Cam End Plugs + Stripped Valve Cover Threads

In the absence of a specification, I start with the middle bolts and radiate outward. Just my own preference.

There should be a sequence in the manual but if not the rule of thumb is the same as ahead, loosen from the outside in - tighten from the middle out (if f there is any distortion tightening the ends first will prevent the middle from pulling down)

On the Z1s and KZs there is no specific tightening sequence for cam cover bolts.  There is one for the cam bearings though, and they are the same size.  From memory I think the general torque spec is around 95 to 110 inch lbs, but like others who have chimed in I don't go that high.  I normally go about 75 inch lbs.  This is because the head is 50 years old and has seen a lot of bolt removals over the years that tends to wear down the threads over time.

One thing not mentioned yet is to clean your thread holes thoroughly.  I blow compressed air into them.  Also clean the bolt threads to make them slip more easily into their mounting holes.  I use a wire brush.

Some Updates: 

- The rubber cam plugs were a replacement for my OEM plugs. With some Permatex Black and a Helicoil repair I was able to properly seal my valve cover - no more leaks! 

- While the bike was apart I rebuilt my starter clutch. I finally treated myself to a electric impact, which made short work of the rotor bolt (which had me stumped last time I tried to tackle the job). I did have to order a flywheel puller to actually get the rotor off, as none of the hardware stores in my area had a M18 x 1.5 bolt in stock. 

- I tracked down the last oil leak on my bike - I had a slow but steady weep coming from the Cam Chain Tensioner on the back side of the motor. Oil would drip from the tensioner onto the transmission case (?), pool, and then run down the side of the motorcycle when it was on the kick stand. I could never quite track it down as it seemed like oil was coming from everywhere, but with everything else sealed up I finally figured it out. Of course, I figured I would just torque the cap to spec (20 ft. lbs per my manual), which resulted in my snapping the cap off of it's threads. D'oh. I think my torque wrench needs calibrating - 20 ft lbs is the very low end of it's range.

- New cam chain tensioner, cap, washer, and O-ring are on their way, but until then the bike is parked. Are there any special procedures required when changing the tensioner? My manual pretty much says just to remove the old and install the new. I ordered an OEM replacement as I don't want to risk screwing up manual adjustment. 

A fasteners job is to create a clamp load between two surfaces. When you apply torque to a fastener, you hope that washers, cleaniliness, lubrication, gaskets, threads, and metal properties reflect the situation that the torque specifications was created in. The difference between a dry aluminum bolt in an aluminum hole and a lubricated one is 20-30%. Cast iron versus aluminum is significantly different. The point is to help you visualize that in some cases torque rises very slow, and very quickly in other cases, and this messes with the clamp load you are trying to create. For example a thick spongy gasket, torque would rise very slowly and the clamp load may relax over heat and time. Another example is very hard and lubricated fasteners and threads, torque rises extremely quick and its easy to break the internal bonds of threads and fasteners. 
The point is to create consistency. Of course experience can do that. If you do that by using a torque wrench, make sure that all of the properties that skew the measurement are held constant. Also, only measure while the fastener is rotating. Static friction will fool you into creating a clamp load that is too low.

When fastening a head or valve cover imagine there is a bubble trapped under the valve cover and that if you fasten it from outside to inside you will trap the bubble. you want to iron the bubble out from underneath the valve cover. start in the center and work your way out. Automated head assembly runs all fasteners to 90% from inside to outside. then the final 10% starting from the inside again. if you want to be safe let it sit a couple days and or heat cycle it.

Once the clamp load of the joint is correct, applying more torque only works against you with one exception. Fasteners loosen from vibration. very tight, hard, lubricated fasteners tighten and loosen quickly from high frequency vibration. The correct window is small. ou do not want it loose or it will come loose. Soft dry metals are resistant to vibration. 

New cam tensioner installed, so I was finally able to start the bike. Of course my battery had gone flat from sitting, but I was able to jump it from my Goldwing. I ordered and installed a new AGM battery to be safe  - I knew my old one was on the way out. 

The Good: 
-The bike now starts quickly on choke, and will settle into a steady (albeit slightly high idle) at ~1100 RPM. I haven't dialed in any idle adjustments due to the issues below. 
-I don't see any remaining oil leaks, but time will tell. 

The Bad:
-The engine feels healthy and normal until I try to rev above 2000 rpm. It then hits a bit of a 'wall' and will only sputter in place. Engine speed will not accelerate past 2000 rpm even at wide open throttle. The bike backfired loudly yesterday when I was messing with it. The throttle is actuating properly, and snapping closed when released. 
-I've multi-meter tested all my ignition coils, wires, and spark plug caps. All tested within spec, and I saw spark at all four plugs when testing. Red/Black wires running to the left coil (Cylinders 1 and 4), Red/Green running to the right coil (Cylinders 2 and 3). 
-Weirdly enough plugs 1 and 2 (numbering cylinders from left to right as you sit on the bike), were dark and seemed fuel fouled (smelled of gas). I initially chalked this up to my starting attempts earlier in the week, but cleaning and re-installing the plugs did not solve my issues.This doesn't track as a spark issue to me as plugs 1 and 2 fire from different ignition coils.

I'm planning to check the timing advance mechanism on the right hand side of the bike tonight. If that mechanism is functioning, I am running out of easy checks to do. Has anyone encountered this kind of issue before? I recently rebuilt the carburetors (see my previous threads), and the bike ran well as recently as a few months ago. I've only used ethanol free fuel. I am hoping to avoid diving back into the carburetors unless it's 100% necessary. I did remove and clean the ignition pickup/pulse coils a week back. I checked and as far as I can tell I reinstalled them correctly with the small magnets facing inwards. Both tested within their resistance specs. 

Any and all help/advice is greatly appreciated. I can get a video tonight after work if it would be helpful. 

20ft lbs on the cam chain tensioner bolt? if your talking about the 6mm bolts for that tensioner I would only go to around 75 INCH pounds. What manual are you using?

No, I was referring to the 19mm cap on the tensioner. It holds a spring and a small pushrod in place. Following the advice of others in this thread, I hand tightened to what felt right. The mounting bolts for my tensioner were 10mm, which I also hand tightened. So far no leaks. 

I have a Clymer manual. Don't remember the exact years/models but it includes the police bikes. 

When you talk about 10mm bolts are you referring to spanner size ? If so these are the 6mm bolts cra-z1 is referring to (6mm is the thread size)

Yes - I meant spanner size. They fit a 10mm wrench. 

Those are M6 (6 mm) bolts with a 10 mm head.  You have waaayyy overtorqued them.

The M6 bolts with 10mm heads were hand tightened with a 10mm wrench. I purposefully did not apply significant torque to these bolts to avoid stripping or cross-threading. The 19mm (spanner size) 'cap' bolt was hand tightened with a 3/8ths drive ratchet. At no point in the install of the new cam chain tensioner did I use a torque wrench, per the advice in this thread. I hand tightened everything down to what 'felt right'. Nothing was torqued to 20 lb-ft. I previously tried tightening the 19mm cap bolt to 20 lb-ft and learned that lesson the hard way. 

I ran the engine for a bit longer yesterday, to see if I was running on all cylinders. The exhaust leading from cylinders 1 and 4 was significantly cooler than 2 and 3. So I do think I have some kind of spark problem.I'll continue troubleshooting and will update this thread when I figure it out.