[pat1098]

Originally Posted by ttpete

I'm sticking with the NGK. I've used their plugs for many years on many different bikes. This one is a special configuration for a specific bike (Ducati) and isn't listed for anything else. It exists one heat range colder as an MAR9A-J, and that's for a BMW HP2 Sport, which is also a 4 valve bike.

I suspect the BMW runs a 'colder' plug as they are still air/oil cooled, and therefore more in danger of developing 'hot spots' in the combustion chamber and exhaust port?

[anatra difettosa]

Anyone indexing these plugs...?

[Hawkeye]

Originally Posted by ttpete

I'm sticking with the NGK. I've used their plugs for many years on many different bikes. This one is a special configuration for a specific bike (Ducati) and isn't listed for anything else. It exists one heat range colder as an MAR9A-J, and that's for a BMW HP2 Sport, which is also a 4 valve bike.

Originally Posted by pat1098

I suspect the BMW runs a 'colder' plug as they are still air/oil cooled, and therefore more in danger of developing 'hot spots' in the combustion chamber and exhaust port?

You both got it on backwards. The heat rating of each NGK spark plug is indicated by a number; lower numbers indicate a hotter type, higher numbers indicate a colder type.

http://www.ngksparkplugs.com/tech_su...2.asp?mode=nml

[ttpete]

Originally Posted by Hawkeye

You both got it on backwards. The heat rating of each NGK spark plug is indicated by a number; lower numbers indicate a hotter type, higher numbers indicate a colder type.

Right you are! I knew that, must have been thinking Champion or had a brain fart, one of the two.

[vinman]

In case anyone is interested in using something other than the NGK plugs, I just installed the Denso Iridium IU27 plugs and they work great. I did need to purchase a spark plug socket because it is a different size plug. I got a set of three (husky) from home depot, part #379 438. Unless you already have a thin wall 5/8th or 16mm socket.

[pat1098]

Originally Posted by duc_finder_js

There are also some newer plugs out there called surface gap plugs....RACING PLUGS ONLY. 709/G54 Champions. I have a pair if anyone wants to try them. $30.00

Thanks

Not sure about these being newer - I seem to remember fitting some as standard to a Suzuki Rotary in the '70s.

As to the hotter/colder plugs discussion - of course you are right Hawkeye - in NGK the lower number indicates a hotter plug. I just followed the comment re "colder plug" from previous post. Should have checked...

[ttpete]

Surface gap plugs have been around for many years. I'm thinking some of the Kaw triples also used them. They have no heat range rating.

[Mr Jurassic]

THE DENSO IVE NOTICED is one heat range hotter then the ngk

Also ngk has a iridium that is within exact spec of the denso iridium its a ngk - cr9eix
stock number (3521)

so the regular mar10a-j's are colder , more liable to fowl out and arent irdium.

i looked up threads and everything on the cr9eix's and evrything matches the deno iu27

[vinman]

after riding with the denso iridium IU27 for over 500 miles, I have to say they even improved gas mileage. not much, maybe about three miles per gallon.

[duc_finder_js]

So where can I buy the IU27 Denso Iridiums ?? Do you all recommend these over the NGK's? My bike is getting harder to start - but living in the Mid-West - the weather is so freagin fickle and it's either hot, cold, freezing or burning up! Always a surprise when you walk outside in Mid America!