Forum

[Leon Novello]

Is it using oil? Maybe a hotter plug ( B6HS NGK) will help.

[Phil Ashbrook]

I would say it's the unleaded fuel , I have had this problem , it's the additives in the fuel that gave me a black sticky soot , when I did the twin plug conversion it improved as I pulled the head I found the piston sooty on just one side so it was sending unburnt fuel out the exhaust , after the conversion my tick over was much lower and more steady .

[Beezabryan]

Black sticky stuff is more likely unburnt oil

[Ian Martin]

AFR is Air to Fuel Ratio. 8/1 aprox is enriched for cold starting. 14/1 aprox is for normal temp running once engine warmed up. Amazing what you can remember from all those years ago. I have absolutely no idea what Damhik is other than a predictive text cock up, perhaps ric could enlighten us. Ian

[Beezabryan]

Thanks Ian, I have been been aware of and understood carburation & petrol/air ratios for 60 years or more but AFR was a technicality too far for me

[Adrian]

Damhik = Don't ask me how I know, AFAIK! A. (Cheated and googled it!)