This is part 5 of the engine part of my Z650 restoration - this time I'm digging a bit further into the innards of spare engine number 2.
So it's time to get the sump off, to see what lurks inside and get an idea of the state of the bottom end of the engine. The last thing I did last time was take the oil filter cover off and remove the oil filter, which needs to be done before removing the sump.
All photos by me - this is a pretty one of the end result, because it looks better as a Hive thumbnail :)
This is the engine rotated slightly in the engine stand to make it easier to get the bolts off, but not turned so far that anything nasty falls upward into the engine. Note the drain can underneath ready to catch the oil that will inevitably fall out, even though the engine notionally had the oil drained years ago.
The sump bolts came undone really nicely, despite many years of sitting and potentially corroding into place. Despite surface rust on the bolt heads, that's a good sign !
This image shows the state of the sump when it came off. It was nasty ! The actual oil that was in there was very clean - it is a really good sign that it hasn't been contaminated with water. However, the bottom of the sump was full of sticky black debris. There was old hylomar gasket sealant, and far more small pieces of metal swarf than I would like to see. It makes me very glad I took the sump off, I wouldn't want any of it recycled back into a newly refurbished engine.
Even more worrying is the state of the oil pump filter screen. It is a sticky coating of old gasket sealant and bits of metal. Inspecting it further will be a job for tomorrow. How it pumped oil at all in this state is a mystery to me !
I should probably explain a bit about the history of this engine.
It was the second one I fitted to the bike; the original, which is now spare engine #1 had problems, in particular a stripped output shaft thread which I'd bodged with Araldite to stop the sprocket falling off and keep the bike running.
So I picked this engine up for £50 from a friend who had had it sitting around in cardboard boxes for a while. It was dismantled down to the last component. Over a winter, I rebuilt it with great care in my bedroom (I was living in a shared house at the time). Only when it was reassembled did I discover that it was too heavy to just pick up and carry downstairs, so I put it in a crate and slid down the stairs on it a bit like a toboggan !
Fitted to the bike, it was good for about 15,000 trouble-free miles. Then one February day my main bike I was using to despatch on (a BMW K100) broke down. I had to keep working, so switched to the Z650. The company I worked for sent me down to do a delivery at a place called Chew Magna, the other side of Salisbury Plain. By the time I'd done the delivery, it was late afternoon and the temperature had dropped to below zero.
All I wanted to do was get home, and being honest, I pushed the bike far, far too hard. On the long, slow uphill climb back onto Salisbury Plain, it starting running really rough. Over the next 20 miles, it got worse. Under normal circumstances, I'd have stopped and called for recovery. But this was in the days before mobile phones, and with the temperature at about 5 degrees below freezing and snow starting to fall, I had no choice but to try and nurse the bike on as best I could. No-one else was on the road, and if I stopped, I knew they'd just find me frozen in a snow drift the next morning.
Somehow, the bike got me all the way across Salisbury Plain, to near the gates of a road maintenance compound where I was able to get help. When we finally got the bike home and I was able to investigate what had gone wrong, I discovered that she'd been running on just a single cylinder. Two others had dropped valves and a third had lost compression. It is a testament to Kawasaki engineering that even with that abuse, the bike had kept going long enough to save my life !
I did a full top-end rebuild, drained and replaced the oil and just kept on riding her - dumb, I know, but it was the 1980's and Z650's were treated as bullet-proof hacks back then. I am guessing that most of the metal bits I've found in the sump date back to that incident. Shortly afterwards, one of the input flanges broke when I was replacing the carburettors, which is why I took the engine out and replaced it with engine #3, the one that is currently in the bike.
I've spent the evening giving the inside of the sump a really good clean. This is the end result. No metal bits !
Three jobs remain for tomorrow;
- Remove, check, and if necessary clean the oil pressure relief valve.
- remove and clean the oil pump screen, and have a look inside the pump. Luckily I know a place I can get a replacement screen if this one breaks (although it's pricey !)
- Check the condition of the three o-rings - they look good, but I want to make sure they haven't hardened too much.
When I next order up some new parts, I'll also see if I can get one of those magnetic oil drain plugs.
This is the outside of the sump. I'll probably give it a quick clean, but since I'm aiming for a mechanically sound rideable restoration I probably won't try to polish it to a concourse finish. After all it lives underneath the engine, so if someone can see it the bike will probably be upside down we me underneath it, and I'll have more serious things to worry about !