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I get people over several winters asking me this question about 990’s vs 965.
I made a “canned speech” so I can cut-n-paste it into my emails when this question arises.
Figured i’d put it up to read here too…

It looks like your Summit 850 kit works with 990 or 965 ramps installed. Is there any benefits to installing your kit in a clutch with one or the other

HI Robert. Thanks for asking
The difference between the two is the curve of the ramp
The 965 and 990 start out the same [at engagement speed and a little bit] , but immediately say, when the clutch starts to move the sled, the sled starts moving, the 990 roller profile starts to curve lower, meaning, more aggressive.

The 965 is a more quicker rpm ramp. Like a motocross bike when its shifting gears, you know how quick that sounds, more leaning towards that. Quicker revving.
IF you want to make a 990 work similar to a 965, then run the 990 in a higher clicker number.
Aaen tuning law; higher ramp angle contact, less force is transmitted

In essence,[by its nature] raising the clicker for the 990, kind of “stalls the clutch shifting” for a moment, and you get the feeling of a quicker rpm to get to 79~8000 like a 965.

Say you seen/tried a setup with a 965 in clicker #3, and wanted the 990 setup to act like that, then clicker the 990 up to #4 and they will be close, maybe almost not tell the difference between the two.

I cant say benefit, I can only say the difference in conduct between the two.
Pictures attached.