As usual, stendori info is 100% correct.
If you want, in a pinch, you can use a hose clamp for your ring compressor.

I would not use the old piston unless you really have to. The rings actually seal on the lands and you can not just file them accurately enough.

Oh sure it will run and might run pretty good but it might just bust the top off of the piston. If the piston was so hammered that the rings were stuck, that thing got hot; real hot!!!

That being said, I've done things like this many times and have had good luck.

By the way, I agree with stendori about measureing the bore.

 

well you were all correct

I took my cylinder and piston to the tech and proudly showed him the job on rings, but he took one look at the skirt of the piston and said you need a NEW piston [and rebore]. He said "these things will virtually work without rings but rely on a seal lower down to suck the fuel in"

so looks like no short cuts, just do it properly.

as for overheating, it seems the initial 10 years till I got it in 2004 the bike was in Mt Isa [ie like Arizona I guess] very hot and dry so no rust but it was not "loved", apparently used by anybody at a mine site. Anyway the radiator was totally blocked with thick hardened mud so combined with 100 deg plus temperature I can imagine it overheated quite a bit.

when I bought it I installed a temp gauge so I know it has not overheated since then, in fact the fan rarely comes on, so I guess the damage was done before [it always has been a bit hard to start].