Z1OwnersClub GB

Had my bike running this morning after checking all the little leaks and solving most.
Engine was sounding ok but I got the feeling something wasn't right.
Could hear what sounded like a knocking and had some miss firing.
On investigation
Plugs from cylinders 1, 3 & 4 were dry but sooty.
Compression on those cylinders ok
Plug from cylinder 2 clean but the gap was 0 and it looked like it had been hit! I know it was right when I put it in.
Also 0 compression which has gone down from 8!
Put some oil in the pot and tried again but nothing.
Sounds bad to me.

Think your right about it sounding bad Wayne,something a miss on that pot looks like head off to have a deco to me, valve at a guess,you have had quite a battle with this bike but look at it as a steep learning curve,you are learning as you go all of us who are willing to have a go, have been in this position at one time or another,keep at it,will be worth it in the end..Paul J

Thanks Paul I won't give you and yes must be the valves although I religiously checked and double checked them.
What do you think might have gone so wrong, bearing in mind I did have good compression.
What causes sooty plugs, they weren't too bad and might be how they should be.
What would have closed the gap up on the plug?

Sooty plug = too much fuel
plug closed = been hit from underneath

Ok hit by piston so that can only mean piston riding too high or plug sitting too low?
Or something broke in top of cylinder and hitting the plug, strange. Maybe a magnet in the pot will pull something out?

Wow that has completely thrown me!
Cam cover off and checked valve clearance
Numbers 1,3 & 4 within tolerance but 2 way out exhaust 0.006 and inlet 0.015.
So I then checked through the spark plug hole and could see the top of the piston was pitted. I then checked the spark plug and as well as the gap closed the outer wall was also pitted.
I attached a fuel his to the Hoover and pushed it in and it sucked up a piece of solid metal the size of a the head of a match!!!!!!! You can clearly see where it has taken a beating, smooth but I can't for the life of me work out what it might be.
I checked the valves so many times and they were all fine.
I'm thinking of re shimming number 2 cylinder and having another go? That should sort out the lack of compression.
I don't think the piston head is too damaged.
Any thoughts?

Photo

Can I email you Pigford?

Its not the ball valve from the end of the compression pressure gauge or tip of the positive stop tool is it?
Ball from vacuum gauges?

AL

Just checked gauges and don't think they had a ball in them. It's strange because it doesn't look like anything I've seen before. It's smooth where it has been jumping around inside the bore but how it got there I really don't know. I have completely re built the engine so it must have come from me, my wife doesn't go anywhere near it !!!!!

perhaps your wife has got the hump with you spending all your time in the garage & has sabotaged your engine. seriously though you need to at least remove the head to investigate what has happened. if something has been flying around in the cylinder it may have damaged the cylinder bore

Ha ha I thought that but she knows me better than that and would see this as a challenge. I understand but surely if I can get the compression back it should be ok. I want to get the bike running as best I can as I have never seen it run. I can then go back and tweak stuff during maintenance and service.
I have thought things through in my mind and can't think of anything that could have sheared, snapped or broke off that would leave something like this in the bore. I'm a little worried that the valve gaps were good and now the inlet is at 0.015 which is a big change.
I can see the valve compressing and lifting and I can see the valves through the spark plug hole. I know the top of the piston is pitted but it looks complete.
The walls if damaged will show up when I re check the compression.
Can anyone think what can possibly enter the chamber from something that has broken within the bike itself?

I don't want to be a harbinger of doom Wayne , honestly i don't .
Gap opened up and no compression on that cylinder only means one thing to me .
Sounds like bent valve
An hour will have the head back on the bench and you can re use all your gaskets .

I agree, definitely a bent valve holding the face off the seat. I've seen loads of "blow ups" over the years and they rarely damage the bores unless the piston or a ring has broken up. You don't say what the bit of metal is. Is it aluminium or steel or what? perhaps something has either been drawn in thru the airbox or was dropped in when putting the carbs on?

Hang in there...

Z1 yes sorry I thought I said, it's steel and I thought something like that. I was religious in cleaning stuff and shocked to find something like this in the chamber. But in saying all that I can't dismiss the fact it was in there.
So it's steel an as I said the size of a match head. It,vs been smoothed off due to constant jumping around in the chamber. I feel like I recognise something but can't place it. It's got like taper on part of it.