Has anyone tried Iridium type plugs on a K motor, are they beneficial in any way? or are they best avoided on an old K lump, just curious if they help in any way justifying their cost.

D

If you get yourself a pot of petrol and air, squash it to about 10:1 and then throw a match into it, I will guarantee that it will explode. The same will happen if you put a spark from a plug into it. Normal plugs work fine for most of us and the power for the spark at that plug is determines by the voltage in the plug lead. The power output from the engine is determined but the amount of fuel and air in there.
A different plug will make no difference to the bike.

Pity the poor guy with the Mercedes V12. Twin spark. Then he finds the rear cylinders are buried under the bulk head.

So 24 iridium plugs needs a mortgage because only the main dealer will fit all 24 but they are supposed to last 50,000 miles I think.

For the K NGK D7EA seem to be the business for a fraction of the price........and put the rest in the beer fund.

They are useful for V twins with a magneto since they fire at about 5000 volts less than a standard plug.

Now, I wonder who uses a 50º V twin?

Paul.

@sidecar paul wrote:They are useful for V twins with a magneto since they fire at about 5000 volts less than a standard plug.

Now, I wonder who uses a 50º V twin?

Paul.

So does a normal plug with a smaller gap.

@sidecar paul wrote:They are useful for V twins with a magneto since they fire at about 5000 volts less than a standard plug.

Now, I wonder who uses a 50º V twin?

Paul.

Farmer in the field behind me has some Deere traction that uses those 50 degree engines.

I really don't see the need for platinum/iridium/unobtainimum plugs as the NGK D7EAs work very well and last a long time.
I saw a D8EA virtually without an outer electrode and it was still firing because of the CDI ignition where a conventional points/coil ignition would have had no chance bridging that gap.

I use 'm on my two stroke Yamaha RD's - they don't foul when caught in traffic for long periods...and I have to go slow.

Thanks gents food for thought, I have no problems with using NGK's just wondering that's all.

D

A lot of transverse V6 car engines (e.g. Mitsubishi Magna in Oz) use them in the back bank because of their lifespan. You have to remove much of the intake system to change plugs, so with these you don't have to do it as often. They use ordinary plugs on the easily accessible front bank. 

Bill

In the mid 80's in the U.S. EPA regulations came into effect mandating that auto engines run for 100,000 miles without maintenance and still meet fuel economy and emissions requirements.  That meant that items like spark plugs be capable of over 3,000 hours of operation with no degradation in performance.

Rare earth elements like palladium, iridium, and platinum are used to reduce the electrode erosion that causes poor ignition.  I have had cars where the plugs lasted nearly 200,000 miles with no loss of performance. 

Since dealers' business plans relied on tuneups as a major source of cash flow, it should be easy to see why the manufacturers kept the 100,000 mile requirement under wraps for as long as possible.

tried using iridium plugs in both my paiggio mp3 250 and my yam xs 650 , got very few miles (couple of hundred kls ) on both before having to swap back to the original plugs , the xs650 had a rebuilt motor and the mp3 had only 8000 kls on new bike . original rated plugs back in and both running very well still.. don't know why as a lot of people swear by the irridum plugs , but this is my experience ( same as the mp3 seems happier running on standard unleaded petrol rather than ultra where the xs 650 is happy with either )

Had iridium's as standard equipment in my '89 Toyota Corolla that did half a million km's.  I replaced the plugs every 100,000 km's and they looked fine.  Now I'm using them in my Triumph 1050, but have only covered 20,000 km's with them.

For my K, when I eventually get it running one day, it looks like the $2.50 NGK's will be the go!