Fish Scale Secondary Clutch Adjustment

[yamahappy]

My new to me stock Viper 03 ER runs great on the trails an on the flat hardpack.
But if I’m on a long grade or in a few inches of fluff I’m fine till about 60-65 then my rate of acceleration drops way off until I work my way up to about 90 and she starts getting happy again. Carbs and Power Vales are spotless and carefully adjusted to stock. Plugs look good and the track is properly adjusted and the belt is new (dayco ultimax 3)
On my old Exciter II, I beat this same issue by buying a new OEM secondary spring and setting it the sheave break-away tension to 15 lbs using a fish scale.
If any one has any wisdom about spring change or adjustments or if you think I’m way off here I appreciate any suggestions.
FYI I’m about 250 lbs / sled has about 1600 mi

 

[sockeyerun]

Do you know what degrees your secondary spring is set at? 70deg. is stock might try 80deg..Soc

 

[yamahappy]

Thank you for the response.
Im gonna guess you're thinking I might be on the right track with the diagnosis. I also failed to mention is that the problem be came more obvious when I took it from 500 to 1800 feet ASL.
Is 60 the stock twist?

 

[yamahappy]

a tad more twist (6+2 /18.5 lbs on the scale) plus basic clutch cleaning (prime and sec) yielded 8600@110 on the dream-o-meter with just a little more to give.

Great Ride!