Honda-SOHC

That is a scary amount !!  I shall do some of the suggested checks over the weekend and failing that buy some of the M & P ones.  Thank you for your guidance and replies one and all.

Not that my answer may help you but I'm 2nd owner of a CB500/4 which I've had for 39 years and when I replaced my clutch plates for the first time some years ago I had one extra in the basket that shouldn't have been there !  Whether on factory assembly someone got carried away I'll never know but replaced with new set as supplied and still working after 30 years or so.
Maybe have a look at the SCHEMATIC pictures relevant to your bike on www.cmsnl.com can sometimes be useful.

Thanks for info Dave.  I have used M & P before so I do trust them and as you've tried and tested their coils that's another option open.  May well do that after reading 11 pages Ash's coil rebuild it left my head in a spin !  Like all these things, if you watch someone do it, it may not be such a problem as first appears but I just want to get up and running. 

Thanks for that idea.   I'll give it a try tonight if and when I get the chance.

Is it beyond the wit of man......... or anybody out else there, to realise there's a niche waiting to be filled with a  refurbishing  service for all of us four pipers wanting to retain originality.  I'm on my second set which are rusting out slowly in all the usual places but serviceable.
The downpipes are normally fine and show nothing more than maybe a light surface rusting (which will often polish out) so how about a bespoke manufacturer producing just the silencer section with an extended portion to clamp on to the remaining downpipe section !!