Monday, 3 August 2020

W/NG - time for some serious engine attention

As some of you may know, the W/NG hasn't been too happy recently - it's been consuming spark plugs at an alarming rate and has caused several unscheduled stops by the roadside - particularly annoying, because I'm lucky enough to live by the sea and a bike is the best choice of transport in the summer - you will never find another parking spot for your truck again if you choose to move it.

So, the W/NG is the go-to machine for local use, until it decides it isn't going to play nice any more. Next up is the SQ4... which has a flat battery and knackered points (my fault - embarrassing story), so now I know what a garage full of dead Ariels looks like:

So I've pulled the W/NG apart.

The rocker boxes come off easily. There is some head damage around one of the bolt holes, which I will probably leave well alone:

The piston is an oily mess and the top ring is in three pieces:

The small end is cratered but is dimensionally OK. I've not measured the pin or the piston yet, but the bore is 2.871 in the middle of the stroke (fore and aft direction) which is getting on for 40 thou over factory standard. There is no ridge at the top, so we will have to see what the piston dimensions are.

The valve guides are awful. I've not measured the valves yet, and I have no way to accurately measure the guides but the exhaust valve rocks maybe 1-2 mm at full open, the inlet maybe half that. The inlet guide is loose.

Then there is the big end. I can feel up and down play of maybe 0.5 mm; side to side rock is maybe 3 mm at the small end.

All in all, a good afternoon's work. A lot nicer than the morning, which was spent pulling one of these apart:

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