When should you replace a spark plug?

[muskrat]

G'day Fellas.
I had a hell of a job starting the A 7 plunger yesterday. OK it was minus C but never had to kick her more than twice in the past and with no choke fitted. Swapped out the B7's for B6's and started straight up.
Cheers

[Greybeard]

G'day Fellas.
I had a hell of a job starting the A 7 plunger yesterday. OK it was minus C but never had to kick her more than twice in the past and with no choke fitted. Swapped out the B7's for B6's and started straight up.
Cheers

Take care mate 🤔

[chaterlea25]

Hi All,
Slymo,
In my case it certainly is not the mag!!
The problem as such started when E5 became the only fuel available here.
Two years ago when I fitted the electric starter I took the BTH (original not the modern thing) to my mag man,
On test it passed the spark gap test at 105 rpm. After a clean up and 're magnetise it passed the test at 95rpm.

John

[Worty]

Got through a few plugs (B6HS) when my maggie was packing up.  Fortunately, I saved them and started using them again.  Tend to use them until a glitch shows up, clean them, put them back - if the problem continues I change the plug, if it doesn't it's 'look elsewhere' time.

On my 1970s two strokes, I ran the plugs until they were thin and pointy - still worked though!  Just looked at the ones on the Kwaka and they look fine but crusty round the top - who knows how many miles they've done.  On my son's Citigo, change is every 40k, and they still work and look good (kept those also).