Plodded on with checking valve clearances.
If I've measured things correctly there are two exhaust valves, one front, one rear and both on rhs that are out of spec.
Exhaust spec = 0.2mm - 0.3mm.
Actual front right: 0.15mm gauge fits, 0.2mm does not. Therefore it's too tight and requires a new shim.
Actual front left: 0.2mm gauge fits, 0.25mm does not. So it's in spec, on the tight side but no shim is required.
Actual rear right: 0.15mm gauge fits, 0.2mm does not. Therefore it's too tight and requires a new shim.
Actual rear left: 0.2mm gauge fits, 0.25mm does not. So it's in spec, on the tight side but no shim is required.
Inlet spec = 0.1mm - 0.2mm
Actual front right: 0.1mm gauge fits, 0.15mm does not. So it's in spec, on the tight side but no shim is required.
Actual front left: 0.1mm gauge fits, 0.15mm does not. So it's in spec, on the tight side but no shim is required.
Actual rear right: 0.1mm gauge fits, 0.15mm does not. So it's in spec, on the tight side but no shim is required.
Actual rear left: 0.1mm gauge fits, 0.15mm does not. So it's in spec, on the tight side but no shim is required.
Does the above make sense / seem okay?
The smallest feeler gauge available is 0.05mm so that's the best resolution obtainable.
I've kind of messed up a bit because it was my plan to measure the clearences and then order the appropriate shims if required. But didn't realise that I can't determine the size of the existing shims on the rear if the front is in bits because I can't turn the engine to get the rear cams in the correct position to get at the shims.
So had to order a full shim kit which will be two to three working days delivery and will leave both front and rear cams intact until it arrives. And it's much more expensive for the full kit. Bugger.
The front centre spark plug came out really easily, hardly any effort required to turn the wrench. The plug threads and the ceramic on one side looks a different colour compared to the rear plug which required a firm effort to remove.
I wasn't thorough enough cleaning the crap off from above and around the front cylinder area. Bits of dust dropped onto the inlet cams. The gauges felt nice and smooth between cam and bucket so I don't think any debris affected the measurements.