| Author | Message | ||
     Dcmortalcoil |
I've been researching on the internet to see what plugs are equivalent to HD's 10R12A spark plug that came stock in XB9S/R. I found in Denso's Japanese website (http://www.denso.co.jp/PLUG/data/other/1019/01.html) that HD's 10R12A is equivalent to Denso's iridium plug IXU24, which is cross-referenced to NGK's DCPR8E. I've been reading in Badweb different temperature settings than the ones identified above. I've seen cross-reference to both Denso's IXU22 (hotter plug) and IXU27 (colder plug) and NGK's DPR7EA (hotter) & DPR9EA (colder). So I am confused. Does anyone know for sure what temperature range spark plug is suitable for normal (everyday, non-race) riding? In this regard, if the engine is running hot (as indicated by the cooling fan running constantly), can it be caused by a hotter running spark plug? That sounds logical, but my understanding (from Denso's temperature selection disclosure) is that a colder spark plug can transfer heat faster to the engine casing than a hotter spark plug. If that is the case, then the engine case should get hotter since it is absorbing heat faster. So the engine would appear running hotter even though the engine oil would stay cooler due to faster heat transfer to the engine casing. Conversely, if a hotter plug is used, the engine casing would stay cooler (although the engine oil would run hotter) and thus less likely for the cooling fan to turn on. Is my understanding correct? Anyone know for sure what's what? | ||
| Daves |
I'd be looking for the reason your fan is running all the time with the stock plugs first. Ride to the edge! Dave Iowa HD/Buell (Buell Cycle Center) | ||
| Court |
>>>Anyone know for sure what's what? Yeah, but I don't have it with me and I have class until 9:30. If you can be patient for a day or so, I'll get it to you. Court | ||
| Fullpower |
i think some engineer types put their heads together and came up with the 10R12A as the stock spark plug for the XB series bikes. if you are running stock compression, these should work pretty well for you. if you conduct a widespread public opinion poll, and do lots of cross referance sifting, you may well come up with a satisfactory replacement for the $2.55 spark plug, that the factory put in there to start with. good luck in your quest and do keep us posted. regards, dean | ||
| Court |
Lyle, In chatting with a pal I'd suggest that you are correct about heat range being a measure of heat transfer, but it will not significantly change overall engine temperature. What you will change (by changing heat range) is combustion chamber temperatures. Make it higher (hotter plug) and you will have pinging and pre-ignition. Make it too cold and you will have carbon build up in the chamber and possibly plug fouling. Changing plug heat ranges is not going to noticeably change the heat you feel from the bike. There is really only one correct heat range for any given engine configuration. If you change things like compression ratio, you may need to change plug heat ranges, otherwise leave it alone. The motor is your bike is AIR COOLED, so the one thing you need to keep it cool is AIR FLOW. The fan on your bike is running because the temperature has reached the point programmed into the ECM where it turns on, the time to worry, is when it does NOT come on. If the motor is getting too hot, the ECM will let you know by reducing power and skipping spark events. The fan and scoops are designed is such a way that you could (but I wouldn't reccoomend,due to stress on the motor) let the bike idle for as long as you like without moving. The fan will come on, and cool the engine (in time) to a point that it will go back off. The oil has really very little cooling effect in the grand scheme of things. I believe you said your bike is fairly low mileage. These motors don't really loosen up until around 4000 miles, so friction heating will be slightly higher until then. This is also the point where they begin to make their best horsepower due to lower friction loses. Any Dyno measures before then are something of a waste of time and money since true numbers will not be realized until full break in or friction normalization is achieved. Hope that helps a bit, Court |
