This simple "poor man's" trick worked great for me. This procedure is 100% "get er done", and may not suit everyone (rocket scientists stop reading now!), but I'd bet there are plenty of people who would be happy to have a simple, safe, cheap, and VERY effective way to resolve those sagging rpms for very few $$. Just be aware that we are gonna void the warranty here (just as you would if you spent big bucks on an engineered clutch kit).
What we're doing here is drilling an extra hole for the spring in the helix (to add more adjustability to your preload), changing the primary spring, and grinding the back side of the flyweights / levers / centrifugal levers to reduce their effectiveness against the spring.
I will assume the reader is capable of removing and dissasembling both clutches safely.
If you need some "know how", pick up a .pdf copy of the BRP shop manual (note that you may need the shop manual for the XU (Expedition) to get coverage on both the 600 ace and it's clutches). Then surf dootalk forums, there are some great write ups by others with much better pics and technical writing skills than I posess.
If you need tools, C&T powersports makes a great kit that will "doo" it all with the ACE clutches for $100 : http://c-tpowersport...ch_toolkit.html
My sled is a 2012 mxz 600 ace sport. The primary spring I chose was that from the 600 ace tnt models (417223314).
STEP 1: GET SOME BACKSHIFT (ie RPMs during deceleration)
My driven pulley was set from the factory in the tightest preload holes. I had to drill another hole (see pic) so I could add a little more preload "twist" when re-assembling the helix. That brought me up about +4lbs of preload (22 break away, 18 let off = 20 lbs avg as per shop manual method). Remember, when you re-assemble, pick the hole in the cup that will force you to do the biggest preload "twist" to get the arrows to line up before you slide the helix down in. Check your work when your done.
Edited by 89MX, 10 February 2018 - 08:03 PM.