Hi all, Just wondering what spark plug I should be using in my 500T. It's running a standard BTH TT magneto and the plug cap has no resistor in it. I do get a bit of sooting of the plug but I guess that's from running slow a lot.

Thanks in advance.

You could always speak to the green spark plug company. I did when having issues with my Panther dieing in the hot summer a few years ago. The plug he recomended is still in and the bike never misses a beat.

I still think your problem is the mag getting weak,especially the way it was behaving yesterday. The plug being sooty could be as much that its burning oil as a rich mixture,either way a contaminated plug will need a stronger spark to fire.It was blue smoking quite a bit when I saw it. Stevo who was riding with me rarely changes the plug in his 500T,(Can't remember what plug it was -NGK B5es or BP5es ? ) but the motor and mag are in good shape,never misses a beat and is a treat to use.

Thanks for the replies.

Is there a way of testing the mag, bearing in mind that it's probably getting weak when it's hot?

I've never had the engine apart but she only seems to smoke when I get it really hot. Probably due a 'going' through.

I also wonder if the fuel I'm using is contaminating the spark plug because the plugs are hard to clean using a wire brush. Using normal unleaded.

Was going to try a different plug first to see what difference it makes if any before going in deeper.

 I have ridden 500t's for about 40 years and always use NGK plugs because in my work they have always given the best technical support and seem to operate across the widest temperature range. I used to use BP5ES but sometimes have a misfire or need to fit a new plug in longer events. Recently I have been using Iridium BPR5EIX and all the problems seem to have gone away. I use a standard BTH magneto.

 

another one for ngk iridium plugs since fitting them in both my greeves outfits and a jawa enduro , after two years of hard use i have had no problems