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Greetings, this is a further update on my progress thus far…
You may recall from my last post, I was having an issue with an unidentified, intermittent engine noise that seemed to be vaguely emanating from inside the motor.
After disproving a number of different theories on what this might be, I was left scratching my head…
In the meanwhile, there were inconsistencies with the manual cam chain adjustment and I also noticed a barely visible green stain in the shape of a couple of drops on the outside of cylinder #1.
So… the head had to come off and once removed, I was able to confirm that the head gasket was leaking and that the lower rubber cam chain idler wheel was partially shredded (another possible candidate for the intermittent, abnormal engine noise, I thought).
It looked to me like the PO had previously fitted an accessory brand head gasket (without the sealant rings) and it didn’t look like he used sealant around the water jacket ports or (anywhere else).


I gave the head the old “fill the ports to the brim with petrol” leak test – there was not the slightest leakage past the valves which was a surprise, I decided not to remove / disturb them.
I did not remove the block either, the cylinders are on standard bore and looked ok.
I had checked the cylinder compression (hot) earlier and the results were all within the manual service limit spec.
I cleaned up the top of the pistons and the combustion area in the head with some kero and a rag and was surprised how easily they cleaned up – I’m guessing that the only miles this head has done since being refurbed are the ones I have put on it whilst I have been out riding the back streets (initially struggling with carburation and other issue’s).
I installed the head using a new OEM gasket, I was unsure, but in the end, I used a little additional sealant on both sides of the gasket.
The bike started up without any drama’s (as per normal) and just as I put my helmet on, ready to head out for a test run, the dreaded engine noise was suddenly back – WTF!
By chance I happened to discover that the sound was coming from the tacho unit, when I disconnected the cable, the sound abruptly stopped.
Upon disassembly and inspection of the Tacho, the spinning discs that hold the magnet was partially seized and hard to turn by hand.
I was able to free this up using some fine lubricant and that seems to be the end of it…

Now, I was also able to easily adjust the tension on the manual cam chain adjuster, screw in until light contact, then back off a quarter turn…
I know… people tell me that the proper way is to adjust them is with the motor running, I did try it but could not find any sweet spot – it all seemed the same to me.
It got me thinking though, is my cam chain adjustment right?
As an exercise, I removed the cam cover and measured the chain slack between the cams, up and down I got about 8-9mm (seemed a lot).
OK, so I dug out an old OEM auto tensioner (the type that fail), checked that the spring was within spec (min, 71mm long), installed it, released the mechanism, turned the motor over several times slowly and then made the same measurement – I was surprised that it was very similar.
With an addition of a longer 6mm bolt and lock nut, the OEM tensioner can be made into a manual locking type of adjuster with the advantage that (periodically), when you release the lock nut and bolt, you get the factory chain slack adjustment (no chance of premature wear on the chain, idler gear or roller)
This has previously been well documented in the Com, I am thinking about leaving it in and giving it a go…

My “to do” list was getting ever smaller…
When I removed the clutch cover to clean and check the status of the plates and polish the cover, I found that the clutch mushroom was friction welded to the ball, it turns out that these parts have the same part number as used on the Z1 series from 1972 – to at least 1979 and after rummaging through some old parts bins, came up with the required replacement parts without leaving home.
It’s a pity that the clutch plates aren’t the same as well, because mine are just about on the service limit


I went for the satin over the mirror finish on the covers, this is #200-ish paper applied wet with kero and then hand polished with autosol.
In the end, I decided to run with a new pair of black and round Metler Lasertecs 110/90-18 and 130/90-17, they seem to ride and stick alright – has anyone had experience of using these tyres?
There was one final drama waiting for me and that involved getting a legit licence plate for it – the bike sailed through the physical part of the testing station process but it turned out that the certificate of title papers from the US had a typing error in them for the frame number (from back in the day) and the licencing authority here in NZ wanted to make a big deal over it (like, they weren’t going to give me a plate).
Got that sorted now (bless them), no more major problems I hope, Spring is here, warmer weather is coming and I am looking forward to my first club ride outing…

Looks like you've got a beautiful bike there almost looks like it just came out of the showroom congrats.

Good Job !! Glad to hear you put the brakes on and figured out the noise before grenading the engine. Saved yourself some major heartache.

I'll stick my neck out here and state that the previous owner probably sold the bike because of the noise and didn't want to get it to it. Glad to see the bike found you since it's obvious you have the talent to fix the issues.

Kudos to you !!

Good interesting write-up. A good thing that you discovered the cam chain roller condition too. Now that it is running properly, what is your opinion regarding performance and general riding experience?

Thanks for your comments…
Yes, I have always liked the big bulky look and sound of the Z13 (as they are known out here) and always meant to eventually get myself one – although, it’s easy to get distracted by life circumstance and that is why it has taken me 40 odd years (ha, I am running out of time to get all those old bikes I always wanted).
I had previously ridden (a mates) one back in the day, and riding this one brings it all back.

I particularly enjoy riding this bike, running with the standard suspension of the day (1979) is a good reminder of how far bikes have progressed in 40 years.
As you know… it is surprisingly light and agile through mountain road corners with a good tractable power spread (ground clearance could be an issue if you are in a real hurry - which these days, I don’t seem to be).

I haven’t had a chance to tap it out yet and see if I can get 140 Mph on the clock – with high bars and no fairing, I will need to take a couple of heart pills first…
Cheers
andy

Lauri Nurminen first brought that method of locking the standard CCT to my attention a while back & it's the way I'll be going when I swap out the ZZR1100 one on mine, luckily I kept the original CCT. Good work BTW