spark plug condition

[vicvega]

Just changed the plug and although the colour looks ok, chocolately brown, it's quite built up with carbon. I've looked it up & it seems this is usually due to running cool, I think. Anyway its an avanti 30mil delly set up as per thread on here, done about 2500-3000 miles with this being the only issue, any ideas why . Haven't had the head off yet but was worried the piston might be coked up & overheat.
Cheers

[fairspares]

you need to post a picture of the plug to get a better idea but it sounds like your running ok ,after 2500 to 3000 miles plug will need a clean any way and should have some build up.

[Andy Pickering]

Mines the same, choccy brown but with a good build up of carbon, running cool would indicate that our Avantis do what they say on the tin ??, i noticed a good build up of carbon also around the bridge when i fitted the Franspeed and wondered if it was the use of the lawnmower oil, I also noticed Sideouts bridge the same on his gasket issue, I am also running a 30mm dellorto.

[mick1]

Just had my head and barrel off my Avanti. Done over 2k so thought i would check it out. The barrel itself was like new, no distortion of the exhaust bridge, no scoring or dis-colouration anywhere. The head though was quite "coked up" (ahh the good old days !!). I've been trying to run @3% but when you put 6.72L in or something else that isn't bang on a litre, the 3% is fairly inaccurate. After looking at the head and plug and talking to Ron i'm now trying for 2%.

[coaster]

The grade of plug used will have a bearing on how hot the plug runs, Ron recommends a B8ES for fast motorway use or even a B7ES.....I put a B9ES in mine without really thinking for the Coast to Coast run and it was quite wet when I took it out. I also use fully synthetic (Motul) at 3% in the Avanti but had previously used anything that was available so long as it was sold as 'Low Smoke' or 'Low Ash' which bI believe helps to reduce carbon build up.

[vicvega]

Sorry wasn't that clear, it wasn't the 1st time I'd changed the plug. This 1 had been in for about 500 miles or so, although I remember the previous 1 being similar. This was a champion have now put in a B7 so I'll see if that's any better. Might try going down to 2% aswell.