Honda-SOHC

I'll try to look out for it although I have to go a long way to get to a station so usually have to get whatever they have.

I would agree with that, take it to someone who knows what they are doing.  I was told by Steve at Piston Broke in Bristol that Honda tolerences were really tight and he correctly rebored my 500/4, very close indeed.  He warned me I would have to run in very carefully but that there is no point in taking out more metal than is needed and that it would last longer as a result.  I followed his instructions and 26 years later it is still going strong.

If the pitting is really deep there are other pistons that fit CB350k such as Kawasaki GPZ750 (66mm).  Same crown and gudgeon pin size and valve cutaways fit perfectly.

On my 500, I noticed one of the float bowls is weeping a little and realise I might have to replace the seal.  I thought, while they were off it might be a good idea to do the seals on the jets at the same time.  The last time I overhauled the carbs fully was 26 years ago and possibly, back then, I used the original ones anyway.

Before starting this mini project I've been looking online but it seems hard to find kits that have just the O rings, I don't want jets or float valves or anything.  Has anyone found such kits anywhere?

The other thing I might need is a supply of float bowl screws as the original ones are a bit chewed.

Those of you that know me will realise I won't be able to stop myself from saying, Scottoiler at this point.  I have one on my 500 and it is simply brilliant.

Mine is placed where the air filter used to be so you can't even see it. 

(Replacing the air filter with individual filters is a controversial subject but set up correctly and with non-standard exhaust, bigger main jets, mine runs great.)

well, I have assembled the brake caliper, very easy and quick but suddenly realise I may have made a mistake.  The new piston is stainless steel rather than the original chrome steel type and therefore will be prone to electrolysis with the aluminium and the bike spends most of it's time outside. Although the old type of  piston goes rusty after a few years, it doesn't affect the caliper.  Has anyone had problems with this and should I order an original piston?

Thanks John, I did think that but I haven't got any and wanted to finish the job today.

the part just seals the balance tube between the air filters.  As long as you get a seal into the metal tube anything will work, or you can do what I did and ditch them altogether and use better carburettors and filters.

also seems a lot of money.