Forum

[stefaand]

Norm: I just want to ride the bike, and have it as reliable as possible. At first I wasn't even going to repaint it, just preserve the patina, but it's too far gone sadly.
Simon: Thanks for the info on the pinion extractor. English thread and sizes are quite rare here though, and only come in a bag of 10 usualy at a specialty store, so I will have to have a look around what I can find. I absolutely agree, I would love to just be able to slap it back together and ride it, but I can't just do that if it needs attention.
Papasmurf: You are right, we are speculating a bit, and to be honest I suppose I'm looking for excuses not to have to replace it! Measuring is knowing.

[Dennis C]

Quote "(I can't believe the from new bore piston/bore gap is 0.08-0.1 mm either.)Seem s bit large by modern standards.)"

Papasmurf this is a 1950s bike it does not understand modern standards.

[simon]

I set my ring gaps at .015" after I believe Phil Irving's advice in Tuning For Speed. .005 plus .003 for every inch of bore. 1mm or roughly .040" is huge. I suppose it might relate to the wear limit although .8 mm also sounds excessive. As far as getting an imperial thread goes I suggest seeing if you can find someone with an old Englsh hobby lathe such as a Myford. They are set up for cutting Imperial threads and you can make the tool out of free machining steel so it's reasonably easy work.

[stefaand]

Good news. I checked the bore, and it's still within spec! (0.36mm within spec) Should I just sap on some new rings? Can I do a quick hone as well or will this affect the play too much?

[Gwilly]

To hone or not is a subject liable to raise difference of opinion..

Most of us over a certain age would always hone for new rings, or bore if there's the slightest ridge at the top of the piston travel..

That is what we were taught as being good practice..

There is however an argument for not honing if you want to preserve what little metal you have, close to the limit..

The rings will still bed in but i should think take a little longer..

Think about it, the rings won't seal perfectly until most of the cross hatching has worn down giving a nice smooth shiny surface which is what you have now.

So why create even faster wear on metal you can ill afford to lose...

Its an interesting hypothesis which ever camp you choose..

[simon]

I would suggest a light deglaze with some medium fine wet and dry but probably no need to hone. I know some people say you should run the rings in on a unmolested bore but this is likely to take a very long time and if the rings don't bed in then the oil,will keep burning. An even scuff up with no up and down scratches and 1000 careful miles will see you set up for a long time.