[ctdls]

I'm starting to think about again, my sled season is winding down 

What I found last season was the shift rpm is quite low even with secondary being re clocked. I was planning to reduce the weight in the front clutch to increase the shift rpm.

It just occurred to me what may happen in low range, I'm sure if I went out right now & planted the throttle in low range I would see a dramatic increase in shift rpm.

So what is the trade off here, if we get it right in Hi range do we ruin low range performance?

Or do we allow a slight over rev low range fro improve Hi range

[NMKawierider]

I actually got an improvement in low range performance going up from B1 to C1 or B2 with the 22g sliders and probably lost a whooping 4mph top end. When I went to A2..I lost another 8mph top end and it wouldn't backshift on hills any more until the speed and RPMs dropped so low I lost any chance of making it...so I went back to B2. It still has some issues on long steep sand.. but ...not in low range. It surprised me in that it would develop enough speed while staying on top of the power curve..enough that I can take my foot out of it. In this vid, its about a 46-47 degree sand hill with two 220lb guys in low range. And I had to back out of the throttle.


Not a valid vimeo URL

[ctdls]

Any idea what  the RPM did with those changes & did you find the happy RPM? I know you have played a lot with these clutches.

[Hrc630]

When I have play with the stock clutch, the best result was B2 + 22 gram. I have play A LOT with the stock clutch before the race kit. If you go below 22 gram and b2, you will overrev the stock powerband.  With an exhaust and more fuel on top you will retain the oem 72 mph top speed an gain in acceleration

[NMKawierider]

I think the goal is to get the RPMs in the "sweet" spot between the max torque and HP bands. I believe the RPMs need to come up about 1800-2100 to do that. Just the 22g sliders pick it up about 500-600 by themselves although C1 gave me better back or upshifting on the flats, it just felt like it was under that optimum power curve..by just a little on any hills. B2 was slightly over it but would settle back into it under loads like hill climbs. A2..well, it was with my setup way past that curve and was over revving all the time... and between the resistance of the spring,load coming back through from the transmission and power from the engine all applying pressure on the helix, it just wouldn't up/back shift up hills. It was like the sliders were glued to the ramps. It would if I let off the throttle and re-hit it..but who does that! It would on the flats but it was way over revving..IMO. I went back to B2 then tried C1 again and watched things a little closer. Ended back at B2 because although the flats were OK with C1, the hills weren't. Here a little vid I did when testing C1 with 22g sliders. Not very scientific, but..at least it's a vid!...lol

 

[NMKawierider]

While on A2 I made this vid. At first it seemed promising but as the day went on, the graphite I use on my helix wore off and problems started showing themselves. Then after a few rides it was clear this wasn't going to work for me. Here's that vid.

[ctdls]

I think the goal is to get the RPMs in the "sweet" spot between the max torque and HP bands.
 

Zaaactly  This is how I set up sleds so the engine is nicely hunting between the two peaks, much easier to find these numbers with a sled.

So far I've seen some different peak rpm numbers advertised for the 800's, not that the displayed rpm means anything. Any idea on the display what the best rpm is, they must have very good torque as the stock calibration has the motor running quite low?

I followed your comments using the clocking chart & everything fit until A2. The angle/degree jump is huge with that number, maybe the driven spring is wound so tight it cannot function consistently. B2 & C1 are close & would make sense fine tuning.

Always enjoy reading you comments NWK, you strive for the consistent repeatable results!

[NMKawierider]

I can't believe some people go farther then A2. Must be something wrong with their springs... or they aren't clocking them correctly.

These CV Tech clutches are supposed to be pretty good but IMO they really need to take some lessons from... well the sled guys for one. They have some clutches..

[Hrc630]

The CvTech are on the sled since a long time.. all BRP guy that need better clutch than OEM use CvTech.

[ctdls]

These CV Tech clutches are supposed to be pretty good but IMO they really need to take some lessons from... well the sled guys for one. They have some clutches..

The checking I did last fall if I remember correctly this driven clutch by CV Tech is proprietary & built for CFMOTO. I did not have much like finding cams & springs, I couldn't believe as big as CFMOTO that there was "no" Hi Altitude calibration 

I did some checking on the HP & Torque numbers, this one is US & Cdn advertised:

Engine Power62 HP @ 6700 RPM
Engine Torque, Maximum53 ft lbs @ 6000 RPM

Was sure I had seen 7000rpm for peak HP somewhere, cannot find that. This rpm range seems like a reasonable window to target, closer to the 6700 

You have larger tires & maybe heavier, so a factor in the clutch set up I'm staying stock.

One more question for you, what elevations are you riding when posted the two vid's?

[ctdls]

The CvTech are on the sled since a long time.. all BRP guy that need better clutch than OEM use CvTech.

I've been Ski Doo 25 years in the mountains, stock, big bores, strokers, NOS, turbo's & probably anything else you can imagine or think of 

As soon as I can remember seeing a CV Tech clutch set up on Ski Doo I will post back

[Hrc630]

Here in Quebec many etec 800 and 1200 run CvTech.

As for the RPM, on the dyno I have my peak at 7300 rpm and the curve only drop dramatically close to the cut off. For me, on a stock machine I try to keep the rpm over 6800 all the time in acceleration. For my machine the rpm jump at 7200 on a start an stay over that all the time. With the autotune on the Power Commander the need in fuel over 7000 clearly need to be augmented. This is one of the reasons why the stock set up won’t reach a good top speed. I have mesures the 0-60 mph in 7.1 sec with the gtech and 78,4 mph on gps. I keep testing to have the maximum of the stock engine. My friends can Am 800 stay at 8000 rpm all the time but I think the cam on the can am are more agressif

[NMKawierider]

One more question for you, what elevations are you riding when posted the two vid's?

The first vid..on the road, was around 7700 - 8000 feet and the second on the desert was between 5400 - 5600.

Yeah the 27" Reapers are a lot heavier then the stock tires....and the 90+lbs extra weight from things like the steel skids, doors,box and other things play a major part.  I've tunes several other clutch setup and have not has such a struggle getting the backshift right under loads like on sand hills like I have with these. Must be a higher-grade of CVTech clutches out there and like you say, these must be built for CFM. Oh well, they work OK and are close enough for my needs right now.

[Hrc630]

Yes, the oem secondary CvTech are a very basic model. Same as many clutch for artic cat atv. Some cam from artic cat are a direct fitment on our CF clutch but I don’t have try it.
 With the Trailblock primary and the oem CvTech secondary I think I have a very good set up now. Without the Trailblock I have had no succes to keeping the powerband in the sweet spot.

When I have play with the stock clutch set up I have take many notes on parts that can be use on the secondary. I will try to find it and will post the parts number so someone can try to find a better cam angle and spring.

With my set up now the backshift is excellent and the rpm is always where I want it. Just a little to low on engagement point but I don’t want to stress the drivetrain with a too high rpm engagement..

[ctdls]

  I've tunes several other clutch setup and have not has such a struggle getting the backshift right under loads like on sand hills like I have with these. Must be a higher-grade of CVTech clutches out there and like you say, these must be built for CFM.

May just be a marketing scam to say we have CV Tech clutches, like the Bose stereo in my GMC.......POS. Then the Bosch ignition module....guess where it is made