Reply To: Is it still a project when I haven’t done anything yet

Gents,

This really is interesting because I have had precisely the opposite problem on two occasions.  The first was with the 5HP Cloverleaf which would not run on a new set of Champions after I had rebuilt the engine in 2013 –  but has not missed a beat in the five years since I changed over to NGK plugs as recommended by a fellow 5HP owner.

However, more relevant to this thread is my much more recent experience with the 15/6.  I fitted new Champions H10C plugs when I rebuilt that engine early last year.  It seemed fine for the first thousand miles as I ran it in on a round trip to the TOC annual rally in Scotland.  Admittedly there were a few hiccups but, as I found I had the issue of a cracked manifold,  I simply assumed any lumpy running was down to that rather than anything else.  However, armed with a new manifold, we set off 2 weeks later to join the Brittany Clubs rally and then I realised I still had misfiring problems.

After discussions I changed the plugs – I was carrying a spare set of new Champions.  All was well initially but within 500 miles the misfire had returned.  At the suggestion of Phil Allison I bought and fitted a set of Bosch WR8B+ (+20) plugs as soon as I got home and have not had a mis-splutter since.

B…………………