| Author | Message | ||
     Bob_thompson |
I always thought I could read plugs fairly well but after reading some threads about A/F ratio readings I wonder. I have always thought to seek a light tan coloration after a run and shutting down properly but you guys with A/F meters are seeing a somewhat rich (12-12.5) readings it seems with that color. I believe 13.0 is about prime but what color are you guys with the meters seeing in that range? I know its probably better to err on the rich side. My M2 after jetting with exhaust and intake modes seems to pull strong all the way through the RPM range without any glitches but I'm seeing very light plugs yet(NGK, DCPR8E's), almost pure white. No intake leaks or fuel problems at all. What do you all think especially you guys with the A/F meters and dyno time? Go richer for summer engine heat or go by how strong the bike pulls now? Thanks much, Bob T. | ||
| Bomber |
Bob . . . being of a similar age, and having learned many of my mech lessons during the days of carbs, points, dwell meters and coils, I find that my plug reading skills on newer bikes seem off . . .. I'm told that electronic ignitions leave far fewer clues on the plugs . . . specific answers to your questions would help a lot of, ehem, experienced folks, and I look forward to them | ||
| Fullpower |
its the fuel guys. this new unleaded reformed stuff does not leave much deposit at all. want color on your plugs? get a jug of 100 LL aviation gasoline. it has a small bit of lead, it is 100 octane, smells like the good old days. i like to blend it with pump gas. dont recommend it if you have an O2 sensor, i think it can foul the sensor. | ||
| Careyj |
Well I have had my carb and plugs in and out of my bike a couple of hundred times, too rich, too lean till I had it dyno tuned with a sniffer, the guy who did it is a master Harley tech with 20 plus years exp. and he said a A/F ratio of 14 is prime for a XL motor. I run ported Lightning heads, port matched intake, CV40 carb, 170 main, 42 pilot, Thunderslide kit w/ clip on needle in middle, Force intake and exhaust and .536 lift cams and got 82hp and 85ft/lb at the rear wheel and my plugs tan on top and black on the ring. It flew threw emmisions and as far as summer a little fatter jetting is better. | ||
| Captainkirk |
Fullpower, Watch it...100 LL (LowLead) AvGas actually has about FOUR TIMES as much tetraethyl lead as the leaded premium we used to run back in the '70s. The Low Lead designation is in comparison to the Avgas used in WWII fighters; 115/130 octane (green in color), and 130/145 octane (purple in color), both no longer available commercially, to my knowledge. My point...yes, there's lead in the gas...a lot more than these motors were designed to run on. One tank or so probably won't cause any problems, but systematic use may cause excess leading of the valve stems and plugs (especially if you're running the new colder 10R12's)and will definitely contaminate your engine oil much more quickly. As to how the aromatics in the fuel may affect your carb, fuel systems, O2 sensor...who knows? My point here is, be careful. Things are not always as they appear. I once ran a tankfull of 100LL through my '77 AMC Matador wagon and ended up doing a carb rebuild because the fuel saturated the float, and gave me a heavy float condition, which caused the engine to surge like a S.O.B. at idle. Live and learn.  Bob, FYI I think 14:1 is the "correct" stoichiometric fuel/air ratio. I also believe the guys are right regarding the color of the deposits and the newer gasolines, though the last time I changed plugs (from the 6R12's to the 10R12's) they were a pleasing tan color......  | ||
| Bob_thompson |
Thanks guys, Maybe plug coloration is still fine enough to have an engine running completely acceptable. Still, with that said I might just look into getting an A/F ratio meter just to complete my super tuning capabilities. BobT. |
