yeah, when I bought mine the teenage kid behind the counter claimed they would improve my fuel economy, I never really noticed it. I think they just last longer and that's fine with me.
Spark plug experimentation...
- Thread starter The Dark Shadow
- Start date
Iridium has a very high menting point. Its a very hard metal and resists wear. the tip design concentrates the spark. The lack of wear, the concentrated spark make emissions and spark consistant over the life of the plug.
just grabbing different plugs for the test is just not accurate. A racing spark plug is not designed for that purpose. Are all the plugs different heat ranges or the same. The first
NGK plug he tested is not for that engine. If he used a hotter plug that performed better will it burn up a valve over a long period of time? it's cute but need to be tested over many hours and miles. Yes when you first put an iridium plugs in your bike it performs better, it's probably because your old plugs were degrading. Now has anyone tried snake oil?
just grabbing different plugs for the test is just not accurate. A racing spark plug is not designed for that purpose. Are all the plugs different heat ranges or the same. The first
NGK plug he tested is not for that engine. If he used a hotter plug that performed better will it burn up a valve over a long period of time? it's cute but need to be tested over many hours and miles. Yes when you first put an iridium plugs in your bike it performs better, it's probably because your old plugs were degrading. Now has anyone tried snake oil?
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No. The engine doesn't run hotter, only the tip of the plug has a longer thermal pathway to the cylinder head.
woodybelle
Site Supporter
I found. this on the NGK webiste:
INDEXING
Indexing is done by placing (usually copper) washers of varying thickness on the spark plug shoulder, so that when the spark plug is tightened, the plug will rotate a certain amount, and gap will point in the desired direction. In most engines, performance will improve when the spark plug gap opens toward the intake valve(s). However, without testing different index positions in an engine on a dyno, it is nearly impossible to determine which index increases performance. Indexing spark plugs will typically make only a few more horsepower – usually less than 1% of total engine output. For a 500 hp engine, that’s only 5 hp. It is usually not worth the effort.
There are also drawbacks to indexing spark plugs. When washers are added, the spark plug may loosen if the washers don’t crush properly and hold the torque. Also, if too many washers are added, the firing end of the plug will not be as far into the combustion chamber and performance can decrease.
INDEXING
Indexing is done by placing (usually copper) washers of varying thickness on the spark plug shoulder, so that when the spark plug is tightened, the plug will rotate a certain amount, and gap will point in the desired direction. In most engines, performance will improve when the spark plug gap opens toward the intake valve(s). However, without testing different index positions in an engine on a dyno, it is nearly impossible to determine which index increases performance. Indexing spark plugs will typically make only a few more horsepower – usually less than 1% of total engine output. For a 500 hp engine, that’s only 5 hp. It is usually not worth the effort.
There are also drawbacks to indexing spark plugs. When washers are added, the spark plug may loosen if the washers don’t crush properly and hold the torque. Also, if too many washers are added, the firing end of the plug will not be as far into the combustion chamber and performance can decrease.
OP
OP
Thanks for this. What is stated is logical to this analytical brain of mine.
You mark the base of the plug and move the plug to a different cylinder if needed. You have about 90-120 degrees to play with. never used washers.
So I guessed this one correctly. 
from giggle about using a hotter spark plug The most serious result of selecting a heat range that is too hot is overheating. Overheating will cause the electrodes to wear quickly and can lead to pre-ignition. Pre-ignition occurs when the air-fuel mixture is ignited by a hot object/area in the combustion chamber before the timed spark event occurs.
Mr.E
Steve
So when I had my FJR1300 I bought a box set of Iridium CR8EIX NGK's but never got round to fitting them.
I note that these are close to the specification for the ST1300 which maybe a "9" ~ so do you folks recon they might be okay to fit?
I'm certainly no whizz on these Sparkling Plug thingies!
I note that these are close to the specification for the ST1300 which maybe a "9" ~ so do you folks recon they might be okay to fit?
I'm certainly no whizz on these Sparkling Plug thingies!
Kevcules
Site Supporter
Do a cross reference to make sure because each different plug has subtle differences from engine to engine.
I use the Iridium in the 8's also
Indexing is evidently somewhat controversial. Look at the discussion below. It is not a sure thing.
I think one way to avoid the problem of the plug loosening would be to use different thickness copper crush washers, and not stacking them. That does not solve the depth issue, but it all may be a moot point and something that will vary from engine design to engine design. Regardless, absent testing a statistically significant number of engines on the same dyno under the same conditions we are back to where we started. Not knowing, but thinking.
I think one way to avoid the problem of the plug loosening would be to use different thickness copper crush washers, and not stacking them. That does not solve the depth issue, but it all may be a moot point and something that will vary from engine design to engine design. Regardless, absent testing a statistically significant number of engines on the same dyno under the same conditions we are back to where we started. Not knowing, but thinking.
We should change this thread to motor oil types