Iridium plugs

Used them for years, they do not need the gap setting, if you have set the gap they are trout!. I also use a Boyer MK3 system as well. Also, the plugs are surpressed so you don't need to use supressed caps, this may help the running. Starting should be doddle, whereas in the past it would kickback or splutter it starts a whole lot easier with them.

Never had any problems with the recommended Champion plugs.

Next thing riders will be shedding their primary chains for belts, not so easily fixed at the roadside when they break!

Have fitted Iridium plugs to a 72 750. First run out one plug broke down when the engine was cold once she had warmed up (3 miles or more) she kicked back in again and run fine. Assuming a bad plug i replaced it (both actually after getting them replaced foc) The bike didnt run/ tickover/start as it did with my NGK7 plugs. These are supposed to be the all singing all dancing plugs. The one's i used are BPR7EIX which according to the chart are the correct type. Has anyone any idea's. In the meantime i going back to my trusty old NGK's. Thanks Mark.

My suggestion is contact Tim Green at Green Spark plugs he will put you on the right track and he will recommend the correct spark plugs for your machine, I found that using Bosch 3 point electrodes are better than the standard type plugs as the spark is more exposed to the fuel , and these plug are self shielding and burn cleaner , I am get a better MPG now than I did before, using NKG B7ES or Champion N5C , Now I am Using Bosch W7DTC , and the bike Starts first time even after a month standing in the workshop, so there must be something better in this type of spark plug, yours Anna J Dixon

My Commando's plugs- THEY'RE JUST CHAMPION!

Actually Mark, I'm a big fan of the new Avon tyres but you canstick Ethanol where the monkey keeps his nuts.

You mention bad starting and kick back. My Mk 3 (Yes disc brakes all round) used to kick back and be a bugger to kick start, even after draining the sump. Found out my 14 Ah gelbattery of 2007 vintage had expired. After standing 3 weeks without draining the sump but with new battery fitted she almost fired first kick but did so 3rd kick.

Like you I have the Mk 3 Boyer fitted since 1989 and it needs at least 12 volts but the more the better. The plugs may have been a side track but as I say, there's nowt wrong with Champion! Never had one fail yet.......

I'm not sure that you can take much notice of 'recommended' plug grades on a 40 year old bike, unless you are entirely confident that your fuel and ignition systems are up to scratch. Before I replaced the monoblocs on my dommi, it never ran right on the supposedly correct plug as the slides were so worn it was effectively 'on choke' all the time. A hotter plug grade improved things immensely. If I were you I would consider the condition of tune before buying any more plugs. A plug chop should tell you the current state of tune and inform your decision regarding which grade of plug you require. Never had a problem with NGKs by the way, although as with any make you can get the occasional rogue one from new.

On My Commando I use Bosch platinum 2 plugs I found in Walmart while on holiday in the USA. They are probably for a lawnmower as they come in sets of two. They work well and eliminate that occasional misfire and fluff at very low revs thay is particularly annoying pulling away. Platinum plugs seem to have been replaced by Iridium and I use these on my Rotary to good effect.

Thanks. I fitted them from the box, i didnt even think to check gaps. I have a boyer 3 but do have supressed caps.

The MK3 Boyer does not need surpressed caps, you also added a further resistance as all Iridium plugs are resisitor plugs. Drop the resistor caps and you should find they run better, I runBPR7EIX without resistor caps with a digital Boyer and it works fine, a digital Boyer does need a resistor either in the cap or the plug to protect the box from stray signals but not both.

I have never used anything other than Champion plugs in my Fastback. My experience of iridium plugs in my other machines is mixed. My TL1000R runs extremely well on them; however when fitted in my FZR1000 Genesis they were excellent for about 7 miles and then began to foul, so I went back to the recommended standard NGK plugs.

I tried them and had exactly the same problem - I put them in when I installed new coils, new pazon igntion, HT leads, caps, and rewired the lot etc.

I thought I'd totally cocked it up!

Erm, embarrasingly, I contacted Pazon and asked them why their ignition did not work. They were wonderful actually and very supportive, helping me work through the issue - and in fact their ignition doesn't half work well!!

Anyway, I stood there contemplating, because a last desperate swap over of the plugs over did not make a whole heap of difference; then I thought I'll just pop the old plugs in and see what happens, can't hurt.

AND, up it came first kick, running beutifully, strong throttle response no smoke, perfect tickover etc,

You just don't expect two brand new plugs to intermittently fail at the same time.

Iridium plugs? Garbage. You can stick 'em where the sun doesn't shine!!

Iridium plugs are well proven in auto applications. The first time I looked at one I said 'At last'. Back in the 70's 2-stroke racing plugs often feature a fine pointed electrode, which is the perfect shape for something you want to make sparks with. Trouble back then was fast erosion of the point. Gold Palladium, Iridium etc allow for the optimal electrode design to have a long life. Lots of modern cars have them in and specify design life of 20 000 miles and up. I use them in any bike that I am able to get them for.

I remember having three earth electrode in my audis in the 80's. The reason for the multiple earths was to prolong gap life in the face of increased output from transistorised ignitions. The trouble with them is they obscure the spark from the mixture. They are basically an obsolete design.

I would guess that people having bad experience with the newer plugs may be having trouble with getting the heat grade right?

Greetings,

I have run these plugs for some time with NO iisues. My Commando Interstate MkIIA has peashooters,no exhaust ballance pipe, a MkII air cleaner.and stock concentrics. Tri-Spark ignition with digital coil and NGK caps. Starts first or second kick (now that's torn it!).Also runthe same BPR7EIX in my SR500; and that's just returned from the VJMC national rally here in South Australia, again starting first or second kick even when hot.Best thing I ever did was ditch the Boyer on the Norton, they are curent hogs!So not sure what's going down here?

Rgds Steve

Nothing wrong with Boyer, Steve, even old ones, as long as you have a good battery and charging system. (Like we should have)

Previously mark_chapman2 wrote:

Have fitted Iridium plugs to a 72 750. First run out one plug broke down when the engine was cold once she had warmed up (3 miles or more) she kicked back in again and run fine. Assuming a bad plug i replaced it (both actually after getting them replaced foc) The bike didnt run/ tickover/start as it did with my NGK7 plugs. These are supposed to be the all singing all dancing plugs. The one's i used are BPR7EIX which according to the chart are the correct type. Has anyone any idea's. In the meantime i going back to my trusty old NGK's. Thanks Mark.

I have always used NGK plugs in my 1961 Model 50 including the Iridium type which is fitted at the moment. It is one grade too cold but performs okay and the machine will return over 100 mpg on a long run. Starting and tickover are fine.

Al Osborn told me recently that he had the iridium tip come out once in his Reliant Kitten car and put him off using them - it probably did an on the move decoke for him!