Well,
the P650 needed the valves adjusted, & when it was done I put the Diamond G snorkle on, Twin Air filter in, & 142 jet in front, 145 in rear, turned the mix screws out 1/2 turn..
this has been the best 77$ I have spent..(I'll probally say that about the black spring when I put it in as well, but 25 bux or so..
it really makes a big diffrence in the bottom end, mid & top is crisp..but it dosen't affect any of the slow speed use I do..it puts a smile on your face for sure..

 

Wait till you get the spring you will say that it changes your take off it is ggggrrreeeeeaaatttt!!!

 

Monte,
I probayally will say that, I have the red spring for the drive, & the black spring for the driven, but have not got around to putting them in yet. a lot of my use (97%) is going slow, taking shots, & moving equipment from place to place, but just becuase something weighs 600 lbs, that is no reason not to let it perform, now I can enjoy going out & picking up equipment more..(& a ocassional trail ride..)

so probally the best mods are tires, black spring, carb jets, air filter, & snorkle..

I put sur tracks on..what a big diffrence over the stock rubber...

I need to be able to pick my way slow at times, & romp on it at other times..

 

Surveyor, were those factory Kawi jets then?

 

mort,
Stock jets..all you need is the 145 if the quad was jetted 138/142 from factory, mine was..
I just swapped out the rear (142) put it in the front, then put a 145 in the rear..real happy for 6 bucks..
turn the screws out 1/2 to 3/4 turn..from stock setting..mine were 2 1/4 stock..now about 3...

now temperature 30 degrees change (it is about 85-90 degrees here, ) about sea level as well.. a jet size smaller for each 2000' increase in elev, and jet size larger for each 30 degree decrease in temp..(roughly)

hope this helps..