SPARK PLUGS

[Rick Allen]

Read at one time that NGK XR4 (5858) plugs would be good choice for a '64 R2 with stock ignition, anyone can confirm that?,,,

[Gunslinger]

I looked at a crossover chart and the XR4 is equivalent to a Champion RJ14YC…I think that’s a bit too hot.  The XR5 is closer to the proper heat range but crossover charts can be inaccurate when it comes to heat ranges.  

[ronmanfredi]

More than one Avanti performance shop recommend Autolite AP85 Platinum spark plugs for an R2.  That's what I run in mine.