roger 04 rt Posted June 2, 2015 Share Posted June 2, 2015 I'm in the middle of figuring out some issues related to my twin-spark lower spark plugs. ( Lower Plug Starting Issue ). While I work that out, I've been wondering what plugs other riders have been running in the lower plug position. I have used: Bosch YR6 LDE Autolite 4164 I don't see a lot of choices for a hotter heat range except Iridium plugs. What are you using? RB Link to comment
waynerd Posted June 2, 2015 Share Posted June 2, 2015 My bike came with Bosch YR6LDE plugs for the lowers (second owner - 14K miles). When I pulled them at the service interval they came out pretty black and gunked up. I think mainly because of availability, I installed the Autolite 4164 plugs (shaved down a socket for install & removal). They seemed to come out reasonably cleaner at subsequent service intervals. At 42K I put in some Denso IXU22 plugs (iridium) - mainly because I found them for a low price and they helped get me free shipping with an online parts order. When I pulled everything apart for the top end rebuild, they looked about as clean as the Autolites. Other things I've read about secondary plug options: 1. NGK DCPR8EKC are listed alongside the Bosch YR6LDE in the manuals 2. I saw a post where a guy switched to NGK DCPR6-EIX (iridium) and was pleased with the results (compared to the standard Bosch YR6LDE and NGK DCPR8EKC). Got all those part number straight? Link to comment
roger 04 rt Posted June 2, 2015 Author Share Posted June 2, 2015 I'm running a richer mixture than stock all the time. My plugs are coming out pretty dark. Your ngk 6s are two heat ranges hotter than stock. I may give them a try. Link to comment
waynerd Posted June 3, 2015 Share Posted June 3, 2015 Hey Roger, I absolutely cannot take credit for the NGK-6 plug idea. I scabbed it off THIS OLD THREAD. Look for the contribution from "jm1515". Also of interest, he notes that, "the Bosch 6-range is equiv to the NGK 6-range". I don't know if that's true, but kinda contradicts your observation. Just the messenger - you can duke it out with him if he's still active on this board (though it would be good to know the correct answer). Good luck. I know you are meticulous with your follow-ups, so it will be good to hear your findings. Link to comment
JamesW Posted June 3, 2015 Share Posted June 3, 2015 I have been using DCPR6 plugs in the 1150 for a couple years after trying the NGK-7 plugs which were somewhat better than stock. The NGK-6 plugs still run darker than the primary 3922 units but are much improved from original heat range and don't foul. Link to comment
roger 04 rt Posted June 3, 2015 Author Share Posted June 3, 2015 Other sources say that the 6e is two heat ranges hotter. Yr6lde shows as being the equal of dcpr6ekc. But the autolite 4164 overlaps some. Hard to figure. Link to comment
Stan Walker Posted June 3, 2015 Share Posted June 3, 2015 It's interesting that having twice as many spark plugs leads to four times as many problems....... Perhaps there is some mathematical principle related to this.....? Just saying..... Stan Link to comment
roger 04 rt Posted June 3, 2015 Author Share Posted June 3, 2015 It's interesting that having twice as many spark plugs leads to four times as many problems....... Perhaps there is some mathematical principle related to this.....? Just saying..... Stan It certainly led to a lot of differences: different plugs, different spark advance curve, different dwell times for the stick coils and even the twin-spark machines vary. Some have a second relay and some don't, which leads me to my next project, to add the 2nd Load Relay so that the ignition coils don't run through the key switch. I think that will be an improvement, especially when starting. Link to comment
VoipWizard Posted June 4, 2015 Share Posted June 4, 2015 It's interesting that having twice as many spark plugs leads to four times as many problems....... Perhaps there is some mathematical principle related to this.....? Just saying..... Stan It certainly led to a lot of differences: different plugs, different spark advance curve, different dwell times for the stick coils and even the twin-spark machines vary. Some have a second relay and some don't, which leads me to my next project, to add the 2nd Load Relay so that the ignition coils don't run through the key switch. I think that will be an improvement, especially when starting. The guys at the CB750c forum heavily suggest to feed the coils thru a relay instead of the ignition key. The reason is the weak electrical system on the Hondas of that era. Makes sense... Link to comment
roger 04 rt Posted June 4, 2015 Author Share Posted June 4, 2015 It's interesting that having twice as many spark plugs leads to four times as many problems....... Perhaps there is some mathematical principle related to this.....? Just saying..... Stan It certainly led to a lot of differences: different plugs, different spark advance curve, different dwell times for the stick coils and even the twin-spark machines vary. Some have a second relay and some don't, which leads me to my next project, to add the 2nd Load Relay so that the ignition coils don't run through the key switch. I think that will be an improvement, especially when starting. The guys at the CB750c forum heavily suggest to feed the coils thru a relay instead of the ignition key. The reason is the weak electrical system on the Hondas of that era. Makes sense... BMW went to the expense and complexity of adding a relay to later dual-spark 1150s so that the stick coils weren't drawing their currents through the key switch. They must have learned something important from the first run of twin-spark bikes with all three coils connected to the switch. During the dwell period, the current through each coil is amps, and there are three coils. I measured a significant drop at the key (below) with my lc-1 drawing a few amps. The peak voltage drop across the key switch could be quite high. I'm thinking about the best way to add the new wiring. ... In addition to the stick coils, I had been running my LC-1 from the key switch. The drop is a few tenths of a volt across my key at times. I've moved the LC-1 to a relay switched circuit. For short times, the current could easily be 5 amps times per stick. I don't have an oscilloscope but based on the steady drop across the key, 10 amp peaks could easily add another volt of drop during the coil on time. I plan to add the relay. It would be great if someone with an R1150 with twin-spark and coil relay, and GS-911 could log a test ride to see if BMW changed the dwell on later r1150s. RB Link to comment
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