I ran it some more today and it was putting out less smoke. Pulled off the barrel to check the rings because it was hard to start, they are worn and the bottom ring had less wear so I swapped them over and now it's starts first pull even when hot :-). I have ordered a set of rings from the Outdoorking store. Information for future reference is below

Engine size is 22 cc, piston size is 35mm, rings are 2mm wide approx 1.51mm thick

Original part number is 04100000212

Replaced by part number 6686116

Current part number is 0410000021

Tanaka still make outdoor equipment and the 22cc engine is in use in a modern form. Rings are $17.85 each, 2 required.

https://www.outdoorking-forum.com.au/index.p...1084fc568&keyword=Tanaka+piston+ring

Expensive little suckers but good that genuine rings are still available and in Australia.

I would like to find a better muffler, mine is fairly rusty on the exterior.