How often should I change my spark plugs?

Assuming that after a visual inspection and gap check they are in good nick?

Implication being that I’m wondering if they can stay in for longer than the official service limit - e.g. like for 20k if they look ok rather than the official 8k.

I think they last MUCH longer than that - and I don’t think it is “normal” to change them at regular service anymore…

Fine if your mix is fine… I don’t see any point in changing them after 8,000 miles if they’re doing the job well enough

Check the colour and the gap, the electrodes can wear down…

Thanks fellas - yes I agree - I take a peak at them now and again but so long as they look/perform ok I don’t change them as regularly as I used to.

Modern spark plugs are probably good for he life of the bike providing the mixture is right.

Too rich, you’ll need to clean them, too lean they will burn their electrodes.

Between, it’s the ceramic material that might give up but that will show up in hair line cracks, poor starting, going ape in the rain and the like.

Yeah - also seems like a scandalous waste of resources to chuck all that metal in the bin every few thousand miles.

Was ever thus.

I once serviced a Lanchester (that’s an old make of car) probably about 30 years old at the time with quite a lot of miles on the clock but running like a dream. I had to phone Lodge to get the current equivalent spark plugs and gave them the old numbers.

I was told that Lodge hadn’t made that number spark plug for over 20 years.