Spark W7DC or ???

[grumpyone]

Morning; We just purchased a R 100 RT That the owners manual calls for the plug W7DC; The bike had in it W5DC but it came from near sea level and we are about 6500 ft. Our R 80 Calls for the same W7DC ; Both bikes have ele ign. so wouldnt both bikes work fine with the Hotter plug??? Why would you go down two temps on the plugs to W5DC ??? When in doubt the owners manual should win. right. ??
Are nkg plugs equal to the bosch plugs or are one superior?
Thanks
Jim and Esther

[88bmwJeff]

Unfortunately, Bosch has stopped making the W7DC, which is a copper core, non-resistor plug. The current plug Bosch is selling as a replacement is a resistor plug; however, the common census is that the resistor plugs should not be used. NGK are good plugs, and many airhead riders recommend them. In fact, Rick at Motorrad Elektrik does as well. If you're are not familiar with him or his products, you should head to his site. From your recent posts, I'm getting the feeling Airheads are new to you. If this is the case, I would purchase Rick's manual on the charging system. It's a good explanation of how the system works, where things typically go wrong, and how to check for them.

Follow the link to Rick's site.
http://www.motoelekt.com/

[grumpyone]

Jeff were not new to airheads had several over the years just not into the mechanics as much til now. The only thing new to us was the fact the bike out of the lower elevation had had w5dc instead of w7dc in it??? We use the nkg in the r 80 that crosses from the w7dc already and are happy with them. We did find a w7dc at napa in town today so guess till next change were good to go.
Thanks
Jim and Esther
about a year ago we ordered some relays from motorelectric and his book while we were at it but evidently the book got forgot and not put down and we had not gotten around to ordering it again. Sounded like a good deal. We already had to replace the wire harness on the r 80 ; :bottle

[Polarbear]

You know the Hotter plug is a plug with less ability to cool itself, via the outer ceramics! They both put out the same spark:). The Airhead as an air cooled motor, should probably need the cooler plug for this reason. Although the fins on the airhead are exceptional heat sinks and eliminate most heat issues. Use the cooler plug:). Many think a hot plug is a hotter spark and this is wrong, as i know it. Happy Trails, Randy"Polarbear"

[jbcollier]

This gets confusing but in Bosch parlance higher numbers are hotter. NGKs are the other way around with lower numbers being hotter.

The W5DC is a colder plug than a W7DC. IMHO, the extra bit of internal resistance of a WR plug will have minimal effect.

[rocketman]

Here is a ling to NGK plugs heat range info and charactoristics of plugs in general and some inof on heat and how its effected by elevation (on page 4 of the link)

NGK PLUG INFO (http://www.ngksparkplugs.com/techinfo/spark_plugs/overviewp2.asp?nav=31000&country=US)

RM

interestin side note here I just went back to NGK BP6ES from having run the 7ES plugs and the bike actually seems to run cooler, I guess that could be because the heat sink propteries of the "hotter" plug are better and I'm getting better/cleaner burn in the combustion chamber(?). I too thought that up was hotter with NGK, interesting to know its the other way around with those.

[krehmkej]

With NGKs I had to go one step colder, BP7ES, for my R80/7. YMMV, however. I have always used NGK with good results. Convenient that this is the same plug used in my XS650.

[The_Veg]

Unfortunately, Bosch has stopped making the W7DC, which is a copper core, non-resistor plug. The current plug Bosch is selling as a replacement is a resistor plug; however, the common census is that the resistor plugs should not be used.

I think that depends on whether or not you have resistor caps, and whether or not you have electronic ignition. If your bike should have a resistor somewhere, I don't think it matters whether it's in the plug or the cap.