I was looking at the Primary springs on HPD's site, and was wondering what (*55lbs/151 lbs) means? They list a bunch of different clutches with different lbs. ratings. I tried to call them and they are out of town till the 18th.

 

I have the white primary spring in mine and I can know pull a wheelie the k&n filter helped it out quite a bit too.

 

The numbers stand for the amount of pounds it takes to compress the spring first with the clutch
not in motion.Second with the clutch fully engaged.So if your stock spring is a 50/150 and you installed a 75/150 this would increase your initial rpm engagement.If you put a 50/125 you would maintain your original engagement however your shift out rpm's will be lower.