TOPIC:

.I have now picked up the 2 valves that needed to be tipped. I used a boat engine shop not far from me .Only paid 30 usd.The valvetips had a rugh surface and a sharp edge so i did the finish work .Placed some wetsand paper 500 then 1000 then 1200 grit on a glass table and by hand just smoothed out the surface a little.
Then used a dremeltool and rounded the sharp edge off a little. The edge has to be rounded so that it does not damage the valveseal and risk scratching the valveguide when installing the valve again.

I was surpriced how soft the metal was it only needed very little sanding to smooth out the tip.I then started thinking that the "hardened tip" was damaged by the grinding at the boat engine shop so i tested the tip of another yamaha valve that has not been tipped.I used some coarse wetsand paper on that and found the metal was very soft on that valve to so i guess it is normal.I tried to find out more about valve tipping and hardened stemtips and found that if the valve is magnetic it is okay to tip the valve as much as needed. This exhaustvalves on the kz900 is magnetic from the middle of the stem and up to the tip so it should be no problem. Next now is to buy 4 more shims .Strangely i have 10 extra shims but non with right thickness typical!!

The work on head was now to replace the studs ,but had to give up on them .I only got 3 of them replaced because the risk of breaking the aluminium head or snap off a stud .The plan was to use stainless steel rods but ended up buying the galvanized  oemThe studs are okay but rusty but i can live with that instead of breaking something.

I just finished the same operation on my 78 head. I think the trick is to put heat on the aluminum, not the stud. Then instantly rap in the end of the stud with a sting (not heavy) blow as you are trying to unscrew the stud.  It may take a few repeat cycles but usually works.  Hope this helps.

Vinsky wrote:

I just finished the same operation on my 78 head. I think the trick is to put heat on the aluminum, not the stud. Then instantly rap in the end of the stud with a sting (not heavy) blow as you are trying to unscrew the stud.  It may take a few repeat cycles but usually works.  Hope this helps.

Thanks for your advice Vinsky ! I will try that too
 

I have now for several hours tried to get one more stud out. I tried to heat only the aluminium like Vinsky suggested to. Thanks again Vinsky but i think the 1978 kz1000 has 8mm studs so these tiny kz900 6mm is more fragile . I have also used freeze spray on the bolt so it got white and heated aluminium and tried to let it soak overnight with penetrating oil but nope no luck.Also used a spanner on the double nuts and a vicegrip plier simotaneously to get a even pull on both sides.
I can se and feel the bolt twist a little in the outer part , but it is not moving at all so that i guess  is the sign that it will snap or the aluminum crack in next millisecond so i will leave it. I have removed stubborn exhaust studs before ,but that has been 8mm studs. These tiny 6mm i dont dare to push more . At least the studs that i cant remove will get a new nut

If the stud has enough thread to securely attach the exhaust flange, "discretion may be the better part of valour" 

Wookie58 wrote:

If the stud has enough thread to securely attach the exhaust flange, "discretion may be the better part of valour" 

Yes Wookie58 that is what i think afterall  it is only the outer 3mm tip of the stud that is visible after installed the exhaust and nut. So i will just brush off the rust on the studs. But since i had bought new ones i was eager to replace all but not so much that i break anything and ending up sitting drilling and helicoiling or even send the head for welding this summer

 

Have now got the shims needed and installed those .i have already bought a shimbucket holder tool so i tested it and it worked great. Then last night i started to test if the exhaust-flange parts is okay.I just used a drop of superglue to hold them together .There is a problem...... The unit with the coppergasket does not get far enough into the head so it is a space about 5-7mm .I dont have the pipes in my flat =) so i can not check how thick the flange on the pipes are ,but i guess they are not that thick.Maybe there was 2 gaskets in there ?I dont remember taking out 2 exhaustgaskets.

Update Silly of me i see now that the C shaped clamps will maybe be sitting a little more together when clamping around the pipe so then i guess its okay.

I use 1 wrap of cellophane tape (scotch tape) around the collars to hold them on the pipe and some grease on the copper gaskets to make them stick to the exhaust port when installing.

sf4t7 wrote:

I use 1 wrap of cellophane tape (scotch tape) around the collars to hold them on the pipe and some grease on the copper gaskets to make them stick to the exhaust port when installing.


Thanks  when i took the exhaustpipes off in september i could see the po had used some type of tape when installing.

 

So the engine is back together in the bike i can make a little writeup on the camchain and stuff later.The bike was hard to start and had to take a shortcut using starterfluid in the airbox.
When it fired it sounded a little like a dragster . i had some problems that cyl 4 pipe was cold i checked spark and it had spark then looking into cyl the piston was wet so then i knew it had both spark and fuel.Then turned the mixturescrew that is on the underside of my z1000 carbs inward to make it leaner and finally it fired on that cyl to.Then when started it did bog down when blipping throttle.Checked the plugs again and they was black.So since it was rich on all cyls i adjusted the mixturescrews inward a little on all carbs and then it had a good responce when blipping/twisting the throttle.Now to the problem and it is about electrics that i hate .I still have the dyna-s installed that i think is a cheep chinese copy.I have bought a boyer bransden system but wanted to wait installing that firstly because i dont understand the instructions and secondly because i dont want to fiddling with strobelight and running the engine at steady 5000rpm to set the timing.The engine needs to be run on the road to seat the rings. I have installed new coils bought from Z1 enterprice they are marked emgo .so installed them and used the old dyna-s timingplate and picups. So the problem that i need a answer on is this. I used a test light to set the electronic timing it was turned on at the advancer mark .Then i noticed that it also turn on about 3 mm after the F mark ? then i tried to start and it was impossible without starterfluid and it stopped fast.  Then i set the ignition so that the testbulb light up 2-3 mm before advance mark .Then the bulb lights up exactly on the F mark .then the bike fired up easy. The question is  is this setting with the timing set 2-3mm before advance mark okay?  or is the dyna-s broken?  I read some instructions on how to set up the dyna-s and it says to set it exactly at the advace mark when the rotor is turned fully. when i do that the F mark does not match.It lights up the testbulb 3 mm after the F mark and is almost impossible to start. So now it set about 3mm before fully advanced mark and exactly on the F mark Anyway i took the bike for a little ride yesterday and it runs good. that is when i adjusted the timing so it is 2-3mm before fully advanced mark on the engine timing metal advance mechanism.Can this damage overheat the coils???Or worse overheat the engine??