Cold plugs explained...

[stu]

Here.
http://www.g2ic.com/forums/showthread.php?s=&postid=417680#post417680

This guy was wondering what cold plugs meant, so I tried to expalin it as well as I could. I even drew him a picture as a reference. I thought that you guys might appreciate it if I shared the learning with you; for those of you who were curious. Here is the picture again.

[exciv2000]

uhm, I could be wrong, but I think you reversed it. I think the one on the right is the cold plug. Also, there should be no difference from one to the other regarding the distance between where the spark originates and the strap.

[SleeperZ]

No, Stu has it right. The cold plug has a larger contact area to the body of the plug to conduct heat from the tip faster - it cools off faster (or rather, heats up slower).

[exciv2000]

Oops, I guess you are correct, my bad:
http://www.ngksparkplugs.com/techinfo/spark_plugs/overviewp2.asp

[WagN2NR]

Nice stu! Plugs are on my mine lately...Im gonna go with OEM spec plugs or plugs in the mid range.

[stu]

I didn't mean to draw the gap so big on the cold plug I was in a hurry. :p

[Talus]

The problem that guy had kinda sounds like what happens to my bike.... the engine cuts out above about 5,500rpm, but will run higher at full throttle. I realise the engines are much different (tubo vs. n/a, bigger displacement 4 vs. small displacement twin), but the problem is so similar.
Could it be spark plug application? Fuel? ( I have used 85 octane mostly, but have tried 87 too) or ignition timing? Or maybe my carbs just suck. That's a distinct possibility.
Info on the bike: 1981 Yamaha XS650H 650cc parallel twin, dual sidedraft carbs.
Like these beasts (http://www.650central.com/)
Check the "XS650 tech info" button
under the specs, I'm pretty sure I have a 4N9 engine.

[Talus]

Okay, that last post lead me on a lot of searching and I ran across a good diagram. Better than Stu's paint creation (gasp! hard to believe, I know)