Since I’m running the 10.1 piston would anyone recommend running a colder plug. Currently I have a NGK BPR5 wondering if going to the 6 is better for the engine? Just a thought guys

 

Stock heat range is fine. Street ridden bikes seldom see any need for changing the heat range. In any case I assume that you have changed the camshaft as well. So the corrected compression (which is the important compression value) may be same or even less than a stock motor.

 

You ought to be able to read your plugs after 1000 miles. A really good reader could diagnose at 500, but it takes me a while to really understand what the plug is telling me. Don’t jump until you know what the issue you want to resolve is, then correct gap, plug, or map.

 

I just realized the BPR5ES-11 plug comes gapped at 0.44 thou so I guess I’ll pull the plugs are regap at 0.40

 

Btw it’s running fine just diving deep into tuning

 

smart move, gap first, the ride, then analyze.

 

The BPR5ES-11 is one of the best plugs for a modified Evo, the Autolite is also very good.. Gap to .038" for 10:1 comp and the EV 46. What jets you running in the S&S E?

 

For plug gap I run hard all the way to 5th gear at around 5,800-6,000 rpm. If the motor did not cut out… I widen the gap until it does cut out.. then I close the gap 2-3 degrees and retest for no cutting out. I run between 50 & 55 thou gap on the soft tail and 48-50 on the Road king.

I test coils this way as well. After thousands and thousands of dollars spent on industry hyped ignitions I truly believe the Dyna S with a 90 OEM coil from Harley is the hottest fatest spark you can have under a consistant load. Oddly I only have it in the Shovel. I’m running the 2000i in the EVO’s with a quality 90’s style three post coil.

 

The jetting I haven’t touched, its what came in it from S&S.