Platinum plugs

[2wheelfun]

I never read anyone posting about using them. On cars I think they're the greatest thing since AC was introduced. They last 100k or longer on cars, that should mean 1 plug change on a scoot then fergetaboutit. What's the advantage of iridium plugs?

[de dee]

  from past experiance,  I changed the plugs at 300,000 km.  on a toyota van and they looked like new after I cleaned them, I have 40,000 km. on my plugs in a 300i downtown, checked them and they still look like new,  I say they are well worth the money,. one question is it spring yet?haaaaa

[Stig / Major Tom]

Don't know about platinum....but my iridium plug is the best $7 I've spent on my scooter.
Stig

[wkreps]

I know this has certainly been hashed out in another thread but since we are on the topic, what are the advantages of an iridium plug?

[BettinANDlosing]

Platinum plugs are a step harder metal than copper plugs, but iridium is the hardest material you can get for common plugs. Platinum lasts about half as long has iridium. IMHO platinum is not as cost effective as iridium, they aren't even a dollar cheaper for the NGK so you might as well get top shelf and go with iridium. I want to make it clear, you don't get more spark, hotter spark, or higher voltage with any of these plugs, the only difference is the tip size. Iridium has a very fine point tip, that focuses the spark energy. Platinum has a slightly broader tip that iridium, and everyone has seen the copper tip. In my experience it's not worth going with an expensive plug if your machine isn't running right, the smaller tip of the iridium plug will foul easier and if it's running hot I've seen it deform. For any fuel injected bike either of these plugs will be a good plug upgrade, but the iridium is more cost effective. Another thing to mention, copper is actually MORE conductive than iridium or platinum, its actually one of the best conductors in existence. Its just soft, so it gets worn out faster. You will get the most spark energy transferred from the coil to the combustion chamber with non-resistor copper plugs.

http://www.engineeringtoolbox.com/melting-temperature-metals-d_860.html
This is kinda a cool chart, iridium melting point is more than 2x higher than copper.

[wkreps]

Not wanting to taker this off topic but . . .
So with that chart it shows:

Aluminum Alloy 463 - 671C / 865 - 1240F

Why do so many say not to take your cylinder head temps (CHT) above 375 - 400F. Given the numbers above are to a liquid state but  less then half the low end melting temp seems excessive. Just asking cause my scoot CHT can get to 400 pretty quickly at wide open throttle (WOT).

[BettinANDlosing]

Not wanting to taker this off topic but . . .
So with that chart it shows:

Aluminum Alloy 463 - 671C / 865 - 1240F

Why do so many say not to take your cylinder head temps (CHT) above 375 - 400F. Given the numbers above are to a liquid state but  less then half the low end melting temp seems excessive. Just asking cause my scoot CHT can get to 400 pretty quickly at wide open throttle (WOT).

That's just the safety zone. I've had Vespa guys with 200+cc kitted monster vespas say their CHT was at about 1000 for a short time, exhaust was glowing red LOL. The danger is not melting, the danger is the piston getting so hot that the STEEL rings seize in the piston. Or that the piston expands more than the cyinder and seize into the bore.

[mrbios]

I don't recommend anything except the stock NGK spark plugs as they work great and you gain nothing form any other plug.  That's all I have run in my GV250 for the last 13K miles.  Start perfect and runs great.  Worry about other things on your scoot like actually using it so the gas doesn't go bad or add gas stabilizer if it sits a lot or over the winter. Spend money and effort on things that matter vs replacing parts the do their job perfectly same with oil - use the cheapest but change it every 1200 miles and at least once a year. Pe@ce out.