Stu's Zephyr 750 C1 Restomisation Project

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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Freddy » 10 Sep 2017, 00:16

Stu wrote:With the head bolts in, I could put the cams in. The timing marks are a bit iffy; the exhaust cam mark is either a bit above or a bit below level with the head, and where the Haynes diagram clearly shows one pin above and one below the mark, mine line up perfectly. Much messing to get it in the right place, but I'm convinced it's now right.


Mine don't line up perfectly like in the workshop manual either. As long as the exhaust is in the tooth that makes it the closest, and the pin count to the inlet cam is correct, nothing else you can do. I think some of the alignment of the intake is due to not having the valve cover on. The top chain run does change as it deflects around the guide in the valve cover.

I've never been able to find a cam specification for the OEM cams to check the timing with a degree wheel (well not one I'd fully trust).
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Richard » 10 Sep 2017, 01:24

Same here although I did find it became better after turning the engine over some 10 times manually and then pressing in the chain from above. Obviously with the chain tensioner installed (as I found out the hard way... ;) ). It seems everything has to settle a bit after installing?
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Stu » 10 Sep 2017, 08:53

The instructions are clear enough until you try to use them! The manual shows the Z7EX mark level with pin 0 below it and 1 above, but the mark points directly at a pin! If I count this as pin 1, then with the chain tight I can't get the required pin count to the mark on the inlet cam unless the Z7EX mark is pointing up. If I count it as pin 0 (closer to the way it looks in the diagram) then with tight chain the z7ex mark points slightly down. I assume this is correct as the chain will dip slightly in the centre with the cover on.

This pic was taken during process, I think my final version! 47 pins visible, 0 to 46, Right to Left.
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Freddy » 10 Sep 2017, 12:28

Stu wrote:The instructions are clear enough until you try to use them! The manual shows the Z7EX mark level with pin 0 below it and 1 above, but the mark points directly at a pin! If I count this as pin 1, then with the chain tight I can't get the required pin count to the mark on the inlet cam unless the Z7EX mark is pointing up. If I count it as pin 0 (closer to the way it looks in the diagram) then with tight chain the z7ex mark points slightly down. I assume this is correct as the chain will dip slightly in the centre with the cover on.

This pic was taken during process, I think my final version! 47 pins visible, 0 to 46, Right to Left.


I can't really make out anything from the picture, but this is what to do to check the cam chain timing (based upon what the genuine factory manual says, plus the practical installation problem i.e. getting the front chain run tight enough). .....

Rotate the engine with camshafts installed around to arrive at the TDC mark. It's the only way to pull the front chain right tight enough. If you just try and pull it tight by hand as the manual says, guarantee you'll be a full tooth out after you've rotated the engine and really pulled the chain tight. Ask me how I know.

The Z7EX timing mark on the exhaust camshaft sprocket should now approximately align with the cylinder head upper surface. It doesn't exactly, its in the right tooth to chain location if moving it would make it worse. The chain pin the Z7EX mark points to is pin 0. Count 45 pins starting from pin 0, and the IN mark on the inlet camshaft should be sitting between the 45th and 46th pins. Don't worry that the IN mark doesn't align perfectly with the cylinder head surface. It's now correct.

With a truly tight chain, the Z7EX in the position that places it as near to the head surface, and the IN mark between the 45th and 46th chain pins ..... It's correct! Well as correct as you're ever going to get without using a degree wheel.
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Stu » 10 Sep 2017, 13:39

That's exactly what I did... took three goes to get it there. I wasn't 100% happy with any of them but it was the best of the three. Good to have confirmation, thanks!

Incidentally, with a new chain and tensioner blades I managed to turn the motor several times without the chain slipping. Try as I might I couldn't get it to jump the cam sprocket and had to take the cam out to move it a tooth.
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Richard » 10 Sep 2017, 14:55

Looks like you two agree so should be fine ;)

In my case, I placed 2 marker lines on both sprockets and the chain before I went any further, while reinstalling I made sure those markers were on the same spot, never counted pins (should have though) ;)

Then I stupidly made the mistake turning over the crank manually but without chain tensioner installed so the chain jumped one or two teeth. :oops: Next I couldn't get the markers aligned anymore so had to count pins after all and went through what you guys experienced as well, not perfectly aligned compared to the manual but nearly so I more or less accepted the difference as I couldn't get it any better...
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby vambo » 14 Sep 2017, 11:47

Impressive work..... 8-)

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hear me now, believe me later......
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Nelbert » 17 Oct 2017, 11:23

Morning Stu,Reading your restoration project with great interest ,a better job than I am attempting,however a question. How do you change the damping rubbers in the clutch basket? My basket has sustained damage in the past I have bought a used part with quite a bit of free play.Any tips would be very much appreciated yours Neil
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Richard » 17 Oct 2017, 21:42

This post shows the procedure
Now all you need is source those rubbers, I think there was someone in the US and someone in the UK imported a few as well. Sorry couldn't find more details about them.
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Re: Stu's Zephyr 750 C1 Restomisation Project

Postby Freddy » 18 Oct 2017, 01:35

Richard wrote:This post shows the procedure
Now all you need is source those rubbers, I think there was someone in the US and someone in the UK imported a few as well. Sorry couldn't find more details about them.


Email address of the guy in the US that sells them ...... turbosteve84@verizon.net
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