An appeal for help

[Reckless Rat]

Whilst BP5HS plugs are probably the correct heat range, they are extended nose and as such will soot/ coke up very readily. I ovrcame a similar problem with a set of B5HS plugs. Two full turns out of the main jet is the usual starting position but if your plugs are still sooting up it's set too rich. Try weakening the mixture a couple of flats at a time until it runs cleanly.