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PostPosted: Fri May 22, 2009 2:29 pm 
Still on the Trailer Member

Joined: Fri May 22, 2009 2:00 pm
Posts: 2
Just wanted to pass along the results of my personal evaluation of some clutch performance improvements to fellow DS250 owners who might also be looking to get more performance out of their Can-Am DS250.

The following data represents my comparison on a 500 ft drag strip with timing lights between the stock factory clutch calibration, a DIY lightened CVT roller mod, and a performance tuned CVT clutch kit from Full Power Performance (FPP) that incorporates custom springs and roller weights.

After some discussions with other forum members and some R and D, I came up with a simple D.I.Y. mod involving lightening of the CVT clutch roller weights. This mod alone has proven to increase the hill climbing ability of the DS250 greatly over stock.

There isn't a significant improvement in the drag times, but then again with a 17 HP 4-stroke quad you're not ever gonna see a huge 3 second gain, etc...

The lightened rollers pulled more consistent than stock thru shiftout without adversely or negatively affecting top speed. Definite difference is that the engine rev's higher and doesn't knock and rattle under load, as is so noticeably does being lugged stock... now pulling 6600-6700 RPM, up from 5200 RPM stock.

The FPP clutch kit was even better and picked up 1/4 second in 60 ft and over 1/2 second in 500 ft, which I know doesn't sound like much but is pretty significant for a 17HP 450+lb machine. For those who understand ET's, you know this shows that it's accelerating / pulling harder from a dead stop, as indicated by the faster 60 ft times, and therefore at the end with the wide open speeds is equal to a quad length, or two, difference thru the gates...
The FPP kit engagement of the centrifugal clutch was raised closer to peak torque than the stock calibration and provides noticeably stronger take-off.
Shift out occurs at a higher RPM closer to at peak HP, as well. Even with the taller big meat grabbing 22" rear mud lug tires, it will power-brake in the hard packed drive way and actually spin down the test track.

The huge benefits of both the lightened roller mod and the FPP clutch kit come off the track and with enhanced hill climbing ability.
We ran this 250 up a short and steep side hill to the test track from a dead stop at the bottom. In stock form it lugged down to a complete stop right in the middle and stalled the centrifugal clutch (slipped) at 3400 RPM. With the lightened rollers, the 250 actually spun the wheels up the hill at over 4500 RPM (1100 RPM closer to peak torque) and the FPP clutch kit was even quicker at this with it's significantly higher engagement RPM.
Both improvements are definitely snappier and more responsive compared to stock, more fun in the trails and hills, or in the sand, and easier to wheelie or power slide. The optional 14 tooth front sprocket from FPP (to gear down some) improved things even more!

Click on the data chart to enlarge...

Note: This comparison was done on my wifes 2008 DS250 with stock gearing, larger 22" rear tires (taller final gear ratio), stock exhaust and spark arrestor installed, stock airbox & lid with Uni Filter, stock carburetor jetting #105, AICV active, 180 lb rider, temp 72 deg F, 1549 ft elevation.

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