Got a 13 xp. All stock. First changed out the helix to Hunterworks custom angle an less engine braking. Ran awesome like that, pulling all way to 8550 rpm an 80mph. Then installed the dalton clutch kit with primary spring an adjustable weights. Noticed the primary spring is quite a bit longer. Have it set up like they say for heavy 26" tires. Can only get it to rev 8100ish an once over 65 mph drops off an holds 8000 at stays there at 75mph. Have tried even dropping the weights empty (57.35g with the silver rivet still in tip), stock is 59grams. Like that it revs the 8200 but has no pulling power. 0-60mph time went from 8.4s (stock primary an new helix) to over 10seconds like that. I'm thinking the longer primary spring is holding up the primary on me. Anyone have any experience with this???