Norton Commando Fouling Plugs
SPARK PLUG TECH TIPSAvoidover tightening Spark Plugs, especially when installing them in a hotengine with aluminum heads. A plug that is over torqued when the engineis hot can cause crack(s) in the head as the engine cools down.Generally speaking, you want to run as wide a plug gap as possible.Having to reduce the size of the plug gap once it has been wellestablished can possibly been an indication of problem manifesting inthe ignition system.
This is common in the magneto systems as theygenerally need smaller and smaller plug gaps as the magnetodeteriorates.A sparkplug that appears to have a pinkish hue to the electrode has either beenoverheated or has been subjected to pre-ignition. Pre-ignition is theresult of the cylinder firing before the plug fires. Carbon buildup,untrimmed gaskets, sharp edges, too hot of a plug are just some of thecauses.Littleblack splotches on the insulator of the plug can be caused bydetonation, which is basically an explosion in the cylinder after theplug has fired. Shitty fuel, too far advanced timing, engines that haveseen a lot of miles, or were improperly assembled can suffer detonationwhen oil gets into the combustion chamber and reduces the octane of thefuel. If that happens, a rebuild is the only repair, otherwise retardingthe timing, and/or using better fuel usually does the trick.Aluminumdeposits on the plugs means that the piston is overheating. This iscaused by either a lean mixture, or having the timing too far advanced,or a combo of both.When youhave the head off, check the projection of the plug into the combustionchamber. If there are threads showing you will want to either usewashers to pull the plug back up or better yet switch to a shorter plug,if possible.
For many years now I’ve been a fan of small electrode iridium plugs, generally using NGKs. This is because I learnt from experience that ‘normal’ plugs would fail too easily in a race / track bike. I started running them in race bikes, liked them and stuck with them.Recently I added a restored T140 to the shed inhabitants.
Being freshly rebuilt, it’s possible it burns a tad more oil due to fresh honing. The carb setting were also off being too lean, resulting in a very slow warm up which meant over use of the choke (an enrichenimg circuit on mk2 Amal’s) subsequently making it too rich.During the time spent sorting the carbs, on 4 occasions I was side swiped by duff plugs. The first time it happened I assumed a faulty plug.
By the third time, even I was thinking there might be a link here. I changed to fancy Bosch plugs, and one failed. I’m talking 4 plugs failures inside 50 miles. Each time being certain that the plugs MUST be fine because they’re NEW. Very irksome!So, long story short, I reverted to standard issue Champion plugs, of the type I’ve not used for years. I’ve done nearly 200 miles on these so far (when the weather allows) and they’re running perfectly.Then by coincidence, I read in this months Classic Bike Guide (see pic below) about how modern plugs are designed for clean modern engines and how these ‘Brisk’ plugs are designed for ‘classic’ engines. I’ve not tried any yet, but probably will do so.SO:Is this a common finding amongst you fine fellows?Do ‘exotic’ plugs foul more easily?Have I simply learnt what you knew all along?Has anyone tried ‘Brisk’ plugs?Should we emit spark plugs altogether and run diesel?Here’s the piece about Brisk plugs.
Over 2 years ago I bought a pair of expensive Iridium plugs for my commando' I put them in for the south island rally down to Dunedin in which I covered 3145 miles. On the way back up the lower North Island, the bloody things became lazy, causing backfiring at light throttle on th overrun. This in the past has caused broken throttle slides so I changed them out for a pair of N7Y plugs. When I got home I sandblasted them and put them aside.
I put them back in fro that trip last week to Akaroa and they went well, but the bike became harder to start, the further I went. I persevered and made it back to Mangawhai where I took them out and scraped a carbon build up from them.
After putting them back in, the bike started first kick again. Next day i rode home. Unloaded all my gear then had a rest. 2 hours later i decided to change the engine oil etc but because it had been sitting, attempted to start it again to make sure most of the oil was in the tank.
It would not start, so i shoved 2 new BP6EY plugs in, and it started first kick.In Conclusion, I would never by Iridium plugs for this bike again. I will stick to the BP6EY or N9Y plugs for the local running I do and put in N7Y plugs for the long trips.Dereck. I use Denso Iridium IW27 as a race plug and am happy with them, with IW22s in a 750 V twin road bike.But I am equally convinced that Iridium is not needed in a road bike with standard plugs working well.Unfortunately, NGK suffers from their popularity, meaning they are the most lucrative to counterfeit!Brisk is OEM on Czech bikes, so no surprise really that plugs work well in what they are designed for, I learn't whilst riding in the US that Harley plugs work best in Harley bikes!Worth a try! But I have gained the impression on here that Champion have upped their game over the crap they sold for a few years. I still like the old Champ N4G plugs.
Easy starting and rarely fouling. Someone smarter than I postulated their anti-fouling aspect is due to the heat range (4) which would be much too hot in a conventional plug, but the gold wire electrode stays clean without any risk of holing a piston or other too-hot problems.Just looked at another box of 10 on fleabay for $2.75 per plug. What decent plug DOESN'T cost that much? Would a hotter-range NGK Iridium do the same thing?Edit: just bought a box of 10 for $26.50 shipped. Yup, lead not only makes plugs look familiar, also provides other enhancements. I run a high compression Combat, so the addition of the 25% race gas gives performance a little kick.
Oil Fouling Plug
Fouled plugs can be a real drag, sometimes making you scratch your head in wonder of why. Yes 114oct gas is costly but a can lasts me quite a while, since I started using it no more of the issues similar to what discribed above, makes sense for me, maybe not for everyone. I too have been recipient of knock off plugs and that just plain maddening. Hi octane fuel has a little less energy per unit than low octane.If you need it to prevent detonation, by all means it's a good choice.114 Octane doesn't add performance, just the opposite. The added Octane slows the burn to prevent detonation.You only need enough Octane to stop detonation.It will help keep the engine together if you are running extremely high compression, like 12 to one.I've just recently switched back to Champions as all of my eBay NGKs were fakes.The NGKs purchased at Napa appear to be genuine, however I believe starting is a bit easier with Champions.Glen.