon.

Took the supplied baffle out of the exhaust... it's useless... a bit of perforated pipe achieving nothing as it has a fat annular hole round the outside of it. Measured the hole it came out of and ordered a 48mm replacement from ebay (as suggested by NL Richard, ex of this Parish). Should shut it up a bit! Still need to move it over a bit to clear the swingarm... I tucked it in as tight as possible and am reluctant to move it too far out from where it is now.
David Richard
Posts: 273
Joined: 04 Sep 2017, 20:21

Re: Stu's Zephyr 750 C1 Restomisation Project

Post by David Richard »

Hi stu thanks i got you message ,but a server error stopped me replying through that means dont worry about post its a jtf i will post through the week good news on the clutch ,david
Freddy
Posts: 695
Joined: 06 Sep 2017, 11:06
Location: Sydney Australia

Re: Stu's Zephyr 750 C1 Restomisation Project

Post by Freddy »

Stock, and everything working correctly, the clutch effort should be what you'd call a 'light action'.

As it wouldn't be uncommon for someone to experience clutch slip, the reason they ungraded the clutch from the C5 model onward (and even then the upgraded clutch needs heavier aftermarket springs to not slip if you use synthetic oil and accelerating hard in the upper rev range) it wouldn't be unreasonable to assume someone may have fitted heavier aftermarket springs.

I use heavier clutch springs in my D1 and I don't think the length is much if any different. It is a heavier wire gauge that makes the difference. With these springs I'd describe the action as 'moderate'. I only noticed the difference at first, now I don't even think about it. Certainly not uncomfortably 'heavy'.

A slight aside, whenever I've experienced clutch slippage and pulled it apart there has been very little wear on the plates. It has always been a loss of spring tension that has been the problem. It's even been necessary to replace the heavier gauge aftermarket springs after some period.

P.S. The only other thing I can think of is probably pretty obvious, the clutch pull rod and its attached arm are close to 90 degrees to the cable pull direction when correctly adjusted? There is a mark on both the rod and arm that should align.
User avatar
Stu
Posts: 123
Joined: 04 Sep 2017, 10:12

Re: Stu's Zephyr 750 C1 Restomisation Project

Post by Stu »

Thanks, Freddy.

One thing I remembered last night was that, when I took it all apart, the clutch cover gasket face was smothered in blobs of blue sealant so some wrenchmonkey had been in there. All bets are off as to what said monkey did, but from the quality of his work I can only assume he was working on the cheap. The old owner lived about five minutes walk from one of the biggest motorcycle spares stockists in UK, so I doubt new gaskets were unavailable. Clutch plates all look new/excellent, but the springs could come from a Harley for all I know. Anyway, it seems OK at the moment so I'll wait till I've ridden it again before I try anything else. It may be that Mr Blu-goo bought a set of EBC 117 heavy duty springs at your recommendation!
IMG_20170414_121828.jpg
:o :o :o :o :o

Marks on actuating arm are correctly aligned. ;)
David Richard
Posts: 273
Joined: 04 Sep 2017, 20:21

Re: Stu's Zephyr 750 C1 Restomisation Project

Post by David Richard »

hi stu its on its way ,parcil force ,david
User avatar
Stu
Posts: 123
Joined: 04 Sep 2017, 10:12

Re: Stu's Zephyr 750 C1 Restomisation Project

Post by Stu »

Cheers, David. I owe you a pint!

Got her all reassembled tonight. Reangled silencer bracket and found a couple of mm clearance. Clutch is miles better.

Will change sprocket and baffle in exhaust later in the week and she'll be ready for another quick run.
User avatar
Stu
Posts: 123
Joined: 04 Sep 2017, 10:12

Re: Stu's Zephyr 750 C1 Restomisation Project

Post by Stu »

Got a few bits through the post and played for half an hour fitting them. New baffle for the pipe, a couple of replacement screws and a new sprocket. The 15 was so low, I decided to put the 16 on the shelf (sorry, David) and go straight to a 17. Fitted them all in half an hour and off out for a quick spin on the private roads round the estate (ahem).

A hundred times better than it was last week... clutch is easy and gearbox snicky, motor pulls smoothly (up to a self imposed 5000 rpm on the new pistons) and the bike seems to handle nicely and copes with slow speed work and up to 60 on the straight. Even slipped in a couple of overtakes! Did just over 5 miles before arriving back home. Gearing is now much more sensible; it's doing 60mph at 4000rpm according to the clocks; I think I can live with that. Exhaust is still a bit loud but more bearable and getting there. I may try adding some wadding round the new baffle.

Two minor issues that will need further investigation: I noticed a single drop of engine oil drop under the bike when I parked it, coming from gearbox sprocket area. All new seals in there, so it really shouldn't be leaking. :?

And, when I stopped, the clutch sounded a bit like an old Ducati dry clutch, rattling when the lever is out in neutral, quietening when you pull the lever. :shock: Not quite as bad as a Ducati, but louder than any Japanese clutch I've heard before. Could be the screws coming loose that I put in to replace the rivets in the basket? I'll pull it all out and investigate before it falls apart. ;)

Really, really happy though. This one's going to be fun. :mrgreen:

Next step will be to get it legal... MoT test. I may leave it until the spring.
Last edited by Stu on 07 Dec 2019, 20:08, edited 1 time in total.
Post Reply