More progress today.
I paid Mike a visit to pick up the head and barrel (now bored and honed) plus drop off a disc and carrier that somehow ended up with all my Ducati parts but neither of us know what the hell it’s off.
Anyway. Once home I lost another hour of my life filing piston ring gaps which is a truly detestable job involving constantly putting the rings into the barrels, check the gap with feeler gauges then file a bit more off. I now have 0.016” gaps on the second rings and 0.012” gaps on the top ones so all is well there.
After that I decided the way forward was to fit the inner circlips and bung the pistons into the barrels so I can drop the whole lot on as an assembly, fit the pins and outer circlips then it’s job done. I know a lot of people fit the pistons on the rods and then lower the barrel onto them but on a single or a twin I find it easier to fit pistons to barrels first.
After that I had another look at the head and to be honest it’s a fucking mess. It’s had one new valve seat fitted but I only noticed today that one seat has been ground down miles more than it should. There’s also the small issue of two cracks going into the spark plug tapped hole (I knew about this before) which can either be ignored or welded and remachined. I’ve got new valve guides and as Mike pointed out, heating the head to change the guides could do all sorts of bad things to the cracks so I need to make some phone calls and have it done.
You can see the cracks on the left hand side as shown above and the deeper grinding on the seat top right of that plug hole. The one replacement seat is top left on the other side.
More confusing is that when you drop the valves in one sits about 1.5mm proud of the others! That’s a serious what the fuck moment but it can be removed and oversized, correctly ground seats fitted if I throw money at it.
Bottom right is the valve that sits proud compared to the others.
I hadn’t bothered looking too closely at how they seated when I stripped the head but even if I lap them in it’s a recipe for disaster so it needs fixing. It’ll be a pain in the arse because I’ll need all new shims but such is life, get on with it. I’ve got guides and seals, the valves look ok and aren’t bent but it’s obviously had a top end disaster at some point in its life and I don’t want it dropping a valve or a lump of cylinder head when I’m thrashing the life out of it.
Both plug holes have had helicoil inserts previously fitted and new ones are cheap so they’ll be replaced though one would have to go when it’s welded. I’m not even going to start to think about what this lot will cost me